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Abstract Photodetectors sensing the short‐wave infrared (SWIR) region have great potential due to their significant advantages in a variety of applications because SWIR light possesses both characteristics of visible light and infrared light. Among them, devices using photodetectors to mimic synaptic dynamics and functions have received a great deal of attention due to their capabilities to implement simplified neural systems. However, it is essential to develop synaptic devices that can operate fast with low energy consumption for more efficient implementation of neural systems. Here, a flexible InGaAs synaptic phototransistor with a fast operation speed of under 1 ms and low energy consumption in the atto joule level is developed to femto joule level which is superior to biological synapses (50 ms, 1–100 fJ). By using InGaAs which has high carrier mobility as a channel layer, weak light, and short optical pulse width, fast operation speed in the SWIR region with low energy consumption is obtained. Moreover, the devices demonstrate synaptic behaviors such as “excitatory post synaptic current”, “paired‐pulse facilitation”, “short term plasticity”, “long term plasticity”, and “learning‐experience behavior” as neuro‐synaptic applications. These results provide the possibilities for implementation of complex synaptic functions with fast speed and low power SWIR synaptic phototransistors.

In this study, we demonstrated low leakage current and high mobility thin body (In)GaSb p-FETs. Through the optimization of the V/III ratio during the epitaxial growth, we achieved a highly insulating bottom Al0.95Ga0.05Sb barrier, which eliminates the junction leakage. We also suppressed the interface trap-assisted surface leakage current by introducing In0.53Ga0.47As surface passivation on the GaSb channel. Furthermore, GaSb/InGaSb/GaSb quantum well (QW) channel structure provided significant improvement in effective mobility ( ${\mu }_{\mathrm{ eff}}$ ) characteristics. As a result, the fabricated devices showed the lowest off-leakage current ( ${I} _{\mathrm{ off}}$ ), subthreshold slope ( ${S}$ . ${S}$ .) and high $\mu _{\mathrm{ eff}}$ among reported GaSb p-MOSFETs.

Self-heating has emerged as an important performance/reliability challenge for modern MOSFETs. The challenge is further acerbated for III-V transistors, especially when integrated monolithically in a 3-D platform for applications in ultrafast logic, imagers, etc. A key challenge is the difficulty of heat-dissipation through the ultra-thin channels needed to ensure electrostatic integrity of scaled transistors. In this paper, we demonstrate an innovative use of a heat-dissipating shunt of Ni-InGaAs on InGaAs(111) in the S/D extension region, as well as the use of high-conductivity Mo contact to simultaneously improve electrical and thermal stability and heat dissipation in III-V transistors, such that the peak channel temperature is reduced by as much as 25%-30%. Given the exponential temperature sensitivity of transistor reliability, heat shunts will improve transistor lifetime significantly.

Herein, an approach to form high‐quality GaAs‐based flexible photodetectors (PDs) is first demonstrated by metal wafer bonding (MWB) and high‐throughput epitaxial lift‐off (ELO) with encapsulated thermally grown silicon dioxide (t‐SiO2) for chronic biomedical implants. The flexible GaAs PDs demonstrate responsivity over a wide range of visible and near‐infrared wavelengths. Regarding certain diagnoses, high‐performance PDs are essential for precise treatments with long‐term optoelectronic implants, and the long‐term stability and reliable encapsulation of GaAs PDs will play a major role when optoelectronics are injected into biofluids. t‐SiO2, as an encapsulation barrier, is stable without increasing the leakage current for over 120 h in phosphate‐buffered saline (PBS) at 70 °C. By Arrhenius scaling, the device shows a 700‐day lifetime with stable operation in a biofluid at 37 °C. Finally, by measuring the mass of arsenic using an inductively coupled plasma mass spectrometer (ICP/MS), the t‐SiO2 encapsulation barrier is capable of preventing toxic elements from leaching out to surrounding tissues. The technology may provide approaches based on III–V materials for expanding high‐performance optoelectronic devices to biomedical implants, namely, a broad range of high‐resolution retinal prostheses for blindness or the integration for measuring physiological parameters, such as tissue oxygenation and neural activity in the cerebral cortex.

