Search

Sensitive detection of near-infrared (NIR) light could enable several important applications in optical communications, quality control, and sensing in industries, such as automotive and aerospace, and human–machine interface (HMI) biometrics. In this work, we demonstrate NIR photodetectors based on an organic bulk heterojunction absorbing layer with state-of-the-art performance across critical response metrics. The external quantum efficiency spectrum of the devices presented extends from 500 nm to approximately 900 nm covering both visible and NIR wavelengths. The organic photodiodes (OPDs) show specific detectivities of around 7.4 × 10 11 Jones, which is comparable to the state of the art organic devices. Furthermore, the NIR OPD devices show a linear dynamic range (LDR) of ∼ 74 dB. [ABSTRACT FROM AUTHOR]

Background: Teamwork influences health care quality and patient safety. Yet, validated instruments for assessing teamwork in Colombia are lacking. Purpose: The purpose of this study was to validate the Spanish version of the TeamSTEPPS-Teamwork Perceptions Questionnaire (T-TPQ-S) for the Colombian health care context. Methods: The T-TPQ-S underwent translation, cultural adaptation, and comprehensive psychometric testing, including reliability and confirmatory factor analyses and item difficulty and discrimination analyses. Results: The T-TPQ-S demonstrated high internal consistency and excellent fit to the theoretical model. Item discrimination was within expected ranges, with response thresholds displaying an ascending order. The tool better differentiated subjects with low and high teamwork perceptions. Conclusions: The T-TPQ-S is an effective, reliable, and valid instrument for assessing teamwork perception among Colombian health care workers. [ABSTRACT FROM AUTHOR]

Distributed sensors and electronics can be used in agriculture to optimize crop management and improve environmental outcomes. Electronic devices in these outdoor spaces require medium to long range (>1m) wireless communication of data over several weeks or months, which in turn requires high conductivity (1 × 105 Sm−1) antennas. Printed bioinert or ecoresorbable conductors, comprising carbon, magnesium, or zinc fillers, typically exhibit conductivity on the order of 10–1000 Sm−1 and lifetimes from a few hours to a few days. A print‐based fabrication process for chemically treated zinc traces, which achieves conductivity of up to 6 × 105 Sm−1 is reported here. The ink formulation uses a non‐water‐soluble soil biodegradable polycaprolactone binder. The ink and printing processes reported here led to stable conductive traces that are used in ultra high frequency radio frequency identification (UHF‐RFID) folded dipole antennas operating at 915 MHz. The conductivity of the printed traces is maintained for over 70 days in ambient environments when traces are protected by a biodegradable beeswax encapsulation layer. [ABSTRACT FROM AUTHOR]

Purpose: Coil arrays are connected to the main MRI system with long, shielded coaxial cables. RF coupling of these cables to the main transmit coil can cause high shield currents, which pose risks of heating and RF burns. High‐blocking resonant RF traps are placed at distinct positions along cables to mitigate these currents. Traditional traps are designed to be stiff to avoid changes in their resonant frequency, hindering the overall system flexibility. Instead of using a few high‐blocking traps, we propose the use of caterpillar traps—a distributed system of small, elastic traps that cover the full length of cables. Methods: We leverage an array of resonant toroids as traps, forming a caterpillar‐like structure whereby bending only impacts individual traps minimally. Benchtop measurements are used to determine the blocking of caterpillar traps and show their robustness to bending. We also compare an anterior array system cable covered with caterpillar traps to a commercial cable with B1+ and heating measurements. Results: Benchtop experiments with caterpillar traps demonstrate high robustness to bending. B1+ mapping experiments of an anterior array cable show improved blocking and flexibility compared to a commercial cable. Conclusion: Caterpillar traps provide sufficient attenuation to shield currents while allowing cable flexibility. Our distributed design can provide high blocking efficiency at different positions and orientations, even in cases where commercial cable traps cannot. [ABSTRACT FROM AUTHOR]

