405 results on '"Vanfleteren, Jan"'
Search Results
202. Applying QMSIW technique in textile for compact wearable design and high body-antenna isolation.
- Author
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Agneessens, Sam, Lemey, Sam, Rogier, Hendrik, Vervust, Thomas, and Vanfleteren, Jan
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- 2015
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203. In situ observations on deformation behavior and stretching-induced failure of fine pitch stretchable interconnect.
- Author
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Yung-Yu Hsu, Gonzalez, Mario, Bossuyt, Frederick, Axisa, Fabrice, Vanfleteren, Jan, and De Wolf, Ingrid
- Subjects
DEFORMATIONS (Mechanics) ,ELECTRONIC equipment ,BENDING (Metalwork) ,BIOMEDICAL materials ,NUMERICAL analysis ,ELECTRONIC systems ,STRAINS & stresses (Mechanics) - Abstract
Electronic devices capable of performing in extreme mechanical conditions such as stretching, bending, or twisting will improve biomedical and wearable systems. The required capabilities cannot be achieved with conventional building geometries, because of structural rigidity and lack of mechanical stretchability. In this article, a zigzag-patterned structure representing a stretchable interconnect is presented as a promising type of building block. In situ experimental observations on the deformed interconnect are correlated with numerical analysis, providing an understanding of the deformation and failure mechanisms. The experimental results demonstrate that the zigzag-patterned interconnect enables stretchability up to 60% without rupture. This stretchability is accommodated by in-plane rotation of arms and out-of-plane deformation of crests. Numerical analysis shows that the dominating failure cause is interfacial in-plane shear stress. The plastic strain concentration at the arms close to the crests, obtained by numerical simulation, agrees well with the failure location observed in the experiment. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
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204. Conformable, Low Level Light Therapy platform
- Author
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Popp, Jürgen, Tuchin, Valery V., Matthews, Dennis L., Pavone, Francesco S., Garside, Paul, Jablonski, Michal, Bossuyt, Frederick, Vanfleteren, Jan, Vervust, Thomas, and De Smet, Herbert
- Published
- 2014
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205. Influence of barrier absorption properties on laser patterning thin organic films
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Naithani, Sanjeev, Mandamparambil, Rajesh, van Assche, Ferdie, Schaubroeck, David, Fledderus, Henri, Prenen, An, Van Steenberge, Geert, and Vanfleteren, Jan
- Abstract
This paper presents a study of selective ablation of thin organic films (LEP- Light Emitting Polymer, PEDOT:PSS- Poly 3,4-ethylenedioxythiophene: polystyrene sulfonate) by using 248 nm Excimer laser, on various kinds of multilayered SiN barrier foils for the development of Organic Light Emitting Diodes (OLED). Different Silicon Nitride (SiN) barrier foils with dedicated absorption spectra are taken into account for this purpose. The drive for looking into different types of SiN originates from the fact that the laser selective removal of a polymer without damage to the barrier layer underneath is challenging in the dynamic laser processing of thin films. The barrier is solely responsible for the proper encapsulation of the OLED stack. The main limitation of current OLED design is its shorter life span, which is directly related to the moisture or water permeation into the stack, leading to black spots. An optimization of laser parameters like fluence and number of shots has been carried out for the various types of SiN barrier foils. We are able to obtain a wider working process window for the selective removal of LEP and PEDOT:PSS from SiN barrier, by variation of the different types of SiN.
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- 2012
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206. Building flexible circuits.
- Author
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Vanfleteren, Jan
- Subjects
ELECTRICAL engineering ,ELECTRONIC circuit design - Abstract
The article discusses the ongoing technological innovations on the field of electrical engineering with primary focus on electronic circuit designs.
- Published
- 2013
207. A highly sensitive electrochemical biosensor based on AuNP-modified gold electrodes for selective determination of serum levels of crosslaps.
- Author
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Khashayar, Patricia, Amoabediny, Ghassem, Larijani, Bagher, Hosseini, Morteza, Verplancke, Rik, Keersmaecker, Michel, Adriaens, Annemie, Goemaere, Stefan, Fiers, Tom, and Vanfleteren, Jan
- Subjects
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BONE growth , *ELECTROCHEMICAL analysis , *BIOSENSORS , *GOLD electrodes , *BLOOD serum analysis - Abstract
This article explains a step-wise protocol to develop an electrochemical sensor to quantify serum levels of C-telopeptide (CTX) crosslinks also known as crosslaps in a matter of minutes and with high level of accuracy. The technique needs only one-step (incubation) and can thus be used for point of care screening. Due to the excellent electrical properties of the as-prepared immunosensor, CTX levels were successfully measured from 1 to 1000 pg/mL. This is while the normal reference of the marker is 50-450 pg/mL, suggesting that the sensor can acceptably detect CTX. The results also showed a good correlation with ECLIA in measuring serum levels of CTX. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
208. Integration of electronics in plastics using injection molding processes
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Bakr, Mona, Vanfleteren, Jan, and Bossuyt, Frederick
- Subjects
Technology and Engineering - Abstract
Door de toenemende vraag naar flexibele microsystemen, worden technologieen om die te integreren steeds belangrijker. In de laatste jaren ging veel aandacht naar de integratie in 2- en 3-dimensionele plastic onderdelen voor mogelijke toepassingen in het moderne dagelijkse leven van de mens. Bij spuitgegoten geinterconnecteerde elektronische systeem technologie worden koperbanen rechtstreeks gedeponeerd op het plastic. Dit proces heeft nood aan hoog gespecialiseerde toestellen en het proces heeft zijn beperkingen. Desalniettemin is er vraag naar kleinere en lichtere producten die gebruikmaken van verschillende materiaalcombinaties. Hiervoor werd een speciaal spuitgietproces om folies te overspuiten aangepast om elektronica te integreren in plastic onderdelen. Hierdoor werd de realisatie van zogenaamde ‘in-mould-electronics’ (IME) een feit.Dit process laat toe om elektronische componenten, apparaten en functionaliteiten te integreren in dunne spuitgegoten onderdelen, door hen in de matrijs te plaatsen en te overspuiten met een polymeer.IME is een relatief nieuwe technologie. Daarom hebben we in dit proefschrift IME geexploreerd en de toepasbaarheid van deze technologie onder verschillende spuitgiet omstandigheden onderzocht door bvb. verschillende materiaalcombinaties en verschillende types elektronische componenten te overspuiten. Daarbij moet de elektronische functionaliteit behouden blijven en een goede adhesie bekomen worden.
- Published
- 2022
209. Wearable Flexible Lightweight Modular RFID Tag With Integrated Energy Harvester.
- Author
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Lemey, Sam, Agneessens, Sam, Van Torre, Patrick, Baes, Kristof, Vanfleteren, Jan, and Rogier, Hendrik
- Subjects
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RADIO frequency identification systems , *WEARABLE technology , *INTERNET of things , *ENERGY harvesting , *WIRELESS sensor networks , *WIRELESS communications - Abstract
A novel wearable radio frequency identification (RFID) tag with sensing, processing, and decision-taking capability is presented for operation in the 2.45-GHz RFID superhigh frequency (SHF) band. The tag is powered by an integrated light harvester, with a flexible battery serving as an energy buffer. The proposed active tag features excellent wearability, very high read range, enhanced functionality, flexible interfacing with diverse low-power sensors, and extended system autonomy through an innovative holistic microwave system design paradigm that takes antenna design into consideration from the very early stages. Specifically, a dedicated textile shorted circular patch antenna with monopolar radiation pattern is designed and optimized for highly efficient and stable operation within the frequency band of operation. In this process, the textile antenna’s functionality is augmented by reusing its surface as an integration platform for light-energy-harvesting, sensing, processing, and transceiver hardware, without sacrificing antenna performance or the wearer’s comfort. The RFID tag is validated by measuring its stand-alone and on-body characteristics in free-space conditions. Moreover, measurements in a real-world scenario demonstrate an indoor read range up to 23 m in nonline-of-sight indoor propagation conditions, enabling interrogation by a reader situated in another room. In addition, the RFID platform only consumes 168.3 \mu \textW , when sensing and processing are performed every 60 s. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
210. Design and fabrication of a flexible dielectric sensor system for in situ and real-time production monitoring of glass fibre reinforced composites.
