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While aerial shark spotting has been a standard practice for beach safety for decades, new technologies offer enhanced opportunities, ranging from drones/unmanned aerial vehicles (UAVs) that provide new viewing capabilities, to new apps that provide beachgoers with up-to-date risk analysis before entering the water. This report describes the Sharkeye platform, a first-of-its-kind project to demonstrate personal shark alerting for beachgoers in the water and on land, leveraging innovative UAV image collection, cloud-hosted machine learning detection algorithms, and reporting via smart wearables. To execute, our team developed a novel detection algorithm trained via machine learning based on aerial footage of real sharks and rays collected at local beaches, hosted and deployed the algorithm in the cloud, and integrated push alerts to beachgoers in the water via a shark app to run on smartwatches. The project was successfully trialed in the field in Kiama, Australia, with over 350 detection events recorded, followed by the alerting of multiple smartwatches simultaneously both on land and in the water, and with analysis capable of detecting shark analogues, rays, and surfers in average beach conditions, and all based on ~1 h of training data in total. Additional demonstrations showed potential of the system to enable lifeguard-swimmer communication, and the ability to create a network on demand to enable the platform. Our system was developed to provide swimmers and surfers with immediate information via smart apps, empowering lifeguards/lifesavers and beachgoers to prevent unwanted encounters with wildlife before it happens.

Alginate has been a biologically viable option for controlled local delivery of bioactive molecules in vitro and in vivo. Specific bioactive molecule release profiles are achieved often by controlling polymer composition/concentration, which also determines the modulus of hydrogels. This largely limits alginate-mediated bioactive molecule delivery to single-factors of uniform concentration applications, rather than applications that may require (multiple) bioactive molecules delivered at a concentration gradient for chemotactic purposes. Here we report a two-phase PLGA/alginate delivery system composed of protein-laden poly-d,l-lactic-co-glycolic acid (PLGA) microspheres wet-spun into alginate fibres. Fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) was used as a model protein and the developed structures were characterized. The fabrication system devised was shown to produce wet-spun fibres with a protein concentration gradient (G-Alg/PLGA fibre). The two-phase delivery matrices display retarded FITC-BSA release in both initial and late stages compared to release from the PLGA microspheres or alginate fibre alone. In addition, incorporation of higher concentrations of protein-loaded PLGA microspheres increased protein release compared to the fibres with lower concentrations of BSA-loaded microspheres. The "programmable" microsphere concentration gradient fibre methodology presented here may enable development of novel alginate scaffolds with the ability to guide tissue regeneration through tightly-controlled release of one or more proteins in highly defined spatio-temporal configurations.

Trilayered polypyrrole (PPy) actuators have high stress density, low modulus and have wide potential biological applications including use in artificial muscles and in limb prosthesis after limb amputation. This article examines the in vivo biocompatibility of actuators in muscle using rabbit models. The actuators were specially designed with pores to encourage tissue in growth; this study also assessed the effect of such pores on the stability of the actuators in vivo. Trilayered PPy actuators were either laser cut with 150 µm pores or left pore-less and implanted into rabbit muscle for 3 days, 2 weeks, 4 weeks and 8 weeks and retrieved subsequently for histological analysis. In a second set of experiments, the cut edges of pores in porous actuator strips were further sealed by PPy after laser cutting to further improve its stability in vivo. Porous actuators with and without PPy sealing of pore edges were implanted intramuscularly for 4 and 8 weeks and assessed with histology. Pore-less actuators incited a mild inflammatory response, becoming progressively walled off by a thin layer of fibrous tissue. Porous actuators showed increased PPy fragmentation and delamination with associated greater foreign body response compared to pore-less actuators. The PPy fragmentation was minimized when the pore edges were sealed off by PPy after laser cutting showing less PPy debris. Laser cutting of the actuators with pores destabilizes the PPy. This can be overcome by sealing the cut edges of the pores with PPy after laser. The findings in this article have implications in future design and manufacturing of PPy actuator for use in vivo.