Purpose: To describe a digital fabrication method used for custom MRI receive coils with vacuum forming and electroless copper plating. Methods: Our process produces intricate copper traces on curved surfaces. A three‐dimensional scan of a desired anatomy is obtained and used to design coil elements. The layout is predistorted with a self built simulation of the vacuum forming process and the geometric overlaps are tested with electromagnetic simulation software. The desired coil geometry is patterned onto a polycarbonate sheet by sandblasting through a tape mask. The sandblasted areas are then catalyzed with a palladium‐tin solution and vacuum formed. The catalyzed, three‐dimensional part is placed into a custom built plating tank and copper plated. Electronic components are attached to the copper traces to form resonant receive coils. The methods described here are demonstrated and tested with an 8 channel visual cortex coil array. Results: The prototype coils exhibit quality factor ratios higher than three, indicating body noise dominance. The coil array shows high signal‐to‐noise ratio (SNR) near the periphery of a head shaped phantom. In vivo images with up to 0.37×0.37×0.67 mm3$$ 0.37\times 0.37\times 0.67\;{\mathrm{mm}}^3 $$ spatial resolution were acquired on a human volunteer. Conclusion: This work presents the first example of vacuum formed coils with direct electroless copper plating. Our fabrication method results in coil arrays that are in close proximity to the body. This methods described here may enable the rapid development of a set of coils of different sizes for applications including longitudinal fMRI studies and MR‐guided therapies. [ABSTRACT FROM AUTHOR]

Medical electrophysiological sensors that can study the body and diagnose diseases depend on consistently low impedance electrode–skin interfaces. Clinical‐standard wet electrodes use hydrogels and skin abrasion to improve the interface and thus the recorded signal quality. These electrodes are challenging to self‐administer and impede in‐home care. Wearable dry electrodes are more practical; however, they show higher impedances than wet electrodes and are costly to customize. This work presents a fabrication method for rapidly producing low impedance, anatomically fit dry electrodes that do not require hydrogels. By using electroless copper and gold plating with 3D printing, biocompatible electrodes can be optimized for individuals at a fraction of the cost of existing vacuum deposition‐based techniques. Example 3D dry electrodes made with this process are evaluated alongside clinical‐standard devices in typical scenarios to compare electrical performance and comfort. The resulting dry electrodes exhibit an average electrode‐skin impedance of 66.7 kΩ at 50 Hz and DC offset of −20 mV without any hydrogel, which, when area normalized, is within the range achieved by wet electrodes without skin abrasion. [ABSTRACT FROM AUTHOR]

Advances in printing techniques have enabled a new generation of low‐cost and large‐area flexible electronics. However, in applications where a combination of printed components is required, multiple fabrication processes and subsequent integration can be complex and time consuming. Additionally, these applications require devices to be stacked atop each other, reducing overall mechanical flexibility. In this work, surface‐energy‐patterning (SEP) is used to enable simultaneous blade coating of organic photodiode (OPD) and organic light‐emitting diode (OLED) films side‐by‐side. The result is dual functionality on a single flexible substrate. Various active layer solution concentrations are investigated to optimize active layer thicknesses and consequently optimize the performance of each device. A peak spectral responsivity of 0.33 A W−1 at 800 nm is achieved for optimized OPDs and a maximum luminance of 7000 cd m−2 is achieved for optimized OLEDs at an applied bias of 8 V. Overall, this technique enables the printing of two functionally distinct devices in a single step without compromising the performance of either device. [ABSTRACT FROM AUTHOR]

Purpose: To present a reproducible methodology for building an anatomy mimicking phantom with targeted T1 and T2 contrast for use in quantitative magnetic resonance imaging. Methods: We propose a reproducible method for creating high‐resolution, quantitative slice phantoms. The phantoms are created using gels with different concentrations of NiCl2 and MnCl2 to achieve targeted T1 and T2 values. We describe a calibration method for accurately targeting anatomically realistic relaxation pairs. In addition, we developed a method of fabricating slice phantoms by extruding 3D printed walls on acrylic sheets. These procedures are combined to create a physical analog of the Brainweb digital phantom. Results: With our method, we are able to target specific T1/T2 values with less than 10% error. Additionally, our slice phantoms look realistic since their geometries are derived from anatomical data. Conclusion: Standardized and accurate tools for validating new techniques across sequences, platforms, and different imaging sites are important. Anatomy mimicking, multi‐contrast phantoms designed with our procedures could be used for evaluating, testing, and verifying model‐based methods. [ABSTRACT FROM AUTHOR]