- Author
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Yang, Yang, Chiesura, Gabriele, Vervust, Thomas, Bossuyt, Frederick, Luyckx, Geert, Degrieck, Joris, and Vanfleteren, Jan
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- *
DIELECTRIC devices , *DETECTORS , *FABRICATION (Manufacturing) , *FIBROUS composites , *ELECTRODES , *FINITE element method - Abstract
Dielectric analysis has attracted great attention in recent years for the monitoring of composite production processes because of its capability to be applied in situ and in real-time. However, to progress from lab to industry level, the sensor system should be as sensitive and reliable as possible, whereas its fabrication should be simple and cost effective. In this study, a dielectric sensor system based on interdigital electrodes was developed. The system was fabricated by flexible circuit board technology, which combines low cost per unit area and high extendibility with off-the-shelf electronic components. The sensor’s geometry was optimized through analytical expressions and finite element method to maximize its sensitivity. Four-wire interconnects were simultaneously fabricated with the sensor to minimize the measurement error. A system with a signal-to-noise ratio better than 55 dB was successfully applied to monitor the production of glass fibre reinforced composites fabricated by vacuum assisted resin infusion process. The obtained data clearly shows the different key stages along the production process, proving the potential of the system. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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211. RTM Production Monitoring of the A380 Hinge Arm Droop Nose Mechanism: A Multi-Sensor Approach.
- Author
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Chiesura, Gabriele, Lamberti, Alfredo, Yang Yang, Luyckx, Geert, Van Paepegem, Wim, Vanlanduit, Steve, Vanfleteren, Jan, and Degrieck, Joris
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THERMOCOUPLES , *TRANSFER molding , *DETECTORS , *WAVELENGTHS , *TEMPERATURE - Abstract
This research presents a case study of production monitoring on an aerospace composite component: the hinge arm of the droop nose mechanism on the Airbus A380 wing leading edge. A sensor network composed of Fibre Bragg Gratings, capacitive sensors for cure monitoring and thermocouples was embedded in its fibre reinforced lay-up and measurements were acquired throughout its Resin Transfer Moulding production process. Two main challenges had to be overcome: first, the integration of the sensor lines in the existing Resin Transfer Moulding mould without modifying it; second, the demoulding of the component without damaging the sensor lines. The proposed embedding solution has proved successful. The wavelength shifts of the Fibre Bragg Gratings were observed from the initial production stages, over the resin injection, the complete curing of the resin and the cooling-down prior to demoulding. The sensors proved to be sensitive to detecting the resin flow front, vacuum and pressure increase into the mould and the temperature increase caused by the resin curing. Measurements were also acquired during the post-curing cycle. Residual strains during all steps of the process were derived from the sensors' wavelength shift, showing values up to 0.2% in compression. Moreover, the capacitive sensors were able to follow-up the curing degree during the production process. The sensors proved able to detect the resin flow front, whereas thermocouples could not measure an appreciable increase of temperature due to the fact that the resin had the same temperature as the mould. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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- View/download PDF
212. Threefold Rotationally Symmetric SIW Antenna Array for Ultra-Short-Range MIMO Communication.
- Author
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Lemey, Sam, Castel, Thijs, Torre, Patrick Van, Vervust, Thomas, Vanfleteren, Jan, Demeester, Piet, Vande Ginste, Dries, and Rogier, Hendrik
- Subjects
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SUBSTRATE integrated waveguides , *SLOT antenna arrays , *MIMO systems , *ANTENNA arrays , *INTERNET of things - Abstract
A high-performance, three-element substrate-integrated-waveguide (SIW) cavity-backed slot antenna array that covers the (5.15–5.85) GHz band is designed for integration inside or underneath the worktop of a desk, to set up a stable, high data-rate ultra-short-range $3 \times 3$ multiple-input multiple-output (MIMO) wireless communication link with a mobile user (MU) positioned on top of that worktop. The antenna topology and array geometry are carefully selected to maximally exploit the multiplexing capabilities of the ultra-short-range $3 \times 3$ MIMO channel over a wide bandwidth, yielding an increased channel capacity and/or reduced power consumption. In addition, special care was taken to guarantee a channel capacity that is less dependent on the relative orientation of the MU. Furthermore, the SIW implementation technology is combined with innovative antenna materials to guarantee a low-profile, low-cost, stable, and high-performance broadband array design that maintains its excellent performance after integration. A prototype of the antenna array was fabricated, integrated according to two different integration scenarios, and validated. Measurements prove that the antenna array allows integration into a worktop with only a minor influence on its return loss and mutual coupling, guaranteeing a bandwidth of at least 1.078 GHz and a minimum isolation between antenna elements of 30 dB within the entire (5.15–5.85) GHz band. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
213. Arbitrarily Shaped Rigid and Smart Objects Using Stretchable Interconnections.
- Author
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Chtioui, Imen, Bossuyt, Frederick, de Kok, Margreet, Vanfleteren, Jan, and Bedoui, Mohamed Hedi
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ELECTRONIC circuit design , *THERMOPLASTICS , *PRINTED circuit design , *COPPER research , *POLYETHYLENE - Abstract
In this paper, we present the developments of a new technology to realize 2.5-/3-D electronic circuits. The starting point is an electronic circuit embedded in a hard thermoplastic material, which is transformed into a 2.5-/3-D shape using a thermoforming process. The electronic circuit consists of stretchable copper interconnections in combination with electronic components. The circuit is produced using conventional printed circuit board process steps: a copper sheet is laminated on a thermoplastic material, such as Polycarbonate (PC) or Polyethylene Terephthalate Glycol (PET-G). The copper is structured using lithography and wet etching, and the electronic components are assembled using conductive adhesives. We investigated the use of different designs for stretchable interconnects to overcome the stretching of the electronic circuit by thermoforming it. A semispherical-shaped mold was used for this purpose where the local strain of the substrate can reach 100% with a sharp bending. It was shown that meander-shaped interconnects could accommodate the gradual deformation during the forming of the substrate either for PC and PET-G. However, at the mold’s edge, the copper-meandered tracks showed a delamination of the copper from the substrate. In the meanwhile, the electrical conductivity of the copper tracks did not show any significant variation. Another meander design based on an elliptical shape (in order to increase the length of the track) is proposed and compared with the first design. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
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214. Fabrication of 3-dimensional biodegradable microfluidic environments for tissue engineering applications.