We demonstrate, for the first time, GaAs thin film solar cells epitaxially grown on a Si substrate using a metal wafer bonding and epitaxial lift-off process. A relatively thin 2.1 μm GaAs buffer layer was first grown on Si as a virtual substrate, and a threading dislocation density of 1.8 × 107 cm−2 was achieved via two In0.1Ga0.9As strained insertion layers and 6× thermal cycle annealing. An inverted p-on-n GaAs solar cell structure grown on the GaAs/Si virtual substrate showed homogenous photoluminescence peak intensities throughout the 2″ wafer. We show a 10.6% efficient GaAs thin film solar cell without anti-reflection coatings and compare it to nominally identical upright structure solar cells grown on GaAs and Si. This work paves the way for large-scale and low-cost wafer-bonded III-V multi-junction solar cells.

Abstract Background South Korean government is currently in progress of expanding the coverage of telemedicine projects as part of an attempt to vitalize service industry, but is facing fierce opposition from KMA. Practice of telemedicine requires sufficient discussions among related parties. Although the participation of medical specialists is important, agreement from the public is essential. Methods Three main tertiary care centers in Seoul were selected for data collection. A total of 224 patients (patients n = 180, patient guardian n = 44) and medical professionals (n = 41) were selected using simple random sampling. Mixed method of quantitative survey and qualitative semi-interview was used. Results This study analyzed patients’ and medical professionals’ perception about the application of telemedicine in cardiology ward in tertiary care centers to provide baseline data when developing and applying telemedicine services. Results implied high need for encouraging telemedicine projects in order to appeal needs among population by providing experience (p

In this paper, approaches to obtain the sub-kT/q non-hysteretic operation mode in negative capacitance (NC) field-effect-transistors for a wide band of applied gate voltages, using capacitance matching, were systematically investigated using TCAD simulation. Unlike certain previous studies, in which the desired operation conditions were received for specific structures and materials, this study presents for the first time a general approach for matching arbitrary MOSFETs with various ferroelectric (FE) materials. This study shows that depending on the initial capacitance matching which represents the best possible subthreshold slope for the preliminary chosen base structure and FE material, any further optimization process can be different. Additionally, for the first time, FE materials were grouped with respect to the shape of their C-V curves in the NC region. This paper shows that with respect to the base structure, certain types of FEs are more preferable to obtain the sub-kT/q operation in a non-hysteretic manner for the wide band of applied voltages. In addition, the impacts of various parameters including the depletion capacitance, supply voltage, gate oxide capacitance, buried oxide capacitance on the capacitance matching were systematically investigated.

Monolithic 3-D integration has emerged as a promising technological solution for traditional transistor scaling limitations and interconnection bottleneck. The challenge we must overcome is a processing temperature limit for top side devices in order to ensure proper performance of bottom side devices. To solve this problem, we developed a low temperature III-V and Ge layer stacking process using wafer bonding and epitaxial lift-off, since these materials can be processed at a low temperature and provide extended opportunity/functionality (sensor, display, analog, RF, etc.) via heterogeneous integration. In this paper, we discuss technology for integrating III-V and Ge materials and its applicability to CMOS, thin film photodiodes, mid-infrared photonics platforms, and MicroLED display integration for creating the ultimate 3-D chip of the future.

Obstructive sleep apnea (OSA) and bruxism are widely recognized as common forms of sleep obstruction in modern everyday life. The most representative and conventional treatment method using continuous positive airway pressure has a critical problem owing to its high inconvenience. A relatively modern alternative solution is the mandibular advancement device, but it still has no monitoring function for patient compliance. Therefore, this research proposes Sleep Guard (s-Guard), a multisensor embedded OSA monitoring intraoral appliance device based on Internet-of-Things technology. Relevant health information monitoring sensors, such as temperature, gyroscope, accelerometer, and SpO2 sensors, were embedded for real-time health monitoring. Results showed an average transmission speed of 91,870.19 bytes per second, a successful connection check rate of 100%, and a wireless data stream error rate of 0.1%. Overall, the actual speed, connection, and error test results revealed the robust functioning of s-Guard in real monitoring scenarios. This research is envisioned to greatly enhance patient compliance when treating OSA or bruxism and is also expected to motivate other sensors to be embedded in our proposed model for the application of other disease areas.

The realization of a silicon optical phase shifter marked a cornerstone for the development of silicon photonics, and it is expected that optical interconnects based on the technology relax the explosive datacom growth in data centers. High-performance silicon optical modulators and switches, integrated into a chip, play a very important role in optical transceivers, encoding electrical signals onto the light at high speed and routing the optical signals, respectively. The development of the devices is continuously required to meet the ever-increasing data traffic at higher performance and lower cost. Therefore, heterogeneous integration is one of the highly promising approaches, expected to enable high modulation efficiency, low loss, low power consumption, small device footprint, etc. Therefore, we review heterogeneously integrated optical modulators and switches for the next-generation silicon photonic platform.