Electronic skins (e‐skins) that mimic the thermosensation and mechanosensation functionalities of natural skin are highly desired for the emerging fields of prosthetics and robotics. Advances in the materials and architecture of e‐skins have been made; nevertheless, sensing mechanism innovations are rarely explored. Here, inspired by the skin sensory behaviors, a single potentiometric sensing scheme for both thermosensation and mechanosensation functionalities are presented. Through careful materials selection, component optimization, and structure configuration, the coupling effect between thermosensation and mechanosensation can be significantly minimized. Such a potentiometric sensing scheme enables one to create a new class of energy‐efficient e‐skin with distinctive characteristics that are highly analogous to those of natural human skin. The e‐skin reported here features ultralow power consumption (at nanowatt level), greatly simplified operation (only voltage output), ultrahigh sensitivity (non‐contact sensing capability), all‐solution‐processing fabrication, and, more importantly, good capability for simultaneous monitoring/mapping of both thermal and mechanical stimulations. In addition to proposing a new sensory mechanism, integration of the dual‐functional e‐skin with a soft robotic gripper for object manipulation is demonstrated. The presented concise yet efficient sensing scheme for both thermosensation and mechanosensation opens up previously unexplored avenues for the future design of skin prosthetics, humanoid robotics, and wearable electronics. [ABSTRACT FROM AUTHOR]

In the past few years it has been demonstrated that electroencephalography (EEG) can be recorded from inside the ear (in-ear EEG). To open the door to low-profile earpieces as wearable brain-computer interfaces (BCIs), this work presents a practical in-ear EEG device based on multiple dry electrodes, a user-generic design, and a lightweight wireless interface for streaming data and device programming. The earpiece is designed for improved ear canal contact across a wide population of users and is fabricated in a low-cost and scalable manufacturing process based on standard techniques such as vacuum forming, plasma-treatment, and spray coating. A 2.5 × 2.5 cm2 wireless recording module is designed to record and stream data wirelessly to a host computer. Performance was evaluated on three human subjects over three months and compared with clinical-grade wet scalp EEG recordings. Recordings of spontaneous and evoked physiological signals, eye-blinks, alpha rhythm, and the auditory steady-state response (ASSR), are presented. This is the first wireless in-ear EEG to our knowledge to incorporate a dry multielectrode, user-generic design. The user-generic ear EEG recorded a mean alpha modulation of 2.17, outperforming the state-of-the-art in dry electrode in-ear EEG systems. [ABSTRACT FROM AUTHOR]

Light absorption in oxygenated and deoxygenated blood varies appreciably over the visible and near‐infrared spectrum. Pulse oximeters use two distinct wavelengths of light to measure oxygen saturation SpO2 of blood. Currently, light‐emitting diodes (LEDs) are used in oximeters, which need additional components to drive them and negatively impact the overall size of the sensor. In this work, an ambient light oximeter (ALO) is demonstrated, which can measure photoplethysmography signals and SpO2 using various kinds of ambient light, avoiding the use of LEDs. Spectral filters are combined with organic photodiodes to create the ALO with sensitivity peaks at green (525 nm), red (610 nm), and near‐infrared (740 nm) wavelengths. Finally, the wearable ALO is used to measure photoplethysmography signals and SpO2 on the index finger in different indoor and outdoor lighting conditions and the measurements are validated with commercial pulse oximeters under normal and ischemic conditions. [ABSTRACT FROM AUTHOR]

