Mobility and current boosting of In-Ga-Zn-O thin-film transistors with metal capping layer oxidation.

This study investigates the effect of an oxidized Ta capping layer on the boosting of field-effect mobility (µFE) of amorphous In-Ga-Zn-O (a-IGZO) Thin-film transistors (TFTs). The oxidation of Ta creates additional oxygen vacancies on the a-IGZO channel surface, leading to increased carrier density. We investigate the effect of increasing Ta coverage on threshold voltage (Vth), on-state current,µFEand gate bias stress stability of a-IGZO TFTs. A significant increase inµFEof over 8 fold, from 16 cm2Vs-1to 140 cm2Vs-1, was demonstrated with the Ta capping layer covering 90% of the channel surface. By partial leaving the a-IGZO uncovered at the contact region, a potential barrier region was created, maintaining the low off-state current and keeping the threshold voltage near 0 V, while the capped region operated as a carrier-boosted region, enhancing channel conduction. The results reported in this study present a novel methodology for realizing high-performance oxide semiconductor devices. The demonstrated approach holds promise for a wide range of next-generation device applications, offering new avenues for advancement in metal oxide semiconductor TFTs.

Improved high voltage operation of amorphous In-Ga-Zn-O thin film transistor by carrier density enhancement.

We report on improved high voltage operation of amorphous-In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) by increasing carrier density and distributing the high bias field over the length of the device which utilizes an off-set drain structure. By decreasing the O2partial pressure during sputter deposition of IGZO, the channel carrier density of the high voltage a-IGZO TFT (HiVIT) was increased to ∼1018cm-3. Which reduced channel resistance and therefore the voltage drop in the ungated offset region during the on-state. To further decrease the electric field in the offset region, we applied Ta capping and subsequent oxidation to locally increase the oxygen vacancy levels in the offset region thereby increasing local carrier density. The reduction of the drain field in the offset region from 1.90 Vµm-1to 1.46 Vµm-1at 200 V drain voltage, significantly improved the operational stability of the device by reducing high field degradation. At an extreme drain voltage of 500 V, the device showed an off-state current of ∼10-11A and on-state current of ∼1.59 mA demonstrating that with further enhancements the HiVIT may be applicable to thin-film form, low leakage, high voltage control applications.

An Ultralow Power Mixed Dimensional Heterojunction Transistor Based on the Charge Plasma pn Junction.

Development of a reliable doping method for 2D materials is a key issue to adopt the materials in the future microelectronic circuits and to replace the silicon, keeping the Moore's law toward the sub-10 nm channel length. Especially hole doping is highly required, because most of the transition metal dichalcogenides (TMDC) among the 2D materials are electron-doped by sulfur vacancies in their atomic structures. Here, hole doping of a TMDC, tungsten disulfide (WS2 ) using the silicon substrate as the dopant medium is demonstrated. An ultralow-power current sourcing transistor or a gated WS2 pn diode is fabricated based on a charge plasma pn heterojunction formed between the WS2 thin-film and heavily doped bulk silicon. An ultralow switchable output current down to 0.01 nA µm-1 , an off-state current of ≈1 × 10-14 A µm-1 , a static power consumption range of 1 fW µm-1 -1 pW µm-1 , and an output current ratio of 103 at 0.1 V supply voltage are achieved. The charge plasma heterojunction allows a stable (less than 3% variation) output current regardless of the gate voltage once it is turned on.

Microelectronic current-sourcing device based on band-to-band tunneling current.

A new stable current-sourcing transistor is developed using the band-to-band tunneling phenomenon. A heterojunction between thin film WS2and heavily hole-doped bulk silicon converts a section of the WS2contacting the silicon into a hole-doped WS2inside the WS2channel, and band-to-band tunneling occurs between the electron-doped and hole-doped WS2. The output current is regulated by the tunneling barrier thickness. The thickness depends on the gate bias for device switching, but is less sensitive to the source bias, enabling stable output currents. The minimum line sensitivity is 2.6%, and the temperature coefficient is 1.4 × 103ppm°C-1. The device can be operated as a current sourcing device with an ultralow output current and power consumption.

Tactile Interaction Sensor with Millimeter Sensing Acuity.