Though lubricant emulsions have been widely used in many industrial processes, various human health hazards have been reported. Conducting a systematic toxicity study on emulsions is difficult since emulsions contain multiple chemical compounds, and hydrophobic compounds form complex emulsion particles via surfactants. For a quantitative toxicity study, we developed a high-throughput imaging system using zebrafish and conducted a large scale in vivo toxicity assay of lubricant emulsion and their common ingredients. By computing the locomotion activity of zebrafish from captured time-lapse images, we could quantify the degree of relative toxicity of 29 chemicals. The changes in the locomotion activity over time were observed to vary significantly depending on emulsions, indicating that the degree of toxicity of the commercial products was very diverse. We found that primary ethanolamines were more toxic than secondary or tertiary ethanolamines, and several factors, such as alkyl chain length, EO mole, test concentration, and emulsion particle size, affected toxicity.

Adherence to medication plays a crucial role in the effective management of chronic diseases. However, patients often miss their scheduled drug administrations, resulting in suboptimal disease control. Therefore, we propose an implantable device enabled with automated and precisely timed drug administration. Our device incorporates a built-in mechanical clock movement to utilize a clockwork mechanism, i.e., a periodic turn of the hour axis, enabling automatic drug infusion at precise 12-h intervals. The actuation principle relies on the sophisticated design of the device, where the rotational movement of the hour axis is converted into potential mechanical energy and is abruptly released at the exact moment for drug administration. The clock movement can be charged either automatically by mechanical agitations or manually by winding the crown, while the device remains implanted, thereby enabling the device to be used permanently without the need for batteries. When tested using metoprolol, an antihypertensive drug, in a spontaneously hypertensive animal model, the implanted device can deliver drug automatically at precise 12-h intervals without the need for further attention, leading to similarly effective blood pressure control and ultimately, prevention of ventricular hypertrophy as compared with scheduled drug administrations. These findings suggest that our device is a promising alternative to conventional methods for complex drug administration. [ABSTRACT FROM AUTHOR]

Self-injectable therapy has several advantages in the treatment of metabolic disorders. However, frequent injections with needles impair patient compliance and medication adherence. Therefore, we develop a fully implantable device capable of on-demand administration of self-injection drugs via noninvasive manual button clicks on the outer skin. The device is designed to infuse the drug only at the moment of click actuation, which allows for an accurate and reproducible drug infusion, and also prevents unwanted drug leakage. Using a mechanical means of drug infusion, this implantable device does not contain any electronic compartments or batteries, making it compact, and semi-permanent. When tested in animals, the device can achieve subcutaneous injection-like pharmacokinetic and pharmacodynamic effects for self-injection drugs such as exenatide, insulin, and glucagon. [ABSTRACT FROM AUTHOR]

For the prolonged, controlled delivery of systemic drugs, we propose an implantable drug-delivery chip (DDC) embedded with pairs of a microchannel and drug-reservoir serving as a drug diffusion barrier and depot, respectively. We pursued a DDC for dual drugs: a main-purpose drug, diclofenac (DF), for systemic exposure, and an antifibrotic drug, tranilast (TR), for local delivery. Thus, the problematic fibrotic tissue formation around the implanted device could be diminished, thereby less hindrance in systemic exposure of DF released from the DDC. First, we separately prepared DDCs for DF or TR delivery, and sought to find a proper microchannel length for a rapid onset and sustained pattern of drug release, as well as the required drug dose. Then, two distinct DDCs for DF and TR delivery, respectively, were assembled to produce a Dual_DDC for the concurrent delivery of DF and TR. When the Dual_DDC was implanted in living rats, the DF concentration in blood plasma did not drop significantly in the later periods after implantation relative to that in the early periods before fibrotic tissue formation. When the Dual_DDC was implanted without TR, there was a significant decrease in the blood plasma DF concentration as the time elapsed after implantation. Biopsied tissues around the Dual_DDC exhibited a significant decrease in the fibrotic capsule thickness and collagen density relative to the Dual_DDC without TR, owing to the effect of the local, sustained release of the TR. [ABSTRACT FROM AUTHOR]