- Author
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Mogosanu, Diana-Elena, Verplancke, Rik, Dubruel, Peter, and Vanfleteren, Jan
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FABRICATION (Manufacturing) , *BIODEGRADATION , *TISSUE engineering , *MICROFLUIDIC devices , *ELASTOMERS , *BIOMEDICAL materials , *EXTRACELLULAR matrix - Abstract
For future construction of implantable tissue structures, the development of 3-dimensional fluidic microsystems is necessary. In the current work we have developed a unique technology for 3-dimensional microfluidic environments with potential for tissue engineering applications. The microfluidic devices were fabricated out of biodegradable and biocompatible elastomers, such as poly (glycerol-sebacate) and poly (erythritol-sebacate), due to their transparency and thermoset properties suitable for microfabrication technologies. The three-dimensionality of the microfluidic bioreactors was imparted by a porous poly L-lactic acid membrane prepared via electrospinning. Thus obtained membrane has a high surface area-to-volume ratio and is intended to mimic the extracellular matrix that provides physical support and spatial organization. The membrane was cut and placed in between two micro-patterned microfluidic layers during the alignment process, and subsequently bonded to achieve the final bioreactor. The patency of the device network was evaluated and the bond between the microfluidic layers was sufficiently strong to allow perfusion flow rates in the range 0.1-300 μl/min. The herein developed technology comes as solution to the two-dimensionality issue that exists in most microfluidic devices and can relate to a variety of tissue engineering applications. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
215. Flexible and stretchable electronics for wearable health devices.
- Author
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van den Brand, Jeroen, de Kok, Margreet, Koetse, Marc, Cauwe, Maarten, Verplancke, Rik, Bossuyt, Frederick, Jablonski, Michael, and Vanfleteren, Jan
- Subjects
- *
ELECTRONICS , *WEARABLE antennas , *PHYSICAL measurements , *CONCRETE , *ELECTRIC properties of materials - Abstract
Measuring the quality of human health and well-being is one of the key growth areas in our society. Preferably, these measurements are done as unobtrusive as possible. These sensoric devices are then to be integrated directly on the human body as a patch or integrated into garments. This requires the devices to be very thin, flexible and sometimes even stretchable. An overview of recent technology developments in this domain and concrete application examples will be discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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216. Surface modification of an epoxy resin with polyamines and polydopamine: The effect on the initial electroless copper deposition.
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Schaubroeck, David, Mader, Lothar, De Geyter, Nathalie, Morent, Rino, Dubruel, Peter, and Vanfleteren, Jan
- Subjects
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COPPER , *EPOXY resins , *POLYAMINES , *DOPAMINE , *SURFACE chemistry , *ELECTROLESS deposition - Abstract
Highlights: [•] The surface of an epoxy resin is modified via adsorbed polyamines, polydopamine and polyamines grafted on polydopamine. [•] Introduction of polyamines leads to an increase of Pd(0) species on the surface after catalytic activation. [•] Grafted polyamines on polydopamine result in a higher initial electroless copper deposition. [Copyright &y& Elsevier]
- Published
- 2014
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217. Surface characterization and stability of an epoxy resin surface modified with polyamines grafted on polydopamine.
- Author
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Schaubroeck, David, Vercammen, Yannick, Van Vaeck, Luc, Vanderleyden, Els, Dubruel, Peter, and Vanfleteren, Jan
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SURFACE phenomenon , *CHEMICAL stability , *EPOXY resins , *POLYAMINES , *DOPAMINE , *SURFACE grafting (Polymer chemistry) - Abstract
Highlights: [•] The surface of an epoxy resin is modified with polydopamine and subsequent polyamine grafting. [•] The grafted polyamines reveal a high stability toward HCl. [•] Cluster like deposits are present on the surface after polydopamine modification. [•] XPS analysis and TOF-S-SIMS analysis of the modifications are provided. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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218. Long-term miniaturized flexible hermetic encapsulation for implantable medical devices using polymers and atomic layer deposited ceramics
- Author
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Li, Changzheng, Op de Beeck, Maaike, and Vanfleteren, Jan
- Subjects
Technology and Engineering ,Medicine and Health Sciences - Published
- 2020
219. Self-aligned flat ultra-thin chip package for flexible circuits.
- Author
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Wang, Liang, Cauwe, Maarten, Brebels, Steven, Raedt, Walter De, and Vanfleteren, Jan
- Subjects
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FLEXIBLE printed circuits , *PLASTIC embedment of electronic equipment , *SPIN coating , *DIELECTRIC films , *LITHOGRAPHY - Abstract
Purpose -- Ultra-thin chip packaging (UTCP) is one of the flexible assembly technologies, by which thinned dies are encapsulated inside spin-coated dielectric films. For sake of higher density integration and bending stress suppression, two UTCPs can be stacked vertically. The purpose of this paper is to present an improved UTCP process flow to embed thinned chip in a symmetric dielectric sandwich for a flat topography. The UTCP flat top surface is suitable for metallization and further 3D stacking. Design/methodology/approach -- In the new process, a central photosensitive polyimide film is introduced, in which a cavity is made for the embedded chip. The cavity is defined by lithography using the chip itself as a photo-mask. In this way, the cavity size and position is self-aligned to the chip. The chip thickness is compensated by the surrounding central layer, and a UTCP with flat topography (flat UTCP) is realized after top dielectric deposition. Findings -- A batch of daisy chain test vehicles was produced. The feasibility of the process flow is verified by optical and electrical measurements. The result shows 100 percent yield, which is much better than previous work. A thermal humidity test showed no significant degradation of the flat UTCPs after 1,000 hours. Originality/value -- High yield fabrication of flat UTCP is first shown. An innovative self-alignment lithography step is introduced to make a cavity in dielectric for chip thickness compensation by using the chip itself as a photo-mask. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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220. Two axis optoelectronic tactile shear stress sensor
- Author
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Missinne, Jeroen, Bosman, Erwin, Van Hoe, Bram, Verplancke, Rik, Van Steenberge, Geert, Kalathimekkad, Sandeep, Van Daele, Peter, and Vanfleteren, Jan
- Subjects
- *
OPTOELECTRONIC devices , *TACTILE sensors , *STRAINS & stresses (Mechanics) , *ROBOTICS , *MICROFABRICATION , *POLYIMIDES , *ELECTROMAGNETIC interference - Abstract
Abstract: Tactile sensors are often used on irregular or moving surfaces, for example as artificial skin on a robotic hand or inside a prosthetic socket. In addition to tactile sensors able to detect pressure, there is also a need to detect shear stress, associated with slippage or friction. Therefore, this paper demonstrates a technology for fabricating unobtrusive flexible tactile shear sensors using a thin and mechanically strong polyimide substrate. The operation of the sensor is based on the changing optical coupling between a Vertical-Cavity Surface-Emitting Laser (VCSEL) and photodiode. Since this sensor is based on an optical principle, it is less susceptible to environmental influences and electromagnetic interference (EMI). Furthermore, a new design of this sensor was developed and tested to enable the detection of both shear force magnitude and direction (two axis sensor). [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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221. The effects of encapsulation on deformation behavior and failure mechanisms of stretchable interconnects
- Author
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Hsu, Yung-Yu, Gonzalez, Mario, Bossuyt, Frederick, Axisa, Fabrice, Vanfleteren, Jan, and De Wolf, Ingrid
- Subjects
- *
DEFORMATIONS (Mechanics) , *INTEGRATED circuit interconnections , *NUMERICAL analysis , *DELAMINATION of composite materials , *COHESION , *ELECTROMECHANICAL analogies - Abstract