Biofabrication is the process of transforming materials into systems that reproduce biological structure and function. Previous attempts to create biomimetic systems have often used single materials shaped into limited configurations that do not mimic the heterogeneous structure and properties of many biological tissues. The identification of new bio-inspired materials alongside the development of appropriate fabrication techniques is the key to overcoming the challenge of replicating the functional gradients of these heterogeneous tissues. This paper presents a new extrusion-based gradient printing system that utilizes custom software to control the rates at which two inks are dispensed through a mixing nozzle. The printer was used to fabricate a range of composite materials containing varying blends of a tough alginate/poly(acrylamide) ionic covalent entanglement hydrogel and an acrylated urethane based UV-curable adhesive material. The hard adhesive material acted as particulate reinforcement within the matrix of composites printed with a large hydrogel volume fraction. The composite materials were characterized mechanically and their performance could be modeled with standard composite theory. The platform of a 3D printer allowed these composite materials to be fabricated directly with a smooth and continuous gradient of modulus between the soft hydrogel and harder acrylated urethane material, which may be useful in the development of bio-inspired structures such as artificial tendons.

A series of hydrogel-based inks are developed to print 3D structures capable of reversible shape deformation in response to hydration and temperature. The inks are made of large polymer chains and UV curable monomers which form interpenetrating polymer networks after polymerization. By taking advantage of the long polymer chains in the ink formulations, it is possible to adjust the rheological properties of the inks to enable 3D printing. Hydrogels produced from the inks exhibit robust mechanical performance with their mechanical properties controlled by the nature of the long polymer chains within their networks. In this paper, hydrogel hinges are made from various ink formulations and a simple model is developed to predict their bending characteristics, including the bending curvature and bending angle. This model can be used as a guide to determine optimal parameters for a wide range of materials combination to create all-hydrogel structures that undergo desired shape transitions.

The production, diffusion and preservation of knowledge are the main goals of universities, which are critical nodes for mediating intellectual capital. In recent years, 3D printing (additive manufacturing) technologies are emerging as a possible disruptive or transformative force in the knowledge economy and by extension the material economy as consumers are given the affordance of materializing information into real-world objects. To understand the role universities will play in this potential convergence of the material and knowledge economies, this paper surveys current levels of involvement of tertiary institutions in 3D printing. The paper projects how the materialization of data will affect a range of social dynamics for creators-cum-consumers at different scales: community, region and nation-state and applies case studies to the multilevel perspective (MLP) framework. Studies are considered in three empirical cases: Berlin in Germany, Lancashire in the United Kingdom, and the United States. The research indicates that the National Additive Manufacturing Innovation Institute (NAMII) 'America Makes' Program is a top-down knowledge dissemination program for 3D printing. In contrast, the UK Lancaster University Product Development Unit (LPDU) is a 3D-printing value-network, which has developed organically over a decade of operation. Fablab Berlin is a local initiative loosely coupled with industry and tertiary education providers. The paper proposes a future-oriented conceptual framework to capture a variety of present-day university engagements with additive manufacturing in terms of intellectual capital.

Tissue engineering scaffolds for nerve regeneration, or artificial nerve conduits, are particularly challenging due to the high level of complexity the structure of the nerve presents. The list of requirements for artificial nerve conduits is long and includes the ability to physically guide nerve growth using physical and chemical cues as well as electrical stimulation. Combining these characteristics into a conduit, while maintaining biocompatibility and biodegradability, has not been satisfactorily achieved by currently employed fabrication techniques. Here we present a method combining pultrusion and wet-spinning techniques facilitating incorporation of pre-formed filaments into ionically crosslinkable hydrogels. This new biofabrication technique allows the incorporation of conducting or drug-laden filaments, controlled guidance channels and living cells into hydrogels, creating new improved conduit designs.