In this article we report on a 3 × 3 mm tactile interaction sensor that is able to simultaneously detect pressure level, pressure distribution, and shear force direction. The sensor consists of multiple mechanical switches under a conducting diaphragm. An external stimulus is measured by the deflection of the diaphragm and the arrangement of mechanical switches, resulting in low noise, high reliability, and high uniformity. Our sensor is able to detect tactile forces as small as ~50 mgf along with the direction of the shear force. It also distinguishes whether there is a normal pressure during slip motion. We also succeed in detecting the contact shape and the contact motion, demonstrating potential applications in robotics and remote input interfaces. Since our sensor has a simple structure and its function depends only on sensor dimensions, not on an active sensing material, in comparison with previous tactile sensors, our sensor shows high uniformity and reliability for an array-type integration.

Racial/ethnic differences in correlates of psychological distress among five Asian-American subgroups and non-Hispanic Whites.

Objective: Despite their vastly different historical backgrounds, unique languages and variable pre- and post-immigration experiences, Asian-Americans are considered to share stressors surrounding immigration, but there is a gap in describing manifestations of possible mental distress. Thus, the purpose of this study was to explore and compare differences in factors associated with psychological distress among Asian subgroups including Chinese, Filipino, Vietnamese, Korean, Japanese, and non-Hispanic Whites. Design: Using a cross-sectional study design, California Health Interview Survey (CHIS) 2011/2012 data were analyzed. The sample consisted of 29,142 participants: 25,645 non-Hispanic Whites, 3497 non-Hispanic Asian-Americans, 1156 Chinese, 471 Filipinos, 864 Vietnamese, 704 Koreans, and 302 Japanese. Sociodemographic characteristics included gender, age group, marital status, education, poverty level, working status, health insurance, level of acculturation, social cohesion, neighborhood safety, and civic engagement. Physical health status included disability and chronic illness. Psychological distress was evaluated using the Kessler 6 (K6) scale. Results: Results showed that psychological distress levels ranged between 1.96 and 4.52 (p < .05) out of 24 and associated factors were significantly different among the five Asian subgroups and non-Hispanic Whites. Conclusions: The current study highlights the differences in characteristics of psychological distress among Asian subgroups. It underscores the significance of understanding individualized cultural and historical background in each Asian subgroup and subsequently developing and applying appropriate interventions for those groups. In addition, different influencing factors should be applied to assess and prioritize the needs of Asian subgroups to improve psychological distress. The study also warrants further investigation and careful description of each Asian subgroups.

Buckled carbon nanotube network thin-film fabricated using chemically swelled elastomer substrates.

We report on the fabrication of buckled carbon nanotube thin-film networks (CNTN) that increases in conductivity with applied tactile pressure. When tactile pressure was applied, the buckled nanotubes collapsed and increased in interconnected density and as a result increased the thin-film conductivity. Unlike conventional methods using mechanically expanded elastomers, we utilize chemically swollen elastomers as the expanded substrate to transfer the CNTN. As the chemical evaporates, it compresses the CNTN causing the thin-film to buckle. The CNTN compression can be controlled by using organic solvents with differing elastomer absorption rates. Our method requires no mechanical instruments and shows in-plane multi-axial uniform strain for the entire substrate surface. Since the buckling was controlled chemically, the buckled CNTN can be produced reliably, furthering the possibility of its application as the active sensing material for highly sensitive tactile pressure sensors.

Graphene surface contacts of tin disulfide transistors for switching performance improvement and contact resistance reduction.

We investigated the performance improvement of tin disulfide channel transistors by graphene contact configurations. From its two-dimensional nature, graphene can make electric contacts only at the outermost layers of the channel. For intralayer current flow, two graphene flakes are contacted at the channel's top or bottom layer. For interlayer current flow, one flake is contacted at the top and bottom of each layer. We compared the transistor performance in terms of current magnitude, mobility, and subthreshold swing between the configurations. From such observations, we deduced that device characteristics depend on resistivity or doping level of individual graphene flakes. We also found that interlayer flow excels in the on-current magnitude and the mobility, and that top-contact configuration excels in the subthreshold swing.

Highly Sensitive Tactile Shear Sensor Using Spatially Digitized Contact Electrodes.