Abstract: In this paper, the effect of encapsulation on deformation behavior and failure mechanisms of stretchable interconnects is presented. Extensive numerical modeling is conducted for mechanical analysis of which the results are correlated with in-situ experimental observations. The numerical results reveal that by adding an encapsulation layer of various thickness (from 0.0 to 0.5mm) on top of the stretchable interconnect, the out-of-plane deformation and in-plane geometrical opening are reduced. Consequently, not only the plastic strain in the metal increases but also the in-plane shear stress at the interconnect/substrate interface. In-situ electromechanical experiments combined with scanning electron micrographs and optical images confirm the numerical analysis. More specifically, it is found that two failure mechanisms are involved during the stretching process: interfacial delamination in a S-shape alongside the metal conductor and metal breakdown at the crests of the metal conductor. The encapsulated stretchable interconnect shows both failure mechanisms at a lower percentage elongation than the non-encapsulated stretchable interconnect. Even so, the onset point of interfacial delamination for the encapsulated stretchable interconnect occurs only at an impressive number of 63% elongation and metal rupture only at 120%. The in-plane shear strain contour, obtained by numerical simulation, agrees well with the delamination failure location observed in the experiment. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
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222. Improved passive-matrix multiplexability with a modular display and UTCP technology
- Author
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Bauwens, Pieter, Monté, Ann, Christiaens, Wim, Doutreloigne, Jan, and Vanfleteren, Jan
- Subjects
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DATA transmission systems , *DIGITAL communications , *MULTIMEDIA systems , *DIGITAL video - Abstract
Abstract: One of the major problems with PM displays is that, depending on the used display material, only a limited number of lines can be multiplexed. We developed a new driving technology and display setup that takes care of that problem. We divided the display into several independent parts or modules. Each module acts as an individual display and has its own display driver. With the use of the new ultra-thin chip package (UTCP), these driver chips can be embedded into the (flexible) display itself. This paper explains the setup of the fully modular display and describes the basic structure of the display drivers and its components. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
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223. Comparison of different flex materials in high density flip chip on flex applications
- Author
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Palm, Petteri, Määttänen, Jarmo, De Maquillé, Yannick, Picault, Alain, Vanfleteren, Jan, and Vandecasteele, Björn
- Subjects
- *
GLASS , *DENSITY - Abstract
This paper presents the results from the evaluation of different types of flexible substrates for high-density flip chip application. In this work four different flexible substrates were used. The flex substrates were Espanex, Upilex and epoxy glass with 80 μm pitch and Upilex with 54 μm pitch. Two different test IC’s were used for both pitches. In test IC1 (80 μm pitch) and IC3 (54 μm pitch) the bumps were in one row and test IC2 (80 μm pitch) and IC4 (54 μm pitch) in two rows. The total amount of contacts in test IC1 was 190, in test IC2 173, in test IC3 293 and in test IC4 270. The anisotropically conductive adhesive that was used in the tests was epoxy based thermosetting adhesive film with conductive particles. The conductive particles in the adhesives were isolated soft metal-coated polymer particles. The contact resistance was measured using Kelvin four-point method and the continuity and series resistance using daisy chain structure. The reliability of the flip chip interconnections was tested in temperature cycling test and environmental test. Cross section samples were made to analyse the possible reason for failures. The results presented in this paper are from FLEXIL development project that is part of European Union IST research program. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
224. Low-profile antenna systems for the Next-Generation Internet of Things applications
- Author
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Lemey, Sam, Rogier, Hendrik, and Vanfleteren, Jan
- Subjects
Technology and Engineering ,IBCN - Published
- 2016
225. Design, technology and evaluation of a microfluidic chip for point-of-care diagnosis of bone turnover biomarkers
- Author
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Khashayar, Patricia, Vanfleteren, Jan, Amoabediny, Ghasem, Larijani, Bagher, and Verplancke, Rik
- Subjects
Technology and Engineering ,Medicine and Health Sciences - Published
- 2016
226. Biodegradable fluidic microsystems for cell cultures and tissue engineering
- Author
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Mogosanu, Diana-Elena, Vanfleteren, Jan, and Dubruel, Peter
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Biology and Life Sciences - Published
- 2016
227. Surface modifications of epoxy resins to improve the adhesion towards electroless deposited copper
- Author
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David Schaubroeck, Vanfleteren, Jan, and Dubruel, Peter
- Subjects
adhesion ,Technology and Engineering ,Surface modification ,electroless copper ,polydopamine ,epoxy resin - Published
- 2015
228. Transfer of the electroless nickel metallization process into microsystem technology
- Author
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Ostmann, Andreas, Lang, Klaus-Dieter, Technische Universität Berlin, Fakultät IV - Elektrotechnik und Informatik, Vanfleteren, Jan, and Nowottnick, Mathias
- Subjects
ddc:620 - Abstract
Eines der wichtigsten Verfahren der Aufbau- und Verbindungstechnik (AVT) ist die Flip-Chip-Technik. Die beim Flip-Chip-Verbinden durch Löten oder Kleben erzeugten elektrischen Kontakte erfordern die zusätzliche Erzeugung von Bumps auf den Anschlußflächen der Halbleiter. Der stetige Kostendruck in der Elektronikindustrie verlangt auch eine Reduzierung der Kosten für das Bumping von Halbleiterwafern. Ein potentiell sehr kostengünstiges Bumpingverfahren bietet die selektive chemische Metallabscheidung auf Al-Kontaktpads mittels chemischer Metallisierung. Im Rahmen dieser Arbeit wurden umfassende Untersuchungen zur chemischen Metallabscheidung auf Halbleiterwafern durchgeführt. Es konnte gezeigt werden, daß sich auf Al-Kontaktflächen durch eine alkalische Reinigung, gefolgt von einer Doppelzinkat-Behandlung, feinkörnige Zn-Schichten abscheiden lassen, welche zu hoher Bumphaftung führen. Der Einfluß des Stabilisators in Ni-Bädern auf die Ni-Abscheidung wurde untersucht. Für den Zusammenhang zwischen kritischer Stabilisatorkonzentration und Padgröße wurde ein Modell aufgestellt und experimentell verifiziert. Die bei der chemischen Metallisierung funktioneller Halbleiterwafer auftretenden Effekte wurden untersucht. Es ließ sich zeigen, mit welchen Maßnahmen diese Effekte beeinflußt bzw. vermieden werden können. Es konnte eine Prozeßkette zum chemischen Bumping entwickelt werden, deren wesentlicher Bestandteil ein Meßverfahren für den Stabilisatorgehalt ist. Gemäß den Anforderungen der Behandlungsschritte wurde eine Anlage entworfen und aufgebaut. Die Tauglichkeit des Prozesses ließ sich anhand von verschiedenen Wafertypen unterschiedlicher Technologien erfolgreich verifizieren und die Gleichmäßigkeit und Zuverlässigkeit der abgeschiedenen Ni-Bumps nachweisen. Für verschiedene Produktionsszenarien des chemischen Bumpings wurde ein Kostenmodell erstellt. Es ließ sich zeigen, daß ein Waferbumping mit Kosten bis herunter zu 2,10 € pro Wafer möglich ist. Abschließend wurden Untersuchungen zur Zuverlässigkeit von Ni-Bumps in Flip-Chip-Verbindungen durchgeführt. Bei Chips mit Ni-Bumps, welche mittels Flip-Chip-Klebe-Technik montiert wurden, war stets der verwendete Klebstoff der limitierende Faktor bei den Zuverlässigkeitstests. Auch beim Flip-Chip-Löten mit chemisch abgeschiedenen Ni-Unter-Bump-Metallisierungen konnte für verschiedene Lottypen eine sehr gute Beständigkeit bei thermischen und thermomechanischen Belastungstests nachgewiesen werden. Flip chip technology is an important process in microelectronics packaging. Flip chip interconnections by solder or adhesive require the processing of bumps on semiconductor contact pads. The requirement for cost reduction leads to the demand for reduced bumping cost. The selective chemical metallization of semiconductor wafers offers a potential low-cost alternative to established technologies. In this thesis a comprehensive investigation of chemical metal deposition on wafers was performed. It was demonstrated that an alkaline cleaning, followed by a double-zincate treatment can result in a fine-grained Zn layer, which provides strong bump adhesion. The influence of stabilizer in Ni bathes was studied. For the relation between critical stabilizer concentration and pad size a model was developed and experimentally verified. Effects of chemical metallization of functional wafers were investigated and countermeasures were found. A productive process for chemical bumping was developed, including a method for precise measurement of stabilizer concentration. According process requirements a bumping line was designed and realized. The capability of the process as well as uniformity and reliability of Ni bumps were demonstrated by successful bumping of different types of wafers. Taking into account different production scenarios a cost model of chemical bumping was set up. It could be shown that bumping at cost as low as 2.10 € per wafer is possible. Finally the reliability of flip chips with Ni bumps was investigated. In stress tests using glued flip chips the reliability was limited by the adhesive materials only. Also for flip chip interconnects using Ni Under Bump Metallization and different types of solder an excellent stability in thermal and thermo-mechanical stress tests was demonstrated.