Abstract: Solution‐processibility is one of the distinguished traits of organic light‐emitting diodes (OLEDs) compared to existing solid‐state LED technologies. It allows new opportunities which can simplify the fabrication and potentially reduce the cost of manufacturing process. Emission area patterning is one of the crucial fabrication steps and it usually involves subtractive methods, such as photolithography or etching. Here, printing techniques are used to pattern the emission area of blade‐coated OLED layers. The print qualities of a number of printing schemes are characterized and compared. Spray coating and screen printing are used to deposit dielectrics with desired patterns on the OLED layers. At luminance of 1000 cd m−2 the OLEDs patterned using spray‐coated and screen‐printed dielectric show current density of 8.2 and 10.1 mA cm−2, external quantum efficiency (EQE) of 2.1% and 2.1%, and luminous efficacy of 5.5 and 6.3 lm W−1, respectively. The OLED characteristics and features of each printing scheme in depositing the dielectric layer are discussed. The printing methods are further applied to demonstrate displays with complex shapes and a seven‐segment display. [ABSTRACT FROM AUTHOR]

Purpose To develop methods for characterizing materials used in screen-printed MRI coils and improve signal-to-noise ratio (SNR) with new lower-loss materials. Methods An experimental apparatus was created to characterize dielectric properties of plastic substrates used in receive coils. Coils were fabricated by screen printing conductive ink onto several plastic substrates. Unloaded and sample loaded quality factor (QUnloaded/QLoaded) measurements and scans on a 3T scanner were used to characterize coil performance. An experimental method was developed to describe the relationship between a coil's QUnloaded and the SNR it provides in images of a phantom. In addition, 3T scans of a phantom and the head of a volunteer were obtained with a proof-of-concept printed eight-channel array, and the results were compared with a commercial 12-channel array. Results Printed coils with optimized substrates exhibited up to 97% of the image SNR when compared with a traditional coil on a loading phantom. QUnloaded and the SNR of coils were successfully correlated. The printed array resulted in images comparable to the quality given by the commercial array. Conclusion Using the proposed methods and materials, the SNR of printed coils approached that of commercial coils while using a new fabrication technique that provided more flexibility and close contact with the patient's body. Magn Reson Med 78:775-783, 2017. © 2016 International Society for Magnetic Resonance in Medicine [ABSTRACT FROM AUTHOR]

The interfacing of soft and hard electronics is a key challenge for flexible hybrid electronics. Currently, a multisubstrate approach is employed, where soft and hard devices are fabricated or assembled on separate substrates, and bonded or interfaced using connectors; this hinders the flexibility of the device and is prone to interconnect issues. Here, a single substrate interfacing approach is reported, where soft devices, i.e., sensors, are directly printed on Kapton polyimide substrates that are widely used for fabricating flexible printed circuit boards (FPCBs). Utilizing a process flow compatible with the FPCB assembly process, a wearable sensor patch is fabricated composed of inkjet-printed gold electrocardiography (ECG) electrodes and a stencil-printed nickel oxide thermistor. The ECG electrodes provide 1 mV p- p ECG signal at 4.7 cm electrode spacing and the thermistor is highly sensitive at normal body temperatures, and demonstrates temperature coefficient, α ≈ -5.84% K-1 and material constant, β ≈ 4330 K. This sensor platform can be extended to a more sophisticated multisensor platform where sensors fabricated using solution processable functional inks can be interfaced to hard electronics for health and performance monitoring, as well as internet of things applications. [ABSTRACT FROM AUTHOR]

Bioelectronic interfaces require electrodes that are mechanically flexible and chemically inert. Flexibility allows pristine electrode contact to skin and tissue, and chemical inertness prevents electrodes from reacting with biological fluids and living tissues. Therefore, flexible gold electrodes are ideal for bioimpedance and biopotential measurements such as bioimpedance tomography, electrocardiography (ECG), electroencephalography (EEG), and electromyography (EMG). However, a manufacturing process to fabricate gold electrode arrays on plastic substrates is still elusive. In this work, a fabrication and low-temperature sintering (≈200 °C) technique is demonstrated to fabricate gold electrodes. At low-temperature sintering conditions, lines of different widths demonstrate different sintering speeds. Therefore, the sintering condition is targeted toward the widest feature in the design layout. Manufactured electrodes show minimum feature size of 62 μm and conductivity values of 5 × 10 6 S m−1. Utilizing the versatility of printing and plastic electronic processes, electrode arrays consisting of 31 electrodes with electrode-to-electrode spacing ranging from 2 to 7 mm are fabricated and used for impedance mapping of conformal surfaces at 15 kHz. Overall, the fabrication process of an inkjet-printed gold electrode array that is electrically reproducible, mechanically robust, and promising for bioimpedance and biopotential measurements is demonstrated. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Salud Pública is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper discusses the concept of using the threshold-voltage shift in disordered-semiconductor-based thin-film transistors to measure the time of occurrence of randomly spaced events of interest. We call the experimental circuit an "analog clock." The analog clock is shown to be accurate while, at the same time, being simple in design using just one transistor. [ABSTRACT FROM AUTHOR]