Purpose - Company pressure for manufacturers is mounting from two angles: Increasing pressure of global competition, and rapid advancements in technology such as additive manufacturing (AM) that are altering the way that goods are manufactured. The purpose of this paper is to explore the adoption process of AM within a manufacturing system and its business impact. Design/methodology/approach - Research was conducted to collect empirical data at two manufacturing case companies in the North West England. Both cases are located in areas of industrial recovery using AM engineering innovation for value creation. Findings - Early findings showed that the implementation of AM caused a shift in value propositions and the creation of additional value streams (VSs) for the case study companies. AM was shown to compliment and strengthen traditional manufacturing VSs rather than replacing them. Research limitations/implications - Limitations include the generalizability due to the number and location of case companies included in this research. Practical implications - It is worthwhile to explore the opportunities that AM brings with the existing customer base as it has the potential to add unexplored and untapped value. However, managers need to be mindful of the capability and resources required to put the VS into practice. Social implications - Both cases resulted in skill retainment and development due to the implementation of AM. Hence, the innovation contributed to regional economic recovery and business survival. Originality/value - This empirical research is one of the early field explorations focussing on the impact of AM on VS structures. Hence, this paper contributes to the area of technology enhanced manufacturing systems.

The past few years have seen the introduction of a number of 3D and 4D printing techniques used to process tough hydrogel materials. The use of 'color' 3D printing technology where multiple inks are used in the one print allows for the production of composite materials and structures that can further enhance the mechanical performance of the printed hydrogel. This article reviews a number of 3D and 4D printing techniques for fabricating functional hydrogel based devices.

Tissue grafting and organ transplantation are common techniques in modern medicine, but suffer from the widely-reported limitations of constrained supply and the risk of rejection, necessitating a lifetime of immunosuppressant medication [1]. The field of tissue engineering has advanced markedly over the last decade, and engineered tissues are under development for both regenerative medicine applications as well as the formation of accurate in vitro models for the study of fundamental tissue behaviours, disease states and drug discovery. Both biological and synthetic materials have been formed into cell-supporting tissue scaffolds [2,3]. In broad terms, biological materials and particularly extracellular matrix (ECM) components offer superior cell interaction properties, but are challenging to process [4]. Synthetic materials are readily processed, but may lack specific or necessary cell interaction motifs. The fabrication of truly biomimetic regenerative scaffolds is an incredibly complex challenge, one that requires an integrated approach to both biomaterials and biofabrication technologies [5].

3D printing is believed by many to be the next industrial revolution. The technology is already deployed in production. However, supply chain literature is still in its infancy regarding this topic, despite 3D printings radical impact on supply chains. A framework has been developed to assess various aspects that need to be considered when deploying such technology as part of the production process. Literature has been drawn from cross-discipline (e.g. social sciences, engineering, and business). The challenge for businesses will be whether to incur the cost impact today or the opportunity cost of tomorrow if 3D printing is not adopted.

A novel water-dispersible conducting polymer analogous to poly(3,4-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been chemically synthesized in a single reaction in high yield. PEDOT:DS, a new member of the polythiophene family, is composed of a complex between PEDOT and the sulfonated polysaccharide polyanion dextran sulfate. Drop-cast films of aqueous suspensions of the material display a native conductivity of up to 7 ± 1 S cm-1, increasing to 20 ± 2 S cm-1 after treatment with ethylene glycol and thermal annealing. Mass ratios of the precursors NaDS and EDOT were varied from 5:1 to 2:1 and a decrease in the NaDS:EDOT ratio produces tougher, less hygroscopic films of higher conductivity. Ultraviolet-visible spectroelectrochemistry yields spectra typical of PEDOT complexes. Cyclic voltammetry reveals that PEDOT:DS is electrochemically active from -1.0 to 0.8V vs. Ag/Ag+ in acetonitrile, with similar characteristics to PEDOT:PSS. Water dispersions of PEDOT:DS are successfully processed by drop casting, spray coating, inkjet printing and extrusion printing. Furthermore, laser etching of dried films allows the creation of patterns with excellent definition. To assess the cytotoxicity of PEDOT:DS, L-929 cells were cultured with a polymer complex concentration range of 0.002 to 0.2 g l-1 in cell culture medium. No significant difference is found between the proliferation rates of L-929 cells exposed to PEDOT:DS and those in plain medium after 96h. However, PEDOT:PSS shows around 25% less cell growth after 4days, even at the lowest concentration. Taken together, these results suggest PEDOT:DS has exceptional potential as an electromaterial for the biointerface.