- Published
- 2014
229. Conformable light emitting modules
- Author
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Jablonski, Michal, Vanfleteren, Jan, and Bossuyt, Frederick
- Subjects
Technology and Engineering - Abstract
As we become increasingly aware that there is more to light than the image it forms on our retina, and as we become more environmentally aware, the value of non-image-forming light increases along with the need for various new light related appliances. In particular, some lighting related applications are emerging which demand conformability (flexibility and stretchability). Well-being, automotive or wearable electronic applications are just a few examples where these trends can be observed. We are finding that conformability could bring various benefits to both users (tactile and optical comfort, optical efficiency, multi-functionality, work/living space savings) as well as manufacturers (heterogeneous integration, light-weight, design freedom, differentiation and less stringent tolerancing). Developed by Ghent University, the SMI (Stretchable Molded Interconnect) technology attempts to address these demands and has been the main focus of this work. With the SMI technology it was possible to design highly conformable circuits using fabrication methods similar to these found in the PCB and FCB industries and standard off-the-shelf electronic components. The goal of this work was to characterize the technology materials in terms of mechanical, optical and reliability performance as well as define a set of design rules to support creation of robust and efficient light modules, also using a set of new, commercially available elastomeric, polymer materials. The developments are illustrated with demonstration devices.
- Published
- 2014
230. Generic technology platform for the integration of microelectronics and microfluidics on stretchable substrates
- Author
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Rik Verplancke, Vanfleteren, Jan, and Cuypers, Dieter
- Subjects
Technology and Engineering - Published
- 2013
231. Design and Technology of Ultra Thin Chip Packages for High-Frequency Applications up to 60 GHz
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Wang, Liang, Vanfleteren, Jan, De Raedt, Walter, and Cauwe, Maarten
- Subjects
Technology and Engineering - Published
- 2013
232. 3D-stacking of ultra-thin chips and chip packages
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Priyabadini, Swarnakamal, Vanfleteren, Jan, and Sterken, Tom
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Technology and Engineering - Published
- 2013
233. Development of a stretchable platform for the fabrication of biocompatible microsystems
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Jahanshahi, Amir and Vanfleteren, Jan
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Technology and Engineering - Published
- 2013
234. Stretchable and washable electronics for embedding in textiles
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Vervust, Thomas and Vanfleteren, Jan
- Subjects
Technology and Engineering - Published
- 2012
235. Design and implementation of a mobile sensor system for human posture tracking
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Huyghe, Benoît, Doutreloigne, Jan, and Vanfleteren, Jan
- Subjects
Wireless Ad Hoc Network ,Sensor Nodes ,Technology and Engineering ,Posture Tracking ,Kalman Filter - Abstract
De reconstructie van menselijke houding en het traceren van bewegingen kan in vele toepassingen worden gebruikt. Van animatie waar de bewegingen van acteurs kunnen gekoppeld worden aan een digitaal personage, tot revalidatie waar artsen na biomechanische analyse snel accurate diagnoses kunnen stellen. De snelle evolutie in de ontwikkeling van microsensoren en de opkomst van draadloze sensornetwerken hebben ertoe geleid dat draadloze nodes met verschillende sensoren hiervoor kunnen worden gebruikt. Door de informatie van deze sensoren te combineren is het immers mogelijk om absolute oriëntatie te berekenen. Eens deze informatie van elk lichaamsdeel bekend is, kan de volledige houding gereconstrueerd worden. In dit onderzoek werd een inertieel traceringssysteem ontwikkeld waarbij, in tegenstelling tot commerciële oplossingen, geen gyroscopen werden gebruikt. De sensor nodes worden enkel voorzien van accelerometers en magnetometers. Computer software implementeert het traceringssalgoritme en visualiseert de gereconstrueerde menselijke houding. Ingebedde software bepaalt dan weer de werking van de nodes en implementeert een draadloos protocol op maat dat toelaat om de informatie van verschillende nodes te ontvangen. De werking van het volledige systeem werd gevalideerd aan de hand van experimenten waarbij de houding van een persoon werd gevolgd. Human posture reconstruction and motion tracking is of interest for many different applications. From animation where captured motion sequences from actors can be mapped to a digital character in order to obtain a realistic visualization, to revalidation, where biomechanical analysis enables physicians to determine which exercises should be executed for a better and faster recovery. The combination of the increasingly fast evolution in the development of micromachined and the rise of wireless sensor networks as a distributed solution has allowed inertial sensors to become a fast emerging technology for orientation tracking. Sensor nodes equipped with accelerometers, magnetometers and gyroscopes supply three dimensional readings that can be used to determine driftfree absolute orientation. By approximating the human body by a set of rigid structures interconnected by joints, posture reconstruction is made possible when each of the individual bodyparts is equipped with a sensor node. In this work, an inertial tracking system was developed where, contrast to commercial applications, no gyroscopes were included. The sensor nodes were only equipped with accelerometers and magnetometers. Computer software implements the tracking algorithm and visualizes the reconstructed human posture. Embedded software determines the functionality of the nodes and implements a fully custom wireless protocol that allows to receive information from several nodes. The functionality of the entire system was validated by conducting full body tracking experiments.