We explore charge generation and recombination kinetics quantitatively in a model polymeric semiconductor ternary system. Resonance energy transfer from a polyfluorene copolymer backbone to perylene-substituted side chains selectively excites the dye. In a blend with an alkoxy-substituted poly-p-phenylenevinylene, photoinduced charge transfer is observed. A comparison of picosecond time scale and quasisteady-state charge generation efficiencies allows measurement of the fraction of charges that survive rapid geminate recombination. This simple procedure allows the unraveling of the role played by recombination kinetics in the device. [ABSTRACT FROM AUTHOR]

Flexible pressure sensors with high sensitivity, broad working range, and good scalability are highly desired for the next generation of wearable electronic devices. However, manufacturing of such pressure sensors still remains challenging. A large‐area compliant and cost‐effective process to fabricate high‐performance pressure sensors via a combination of mesh‐molded periodic microstructures and printed side‐by‐side electrodes is presented. The sensors exhibit low operating voltage (1 V), high sensitivity (20.9 kPa−1), low detection limit (7.4 Pa), fast response/recovery time (23/18 ms), and excellent reliability (over 10 000 cycles). More importantly, they exhibit ultra‐broad working range (7.4–1 000 000 Pa), high tunability, large‐scale production feasibility, and significant advantage in format miniaturization and creating sensor arrays with self‐defined patterns. The versatility of these devices is demonstrated in various human activity monitoring and spatial pressure mapping as electronic skins. Furthermore, utilizing printing methods, a flexible smart insole with a high level of integration for both foot pressure and temperature mapping is demonstrated. The scalable and cost‐effective manufacturing along with the good comprehensive performance of the pressure sensors makes them very attractive for future development of wearable smart devices and human–machine interfaces. [ABSTRACT FROM AUTHOR]

On page 1004, A. C. Arias and co‐workers demonstrate inkjet‐printed gold electrode arrays on plastic substrates—with a special focus on laser‐cut freestanding electrodes—that exhibit excellent mechanical compliance. Taking advantage of the low‐cost and large‐area manufacturing techniques, these mechanically flexible and chemically inert electrode arrays are promising for novel wearable medical sensing applications. [ABSTRACT FROM AUTHOR]

Additive and low-temperature printing processes enable the integration of diverse electronic devices, both power-supplying and power-consuming, on flexible substrates at low cost. Production of a complete electronic system from these devices, however, often requires power electronics to convert between the various operating voltages of the devices. Passive components-inductors, capacitors, and resistors-perform functions such as filtering, short-term energy storage, and voltage measurement, which are vital in power electronics and many other applications. In this paper, we present screen-printed inductors, capacitors, resistors and an RLC circuit on flexible plastic substrates, and report on the design process for minimization of inductor series resistance that enables their use in power electronics. Printed inductors and resistors are then incorporated into a step-up voltage regulator circuit. Organic light-emitting diodes and a flexible lithium ion battery are fabricated and the voltage regulator is used to power the diodes from the battery, demonstrating the potential of printed passive components to replace conventional surface-mount components in a DC-DC converter application. [ABSTRACT FROM AUTHOR]

In this article the author offers information of potentiometric mechanotransduction mechanism for novel electronic skins. Topics discussed include scientists have attempted to recreate skin functions and develop electronic skins (e-skins) based on active and passive sensing mechanisms; and mechanotransduction mechanism has broad impact on robotics, prosthetics, and health care by providing a much improved human-machine interface.