This review evaluates hydrogel-forming polymers that are suitable for soft tissue engineering with a focus on materials that can be fabricated using additive manufacturing (3D-printing). An overview of the specific material requirements for hydrogel-based tissue engineering constructs is presented. This is followed by an explanation of the various hydrogel-forming polymer classes that includes a detailed examination of material properties that are critical for extrusion printing. Specifically, mechanisms for hydrogel formation, degradation, and biological response, activity and compatibility are explored. A discussion of extrusion printing strategies for printable hydrogel-forming polymers is then presented in conjunction with a list of considerations to guide future tissue engineering developments.

The brain is an enormously complex organ structured into various regions of layered tissue. Researchers have attempted to study the brain by modeling the architecture using two dimensional (2D) in vitro cell culturing methods. While those platforms attempt to mimic the in vivo environment, they do not truly resemble the three dimensional (3D) microstructure of neuronal tissues. Development of an accurate in vitro model of the brain remains a significant obstacle to our understanding of the functioning of the brain at the tissue or organ level. To address these obstacles, we demonstrate a new method to bioprint 3D brain-like structures consisting of discrete layers of primary neural cells encapsulated in hydrogels. Brain-like structures were constructed using a bio-ink consisting of a novel peptide-modified biopolymer, gellan gum-RGD (RGD-GG), combined with primary cortical neurons. The ink was optimized for a modified reactive printing process and developed for use in traditional cell culturing facilities without the need for extensive bioprinting equipment. Furthermore the peptide modification of the gellan gum hydrogel was found to have a profound positive effect on primary cell proliferation and network formation. The neural cell viability combined with the support of neural network formation demonstrated the cell supportive nature of the matrix. The facile ability to form discrete cell-containing layers validates the application of this novel printing technique to form complex, layered and viable 3D cell structures. These brain-like structures offer the opportunity to reproduce more accurate 3D in vitro microstructures with applications ranging from cell behavior studies to improving our understanding of brain injuries and neurodegenerative diseases. (C) 2015 Elsevier Ltd. All rights reserved.

A smart valve is created by 4D printing of hydrogels that are both mechanically robust and thermally actuating. The printed hydrogels are made up of an interpenetrating network of alginate and poly(N-isopropylacrylamide). 4D structures are created by printing the "dynamic" hydrogel ink alongside other static materials.

In this work we present a centrifugal microfluidic system enabling highly efficient collective trapping and alignment of particles such as microbeads and cells, their multi-colour fluorescent detection and subsequent manipulation by optical tweezers. We demonstrate array-based capture and imaging followed by "cherry-picking" of individual particles, first for fluorescently labelled polystyrene (PS) beads and then for cells. Different cell lines are discriminated based on intracellular as well as surface-based markers.

Common fabrication techniques typically require multiple and complex MEMS processing steps to create 3D electrode architectures. Here we report on the use of Additive Fabrication metal printing based on Selective Laser Melting (SLM) technology to produce 3D titanium interdigitated electrodes. This was used as a platform to deposit polypyrrole and the resultant structure was evaluated for use as a capacitive electrode. We also demonstrate a solid-state interdigitated supercapacitor using a poly(vinyl alcohol) (PVA)-H3PO4 polymer electrolyte.

An additive manufacturing process that combines digital modeling and 3D printing was used to prepare fiber reinforced hydrogels in a single-step process. The composite materials were fabricated by selectively pattering a combination of alginate/acrylamide gel precursor solution and an epoxy based UV-curable adhesive (Emax 904 Gel-SC) with an extrusion printer. UV irradiation was used to cure the two inks into a single composite material. Spatial control of fiber distribution within the digital models allowed for the fabrication of a series of materials with a spectrum of swelling behavior and mechanical properties with physical characteristics ranging from soft and wet to hard and dry. A comparison with the "rule of mixtures" was used to show that the swollen composite materials adhere to standard composite theory. A prototype meniscus cartilage was prepared to illustrate the potential application in bioengineering.