- Published
- 2011
236. PoCOsteo: generic novel platform for bone turnover marker measurement & monitoring.
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Khashayar P, Lopes P, Ragaert P, Hoogenboom R, Latta D, Gransee R, Lenartowicz D, Biggs P, Etxebarria I, Luegger B, Obermayer-Pietsch B, Dimai HP, and Vanfleteren J
- Subjects
- Humans, Immunoassay methods, Peptides blood, Biosensing Techniques methods, Point-of-Care Systems, Biomarkers blood, Biomarkers analysis, Procollagen blood, Collagen Type I blood, Bone Remodeling physiology, Peptide Fragments blood
- Abstract
Despite the increasing efforts in improving bone health assessments, current diagnostics suffer from critical shortcomings. The present article therefore describes a multiplex label-free immunosensor designed and validated for the assessment of two bone turnover markers (BTMs), namely beta isomerized C-terminal telopeptide of type I collagen (CTx) and Procollagen I Intact N-Terminal (PINP), the combination of which is needed to illustrate an accurate overview of bone health. The immunosensor was then tested outside and inside of a microsystem, with the aim of becoming compatible with a point of care system fabricated for automated assessment of these biomarkers later-on at patient side. Custom-made monoclonal antibodies were specifically designed for this purpose in order to guarantee the selectivity of the immunosensor. In the final platform, a finger prick blood sample is introduced into the microfluidic manifolds without any need for sample preparation step, making the tool suitable for near patient and outside of the central laboratory applications. The platform was exploited in 30 real blood samples with the results validated using electrochemiluminescence immunoassay. The results revealed the platform was capable of measuring the target analyte with high sensitivity and beyond the recommended clinical reference range for each biomarker (CTx: 104-1028 ng L
-1 and PINP: 16-96 μg L-1 , correspondingly). They also showed the platform to have a limit of detection of 15 (ng L-1 ) and 0.66 (μg L-1 ), a limit of quantification of 49 (ng L-1 ) and 2.21 (μg L-1 ), and an inter- and intra-assay coefficient of variance of 5.39-6.97% and 6.81-5.37%, for CTx and PINP respectively, which is comparable with the gold standard. The main advantage of the platform over the state-of-the art was the capability of providing the results for two markers recommended for assessing bone health within 15 minutes and without the need for skilled personnel or costly infrastructure.- Published
- 2024
- Full Text
- View/download PDF
237. Multifunctional Poly(2-ethyl-2-oxazoline) Copolymers Containing Dithiolane and Pentafluorophenyl Esters as Effective Reactive Linkers for Gold Surface Coatings.
- Author
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Sedlacek O, Egghe T, Khashayar P, Purino M, Lopes P, Vanfleteren J, De Geyter N, and Hoogenboom R
- Subjects
- Polyamines chemistry, Esters chemistry, Polymers chemistry
- Abstract
Surface functionalization with biological macromolecules is an important task for the development of sensor materials, whereby the interaction with other biological materials should be suppressed. In this work, we developed a novel multifunctional poly(2-ethyl-2-oxazoline)-dithiolane conjugate as a versatile linker for gold surface immobilization of amine-containing biomolecules, containing poly(2-ethyl-2-oxazoline) as antifouling polymer, dithiolane for surface immobilization, and activated esters for protein conjugation. First, a well-defined carboxylic acid containing copoly(2-ethyl-2-oxazoline) was synthesized by cationic ring-opening copolymerization of 2-ethyl-2-oxazoline with a methyl ester-containing 2-oxazoline monomer, followed by postpolymerization modifications. The side-chain carboxylic groups were then converted to amine-reactive pentafluorophenyl (PFP) ester groups. Part of the PFP groups was used for the attachment of the dithiolane moiety, which can efficiently bind to gold surfaces. The final copolymer contained 1.4 mol% of dithiolane groups and 4.5 mol% of PFP groups. The copolymer structure was confirmed by several analytical techniques, including NMR spectroscopy and size-exclusion chromatography. The kinetics of the PFP ester aminolysis and hydrolysis demonstrated significantly faster amidation compared to hydrolysis, which is essential for subsequent protein conjugation. Successful coating of gold surfaces with the polymer was confirmed by spectroscopic ellipsometry, showing a polymer brush thickness of 4.77 nm. Subsequent modification of the coated surfaces was achieved using bovine serum albumin as a model protein. This study introduces a novel reactive polymer linker for gold surface functionalization and offers a versatile polymer platform for various applications including biosensing and surface functionalization.
- Published
- 2023
- Full Text
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238. Methods to Improve Accuracy of Electronic Component Positioning in Thermoformed Electronics.
- Author
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Madadnia B, Vanfleteren J, and Bossuyt F
- Abstract
Three new methods for accurate electronic component positioning for thermoformed electronics are presented in this paper. To maintain the mechanical and electrical properties of printed-ink tracks, prevent deformation and stretching during thermoforming, and ensure reproducibility, the component positioning principle for all three proposed methods is based on keeping the temperature of some regions in the thermoplastic substrate less than the glass transition temperature of the thermoplastic carrier, to keep those regions resistant to plastic deformation. We have verified the accuracy of the different approaches by implementing these methods in a semi-sphere mold for positioning seven LEDs and one printed capacitive touch sensor. We compared the result of our fabrication processes with the typical fabrication process of in-mold electronics (direct printing on a thermoplastic foil and followed by a thermoforming step) and noticed that the sample produced by the typical process had tracks that were randomly stretched, tracks were not in a straight path after thermoforming and they were not electrically conductive. Furthermore, the final 3D position of the components was not reproducible sample by sample. However, with our proposed fabrication methods, the tracks and pads do not deform or expand during thermoforming and are electrically conductive after. Moreover, the round shape of the touch sensor remains the same as in the 2D design. Based on the results of the experiments, it appears that the proposed methods are capable of positioning electronic components with high precision in thermoformed electronics.
- Published
- 2023
- Full Text
- View/download PDF
239. Parameter Study on Force Curves of Assembled Electronic Components on Foils during Injection Overmolding Using Simulation.
- Author
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Hubmann M, Bakr M, Groten J, Pletz M, Vanfleteren J, Bossuyt F, Madadnia B, and Stadlober B
- Abstract
The integration of assembled foils in injection-molded parts is a challenging step. Such assembled foils typically comprise a plastic foil on which a circuit board is printed and electronic components are mounted. Those components can detach during overmolding when high pressures and shear stresses prevail due to the injected viscous thermoplastic melt. Hence, the molding settings significantly impact such parts' successful, damage-free manufacturing. In this paper, a virtual parameter study was performed using injection molding software in which 1206-sized components were overmolded in a plate mold using polycarbonate (PC). In addition, experimental injection molding tests of that design and shear and peel tests were made. The simulated forces increased with decreasing mold thickness and melt temperature and increasing injection speed. The calculated tangential forces in the initial stage of overmolding ranged from 1.3 N to 7.3 N, depending on the setting used. However, the experimental at room temperature-obtained shear forces at break were at least 22 N. Yet, detached components were present in most of the experimentally overmolded foils. Hence, the shear tests performed at room temperature can only provide limited information. In addition, there might be a peel-like load case during overmolding where the flexible foil might bend during overmolding.
- Published
- 2023
- Full Text
- View/download PDF
240. Measuring the Flex Life of Conductive Yarns in Narrow Fabric.
- Author
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Veske P, Bossuyt F, Thielemans F, and Vanfleteren J
- Abstract
Due to constant advancements in materials research, conductive textile-based materials have been used increasingly in textile-based wearables. However, due to the rigidity of electronics or the need for their encapsulation, conductive textile materials, such as conductive yarns, tend to break faster around transition areas than other parts of e-textile systems. Thus, the current work aims to find the limits of two conductive yarns woven into a narrow fabric at the electronics encapsulation transition point. The tests consisted of repeated bending and mechanical stress, and were conducted using a testing machine built from off-the-shelf components. The electronics were encapsulated with an injection-moulded potting compound. In addition to identifying the most reliable conductive yarn and soft-rigid transition materials, the results examined the failure process during the bending tests, including continuous electrical measurements.
- Published
- 2023
- Full Text
- View/download PDF
241. Development of a Microfluidic Chip Powered by EWOD for In Vitro Manipulation of Bovine Embryos.
- Author
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Karcz A, Van Soom A, Smits K, Van Vlierberghe S, Verplancke R, Pascottini OB, Van den Abbeel E, and Vanfleteren J
- Subjects
- Animals, Cattle, Humans, Mice, Electrowetting methods, Oligonucleotide Array Sequence Analysis, Microfluidics methods, Microfluidic Analytical Techniques
- Abstract
Digital microfluidics (DMF) holds great potential for the alleviation of laboratory procedures in assisted reproductive technologies (ARTs). The electrowetting on dielectric (EWOD) technology provides dynamic culture conditions in vitro that may better mimic the natural embryo microenvironment. Thus far, EWOD microdevices have been proposed for in vitro gamete and embryo handling in mice and for analyzing the human embryo secretome. This article presents the development of the first microfluidic chip utilizing EWOD technology designed for the manipulation of bovine embryos in vitro. The prototype sustains the cell cycles of embryos manipulated individually on the chips during in vitro culture (IVC). Challenges related to the chip fabrication as well as to its application during bovine embryo IVC in accordance with the adapted on-chip protocol are thoroughly discussed, and future directions for DMF in ARTs are indicated.
- Published
- 2023
- Full Text
- View/download PDF
242. Process Optimization of Injection Overmolding Structural Electronics with Regard to Film Distortion.
- Author
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Hubmann M, Madadnia B, Groten J, Pletz M, Vanfleteren J, Stadlober B, Bossuyt F, Kaur J, and Lucyshyn T
- Abstract
The integration of structural electronics in injection-molded parts is a challenging step. The films-comprising of laminated stacks with electronics-are exposed to shear stresses and elevated temperatures by the molten thermoplastic. Hence, molding settings have a significant impact on the successful, damage-free manufacturing of such parts. In this paper, test films with polycarbonate (PC) sheets as outer and two different thermoplastic polyurethanes (TPUs) as middle layers incorporating conductive tracks on a flexible printed circuit board (flexPCB) are manufactured and overmolded with PC. Parameter studies investigating the influence of the melt temperature, mold temperature, injection speed and used TPU layer were performed. The molded parts were inspected visually and compared with a numerical simulation using injection molding software. A shear distortion factor for the TPU layer was derived based on the simulations that linked the shear stresses with the injection time and the softening (melting) of the TPU. The distortion of the films was found to reduce with higher melt temperature, lower mold temperature and faster injection speed. Films using the TPU with the higher melting temperature yielded significantly better results. Moreover, distortion on the films reduced with the increasing distance to the gate and a larger cavity thickness was found to be beneficial. All those relations could be correlated with the shear distortion factor.
- Published
- 2022
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243. A Study on Over-Molded Copper-Based Flexible Electronic Circuits.
- Author
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Bakr M, Hubmann M, Bossuyt F, and Vanfleteren J
- Abstract
Over-molding has been proposed in recent years as an integrated functional flexible circuit board in a plastic part. This method uses the conventional process for film insert technology. Over-molding has attracted significant attention across many industries due to its potential to deliver different electrical functions in a variety of different part geometries, especially in automotive interiors and home appliances. While it has great application potential, manufacturing challenges continue throughout foil fabrication and injection molding. This raises challenges for designers and researchers responsible for maintaining the reliability of such electronic flexible circuits. Therefore, the purpose of this research paper is to improve some of the over-molding process parameters. On 0805 and 1206 over-molded zero-ohm resistors, electrical, mechanical, and failure characterization was performed. Those components were mounted in parallel, perpendicular, and 45° angled arrangements on two different polymer substrates, polyimide (PI) and polyethylene terephthalate (PET) using lead-free solder, low-melt solder, and conductive adhesive paste. Moreover, as an over-molding material, polycarbonate (PC) with medium viscosity was used. The effect of using different mold shapes (corner mold, 2 mm flat mold, and 3 mm flat mold) and injection molding process parameters (injection speeds and melt temperature) was studied.
- Published
- 2022
- Full Text
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244. Electrically-driven handling of gametes and embryos: taking a step towards the future of ARTs.
- Author
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Karcz A, Van Soom A, Smits K, Verplancke R, Van Vlierberghe S, and Vanfleteren J
- Subjects
- Animals, Culture Media, Embryo, Mammalian physiology, Germ Cells, Mammals, Electrowetting, Reproductive Techniques, Assisted
- Abstract
Electrical stimulation of gametes and embryos and on-chip manipulation of microdroplets of culture medium serve as promising tools for assisted reproductive technologies (ARTs). Thus far, dielectrophoresis (DEP), electrorotation (ER) and electrowetting on dielectric (EWOD) proved compatible with most laboratory procedures offered by ARTs. Positioning, entrapment and selection of reproductive cells can be achieved with DEP and ER, while EWOD provides the dynamic microenvironment of a developing embryo to better mimic the functions of the oviduct. Furthermore, these techniques are applicable for the assessment of the developmental competence of a mammalian embryo in vitro . Such research paves the way towards the amelioration and full automation of the assisted reproduction methods. This article aims to provide a summary on the recent developments regarding electrically stimulated lab-on-chip devices and their application for the manipulation of gametes and embryos in vitro .
- Published
- 2022
- Full Text
- View/download PDF
245. Testing for Wearability and Reliability of TPU Lamination Method in E-Textiles.
- Author
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Veske P, Bossuyt F, and Vanfleteren J
- Subjects
- Electronics, Reproducibility of Results, Textiles, Polyurethanes, Wearable Electronic Devices
- Abstract
Electronic textiles (e-textiles) and wearable computing have been emerging increasingly during the last decade. Since the market interest and predictions have grown, the research into increasing reliability and durability of wearables and e-textiles is developing rapidly. The washability of different integration methods and resistance to mechanical stress are the main obstacles being tackled. However, the freedom of movement and overall comfort is still often overlooked during the development phase. It is essential to see the e-textile product as a whole and consider several aspects of user experience. This work will focus on developing and improving the thermoplastic polyurethane (TPU) lamination integration method for e-textiles. In the work, a stretchable copper-polyimide based circuit was laminated onto knit fabric using various TPU films and stacks. The study shares measurable characteristics to determine which material assembly and design would ensure the highest durability for the electronics part without losing its original textile softness, flexibility and stretchability.
- Published
- 2021
- Full Text
- View/download PDF
246. In vivo blue light illumination for optogenetic inhibition: effect on local temperature and excitability of the rat hippocampus.