Carrageenan/epoxy amine ionic-covalent entanglement hydrogels were fabricated on a 3D printer. The thermal gel transition behaviour of the biopolymer kappa-carrageenan was exploited to fix the shape of the patterned ink until a covalent polymer network formed by epoxy amine addition chemistry. The printed hydrogels display a work of extension value of 1.4 ± 0.3 MJ m-3.

In this report single-wall carbon nanotubes (SWNTs) were coated onto latex using spray coating to produce a stretchable electrode. The electrochemical properties of the electrode were determined using cyclic voltammetry and electrochemical impedance spectroscopy and galvanostatic charge/discharge tests were also carried out. The impedance and charge/discharge curves of the latex/SWNTs electrode showed good capacitive behavior even after repetitive stretching to 100% strain. The highest capacitance value obtained for the unstretched SWNTs electrode was 119 F g−1 in 1 M Na2SO4 at 5 mV s−1. After the 100th stretch ≈ 80% of the original capacitance value was retained.

Here, we show that graphene oxide (GO) dispersions exhibit unique viscoelastic properties, making them a new class of soft materials. The fundamental insights accrued here provide the basis for the development of fabrication protocols for these two-dimensional soft materials, in a diverse array of processing techniques.

The electrical impedance behavior of gellan gum (GG), GG-carbon nanotube, and GG-carbon nanofiber hydrogel composites is reported. It is demonstrated that the impedance behavior of these gels can be modeled using a Warburg element in series with a resistor. Sonolysis (required to disperse the carbon fillers) does not affect GG hydrogel electrical conductivity (1.2 ± 0.1 mS/cm), but has a detrimental effect on the gel's mechanical characteristics. It was found that the electrical conductivity (evaluated using impedance analysis) increases with increasing volume fraction of the carbon fillers and decreasing water content. For example, carbon nanotube containing hydrogels exhibited a six- to sevenfold increase in electrical conductivity (to 7 ± 2 mS/cm) at water content of 82%. It is demonstrated that at water content of 95 ± 2% the electrical behavior of multiwalled nanotube containing hydrogels transitions (percolates) from transport dominated by ions (owing to GG) to transport dominated by electrons (owing to the carbon nanotube network).

The mechanical characteristics of ionic-covalent entanglement hydrogels consisting of combinations of the biopolymers gellan gum and kappa-carrageenan, and the synthetic polymers polyacrylamide and an epoxy amine were investigated. Compression testing showed that these gels exhibited "double network" behavior, i.e. strong tough gels.

We report on a new technique known as Near Field Electroprinting (NFEP) to fabricate a gelatin hydrogel based array for use as an electrochemical sensor. Using this technique, an array of gelatin fibers one micron in diameter and spaced approximately 100 micron apart, was patterned and subsequently cross-linked. To validate its use as a sensor, the ends of the array were coated in gold to provide electrical connections and a CV was performed using a ferricyanide redox couple. This work opens up the development of printed hydrogel biosensors exploiting the biocompatibility of hydrogel materials.

This paper demonstrates the full centrifugal microfluidic integration and automation of all liquid handling steps of a 7-step fluorescence-linked immunosorbent assay (FLISA) for quantifying nitrate and nitrite levels in whole blood within about 15 min. The assay protocol encompasses the extraction of metered plasma, the controlled release of sample and reagents (enzymes, co-factors and fluorescent labels), and incubation and detection steps. Flow control is implemented by a rotationally actuated dissolvable film (DF) valving scheme. In the valves, the burst pressure is primarily determined by the radial position, geometry and volume of the valve chamber and its inlet channel and can thus be individually tuned over an extraordinarily wide range of equivalent spin rates between 1,000 RPM and 5,500 RPM. Furthermore, the vapour barrier properties of the DF valves are investigated in this paper in order to further show the potential for commercially relevant on-board storage of liquid reagents during shelf-life of bioanalytical, ready-to-use discs.