- Author
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Acharya AR, Vandekerckhove B, Larsen LE, Delbeke J, Wadman WJ, Vonck K, Carette E, Meurs A, Vanfleteren J, Boon P, Missinne J, and Raedt R
- Subjects
- Animals, Rats, Time Factors, Hippocampus physiology, Lighting, Opsins metabolism, Optogenetics methods, Photic Stimulation, Temperature
- Abstract
Objective. The blue light-activated inhibitory opsin, stGtACR2, is gaining prominence as a neuromodulatory tool due its ability to shunt-inhibit neurons and is being frequently used in in vivo experimentation. However, experiments involving stGtACR2 use longer durations of blue light pulses, which inadvertently heat up the local brain tissue and confound experimental results. Therefore, the heating effects of illumination parameters used for in vivo optogenetic inhibition must be evaluated. Approach. To assess blue light (473 nm)-induced heating of the brain, we used a computational model as well as direct temperature measurements using a fiber Bragg grating (FBG). The effects of different light power densities (LPDs) and pulse durations on evoked potentials (EP) recorded from dentate gyrus were assessed. For opsin-negative rats, LPDs between 127 and 636 mW mm
-2 and pulse durations between 20 and 5120 ms were tested while for stGtACR2 expressing rats, LPD of 127 mW mm-2 and pulse durations between 20 and 640 ms were tested. Main results. Increasing LPDs and pulse durations logarithmically increased the peak temperature and significantly decreased the population spike (PS) amplitude and latencies of EPs. For a pulse duration of 5120 ms, the tissue temperature increased by 0.6 °C-3.4 °C. All tested LPDs decreased the PS amplitude in opsin-negative rats, but 127 mW mm-2 had comparatively minimal effects and a significant effect of increasing light pulse duration was seen from 320 ms and beyond. This corresponded with an average temperature increase of 0.2 °C-1.1 °C at the recorded site. Compared to opsin-negative rats, illumination in stGtACR2-expressing rats resulted in much greater inhibition of EPs. Significance. Our study demonstrates that light-induced heating of the brain can be accurately measured in vivo using FBG sensors. Such light-induced heating alone can affect neuronal excitability. Useful neuromodulation by the activation of stGtACR2 is still possible while minimizing thermal effects., (© 2021 IOP Publishing Ltd.)- Published
- 2021
- Full Text
- View/download PDF
247. Ex Vivo Generation and Characterization of Human Hyaline and Elastic Cartilaginous Microtissues for Tissue Engineering Applications.
- Author
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Sánchez-Porras D, Durand-Herrera D, Paes AB, Chato-Astrain J, Verplancke R, Vanfleteren J, Sánchez-López JD, García-García ÓD, Campos F, and Carriel V
- Abstract
Considering the high prevalence of cartilage-associated pathologies, low self-repair capacity and limitations of current repair techniques, tissue engineering (TE) strategies have emerged as a promising alternative in this field. Three-dimensional culture techniques have gained attention in recent years, showing their ability to provide the most biomimetic environment for the cells under culture conditions, enabling the cells to fabricate natural, 3D functional microtissues (MTs). In this sense, the aim of this study was to generate, characterize and compare scaffold-free human hyaline and elastic cartilage-derived MTs (HC-MTs and EC-MTs, respectively) under expansion (EM) and chondrogenic media (CM). MTs were generated by using agarose microchips and evaluated ex vivo for 28 days. The MTs generated were subjected to morphometric assessment and cell viability, metabolic activity and histological analyses. Results suggest that the use of CM improves the biomimicry of the MTs obtained in terms of morphology, viability and extracellular matrix (ECM) synthesis with respect to the use of EM. Moreover, the overall results indicate a faster and more sensitive response of the EC-derived cells to the use of CM as compared to HC chondrocytes. Finally, future preclinical in vivo studies are still needed to determine the potential clinical usefulness of these novel advanced therapy products.
- Published
- 2021
- Full Text
- View/download PDF
248. Technological Challenges in the Development of Optogenetic Closed-Loop Therapy Approaches in Epilepsy and Related Network Disorders of the Brain.
- Author
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Vandekerckhove B, Missinne J, Vonck K, Bauwens P, Verplancke R, Boon P, Raedt R, and Vanfleteren J
- Abstract
Epilepsy is a chronic, neurological disorder affecting millions of people every year. The current available pharmacological and surgical treatments are lacking in overall efficacy and cause side-effects like cognitive impairment, depression, tremor, abnormal liver and kidney function. In recent years, the application of optogenetic implants have shown promise to target aberrant neuronal circuits in epilepsy with the advantage of both high spatial and temporal resolution and high cell-specificity, a feature that could tackle both the efficacy and side-effect problems in epilepsy treatment. Optrodes consist of electrodes to record local field potentials and an optical component to modulate neurons via activation of opsin expressed by these neurons. The goal of optogenetics in epilepsy is to interrupt seizure activity in its earliest state, providing a so-called closed-loop therapeutic intervention. The chronic implantation in vivo poses specific demands for the engineering of therapeutic optrodes. Enzymatic degradation and glial encapsulation of implants may compromise long-term recording and sufficient illumination of the opsin-expressing neural tissue. Engineering efforts for optimal optrode design have to be directed towards limitation of the foreign body reaction by reducing the implant's elastic modulus and overall size, while still providing stable long-term recording and large-area illumination, and guaranteeing successful intracerebral implantation. This paper presents an overview of the challenges and recent advances in the field of electrode design, neural-tissue illumination, and neural-probe implantation, with the goal of identifying a suitable candidate to be incorporated in a therapeutic approach for long-term treatment of epilepsy patients.
- Published
- 2020
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249. Numerical simulation of a multi-inlet microfluidic device for biosensing purposes in osteoporosis management.
- Author
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Khashayar P, Okhovat A, Adibi H, Windels J, Amoabediny G, Larijani B, and Vanfleteren J
- Abstract
Objectives: In this paper, the effect of the position of the inlet and outlet microchannels on the flow profile and the geometry of the recognition chamber for sample pre-treatment in an electrochemical biosensor to be used in osteoporosis management were investigated., Methods: All numerical computation presented in this work were performed using COMSOL Multiphysics and Fluent. Simulation was performed for a three-dimensional, incompressible Navier-Stokes flow and so explicit biphasic volume of fluid (VOF) equations were used., Results: In the designed microfluidic system, a pressure-driven laminar flow with no-slip boundary condition was responsible for fluid actuation through microchannels in a reproducible approach. Based on the simulation results, the number of outlets was increased and the angel through which the inlets and outlets were attached to the microchamber was changed so that the dead volume would be eliminated and the fluid flow trajectory, the velocity field and pressure were evenly distributed across the chamber. The Re number in the inlets was equal to 4.41, suggesting a laminar flow at this site., Conclusion: The simulation results along with the fact that the design change was tested using laser ablated tape and a color dye at different steps provided the researchers with the opportunity to study the changes in a fast and accurate but cheap method. The absence of backflow helps with the cross-talk concern in the channels and the lack of bubbles and complete coverage of the chamber helps with a better surface modification and thus better sensing performance., Competing Interests: Conflict of interestThe authors declared that they have no conflict of interest., (© Springer Nature Switzerland AG 2019.)
- Published
- 2019
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250. Design and Integration of Flexible Sensor Matrix for in Situ Monitoring of Polymer Composites.
- Author
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Yang Y, Chiesura G, Plovie B, Vervust T, Luyckx G, Degrieck J, Sekitani T, and Vanfleteren J
- Subjects
- Pliability, Temperature, Vacuum, Vitrification, Electronics instrumentation, Epoxy Resins chemistry, Equipment Design
- Abstract
Sensory polymer composites are highly desirable for applications such as in situ and real-time production processes and structural health monitoring, and for technologies that include human-machine interfaces for the next generation of Internet of Things. However, the development of these materials is still in its infancy: these materials have been reported, but the large-scale fabrication of polymer composites with versatile and customizable sensing capabilities has yet to be demonstrated. Here, we report on a scalable fabrication strategy that enables such materials by designing and integrating PCB technology-inspired large-area flexible sensor matrices into polymer composites. The integrated sensor matrices successfully monitored in situ the production processes and structural health of an industrial polymer composite: from the application of vacuum, resin flow and polymerization, production defects, and temperature distribution. Our results demonstrate that the proposed strategy is a simple and effective solution as a distributed monitoring platform for polymer composites and shows the potential toward next generation of sensory polymer composites.
- Published
- 2018
- Full Text
- View/download PDF
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