The plasma separation rate is enhanced significantly, as much as 8 times faster for whole blood, by simple change of the channel geometry in a rotating disc. It was enhanced in the channels with narrower channel widths and larger tilt angles with respect to the radial direction but independent of the channel depth or spin direction. A modified Ponder-Nakamura-Kuroda (PNK) theory could nicely fit all of the experimental data to a linear line, which data were obtained from spinning discs with various channel designs and blood samples with broad hematocrit range. To the best of our knowledge, this is the first investigation of geometry effects on the particle separation rate on a rotating disc and it will potentially contribute to the further performance enhancement of centrifugal microfluidic devices. 2013 Elsevier B.V. All rights reserved.

Printing food seems more like an idea based in Star Trek rather than in the average home. But recent advances in 3D printing (known formally as additive manufacturing) are driving the concept closer to reality. With everything from printed metal airplane wings to replacement organs on the horizon, could printed food be next? And how will we feel when it's served at the table?

Analysis of metal ions is critical for chemical monitoring, environmental and clinical applications [1]. For lab-on-achip technologies each circumstance can necessitate the use of different analysis techniques. We therefore developed a more universal platform based a novel spiropyran-conducting polymer (pBSP7) complex that takes advantage of both base chemistries to act as a dual control stimuli responsive material. We utilize this material for the first time to integrate a common chip architecture with multiple analytical techniques to examine the photochemical and electrochemical and sensing of species in solution.

This paper demonstrates the full centrifugal microfluidic integration and automation of all liquid handling steps of a 7-step fluorescence-linked immunosorbent assay (FLISA) for quantifying nitrate and nitrite levels in whole blood within about 15 min. The assay protocol encompasses the extraction of metered plasma, the controlled release of sample and reagents (enzymes, co-factors and fluorescent labels), and incubation and detection steps. Flow control is implemented by a rotationally actuated dissolvable film (DF) valving scheme. In the valves, the burst pressure is primarily determined by the radial position, geometry and volume of the valve chamber and its inlet channel and can thus be individually tuned over an extraordinarily wide range of equivalent spin rates between 1,000 RPM and 5,500 RPM. Furthermore, the vapour barrier properties of the DF valves are investigated in this paper in order to further show the potential for commercially relevant on-board storage of liquid reagents during shelf-life of bioanalytical, ready-to-use discs. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Gun laws have been back in the media recently due, largely, to the horrific events at Sandy Hook Elementary School on December 14, 2012 which claimed the lives of 20 children and six adults. In response President Obama has just unveiled gun control proposals.

Over the past two decades, centrifugal microfluidic systems have successfully demonstrated their capability for robust, high-performance liquid handling to enable modular, multipurpose lab-on-a-chip platforms for a wide range of lifescience applications. Beyond the handling of homogeneous liquids, the unique, rotationally controlled centrifugal actuation has proven to be specifically advantageous for performing cell and particle handling and assays. In this review we discuss technologies to implement two important steps for cell handling, namely separation and capturing/counting.

This work describes the first use of a wireless paired emitter detector diode device (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on an ionogel sensing area combined with a low-cost optical sensor, is applied for quantitative pH and qualitative turbidity monitoring of water samples at point-of-need. The autonomous capabilities of the PEDD system, combined with the portability and wireless communication of the full device, provide the flexibility needed for on-site water testing. Water samples from local fresh and brackish sources were successfully analysed using the device, showing very good correlation with standard bench-top systems.

In this article we introduce a novel technology that utilizes specialized water dissolvable thin films for valving in centrifugal microfluidic systems. In previous work (William Meathrel and Cathy Moritz, IVD Technologies, 2007), dissolvable films (DFs) have been assembled in laminar flow devices to form efficient sacrificial valves where DFs simply open by direct contact with liquid. Here, we build on the original DF valving scheme to leverage sophisticated, merely rotationally actuated vapour barriers and flow control for enabling comprehensive assay integration with low-complexity instrumentation on "lab-on-a-disc" platforms. The advanced sacrificial valving function is achieved by creating an inverted gas-liquid stack upstream of the DF during priming of the system. At low rotational speeds, a pocket of trapped air prevents a surface-tension stabilized liquid plug from wetting the DF membrane. However, high-speed rotation disrupts the metastable gas/liquid interface to wet the DF and thus opens the valve. By judicious choice of the radial position and geometry of the valve, the burst frequency can be tuned over a wide range of rotational speeds nearly 10 times greater than those attained by common capillary burst valves based on hydrophobic constrictions. The broad range of reproducible burst frequencies of the DF valves bears the potential for full integration and automation of comprehensive, multi-step biochemical assay protocols. In this report we demonstrate DF valving, discuss the biocompatibility of using the films, and show a potential sequential valving system including the on-demand release of on-board stored liquid reagents, fast centrifugal sedimentation and vigorous mixing; thus providing a viable basis for use in lab-on-a-disc platforms for point-of-care diagnostics and other life science applications.

This work demonstrates the design and fabrication of an all cyclo-olefin polymer based microfluidic device capable of capturing magnetic beads and performing electrochemical detection in a series of gold electrodes. The size of chip is of a microscope slide and features six independent measuring cells formultianalyte detection purposes. The aim of this work is to show that rapid prototyping techniques can be instrumental in the development of novel bioassays, particularly in clinical diagnosis applications. We show the successful determination of troponin-T, a cardiac disease marker, in the clinically relevant range of 0.05–1.0 ng/mL. This methodology achieves a detection limit of 0.017 ng/mL in PBS solutions, and is capable of detecting less than 1 ng/mL in a 1:50 human serum dilution.

We present a novel, low-resource fabrication and assembly method for creating disposable amperometric detectors in hybrid paper-polymer devices. Currently, mere paper-based microfluidics is far from being able to achieve the same level of process control and integration as state-of-the-art microfluidic devices made of polymers. To overcome this limitation, in this work both substrate types are synergistically combined through a hybrid, multi-component/multi-material system assembly. Using established inkjet wax printing, we transform the paper into a profoundly hydrophobic substrate in order to create carbon electrodes which are simply patterned from carbon inks via custom made adhesive stencils. By virtue of the compressibility of the paper substrate, the resulting electrodeon- paper hybrids can be directly embedded in conventional, 3D polymeric devices by bonding through an adhesive layer. This manufacturing scheme can be easily recreated with readily available off-the-shelf equipment, and is extremely cost-efficient and rapid with turn-around times of only a few hours.

In traditional centrifugal microfluidic platforms pumping is restricted to outward fluid flow, resulting in potential real estate issues for embedding complex microsystems. To overcome the limitation, researchers utilize hydrophilic channels to force liquids short distances back toward the disk center. However, most polymers used for CD fabrication are natively hydrophobic, and creating hydrophilic conditions requires surface treatments/specialized materials that pose unique challenges to manufacturing and use. This work describes a novel technology that enjoys the advantages of hydrophilic fluidics on a hydrophobic disk device constructed from untreated polycarbonate plastic. The method, termed suction-enhanced siphoning, is based on exploiting the non-linear hydrostatic pressure profile and related pressure drop created along the length of a rotating microchannel. Theoretical analysis as well as experimental validation of the system is provided. In addition, we demonstrate the use of the hydrostatic pressure pump as a new method for priming hydrophobicbased siphon structures. The development of such techniques for hydrophobic fluidics advances the capabilities of the centrifugal microfluidic platform while remaining true to the goal of creating disposable polymer devices using feasible manufacturing schemes.

A novel active valving technique, whereby paraffin wax plugs in microchannels on a centrifugal microfluidic platform are actuated using focused infrared (IR) radiation is demonstrated in this report. Microchannels were simultaneously or sequentially opened using a stationary IR source by forming wax plugs with similar or differing melting points. The presented wax plugs offer key advantages over current active valving techniques, including a less involved fabrication procedure, a simpler actuation process, and the ability to multiplex experiment with active valves. In addition, a new technique for automated liquid reagent storage and release on the microfluidic disc platform, based on the formation and removal of a wax layer, is demonstrated. Overall, the techniques presented in this report offer novel methods for liquid handling, separation, and storage on the centrifugal microfluidic disc platform.