In this article, we report on a highly sensitive tactile shear sensor that was able to detect minute levels of shear and surface slip. The sensor consists of a suspended elastomer diaphragm with a top ridge structure, a graphene layer underneath, and a bottom substrate with multiple spatially digitized contact electrodes. When shear is applied to the top ridge structure, it creates torque and deflects the elastomer downwards. Then, the graphene electrode makes contact with the bottom spatially digitized electrodes completing a circuit producing output currents depending on the number of electrodes making contact. The tactile shear sensor was able to detect shear forces as small as 6 µN, detect shear direction, and also distinguish surface friction and roughness differences of shearing objects. We also succeeded in detecting the contact slip motion of a single thread demonstrating possible applications in future robotic fingers and remote surgical tools.

Racial and Ethnic Differences in Mental Health among Asian Americans and Non-Hispanic Whites: Based on California Health Interview Survey.

While Asians are becoming the largest ethnic group in the United States, studies have focused on Asians as a single population. The purpose of this study was to explore the racial and ethnic mental health differences between non-Hispanic Whites and Asians, with an emphasis on understudied subgroups, from the California Health Interview Survey 2011/2012. In this dataset Asians had significantly lower adjusted odds ratios for both mental distress and serious mental illness. However, when Asians were divided into subgroups and compared to Whites, Vietnamese and Japanese subgroups were significantly lower than Whites for mental distress while Koreans were significantly higher. Vietnamese and Chinese were found to have significantly less serious mental illness than Whites in the subgroup analyses. Our results underscore the importance of recognizing that Asian subgroups should not be overlooked, and all Asians should not automatically be treated as a homogenous group.

Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations.

The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

Simultaneous Detection of Displacement, Rotation Angle, and Contact Pressure Using Sandpaper Molded Elastomer Based Triple Electrode Sensor.

In this article, we report on a flexible sensor based on a sandpaper molded elastomer that simultaneously detects planar displacement, rotation angle, and vertical contact pressure. When displacement, rotation, and contact pressure are applied, the contact area between the translating top elastomer electrode and the stationary three bottom electrodes change characteristically depending on the movement, making it possible to distinguish between them. The sandpaper molded undulating surface of the elastomer reduces friction at the contact allowing the sensor not to affect the movement during measurement. The sensor showed a 0.25 mm −1 displacement sensitivity with a ±33 μm accuracy, a 0.027 degree −1 of rotation sensitivity with ~0.95 degree accuracy, and a 4.96 kP −1 of pressure sensitivity. For possible application to joint movement detection, we demonstrated that our sensor effectively detected the up-and-down motion of a human forefinger and the bending and straightening motion of a human arm.

A Portable Stiffness Measurement System.

A new stiffness measurement method is proposed that utilizes the lateral deformation profile of an object under indentation. The system consists of a force measurement module between a pair of equidistant touch sensing modules. Unique feature of the method is that by adjusting the touch module separation, indenter protrusion, and spring constant of the force sensing module, one can choose a desired sensing range for the force module. This feature helps to enhance the stiffness differentiation between objects of similar hardness and avoids measurement saturation. We devised a portable measurement system based on the method, and tested its performance with several materials including polymer foams and human skin.

Effects of Community-Based Health Worker Interventions to Improve Chronic Disease Management and Care Among Vulnerable Populations: A Systematic Review.

BACKGROUND: Community-based health workers (CBHWs) are frontline public health workers who are trusted members of the community they serve. Recently, considerable attention has been drawn to CBHWs in promoting healthy behaviors and health outcomes among vulnerable populations who often face health inequities. OBJECTIVES: We performed a systematic review to synthesize evidence concerning the types of CBHW interventions, the qualification and characteristics of CBHWs, and patient outcomes and cost-effectiveness of such interventions in vulnerable populations with chronic, noncommunicable conditions. SEARCH METHODS: We undertook 4 electronic database searches-PubMed, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and Cochrane-and hand searched reference collections to identify randomized controlled trials published in English before August 2014. SELECTION: We screened a total of 934 unique citations initially for titles and abstracts. Two reviewers then independently evaluated 166 full-text articles that were passed onto review processes. Sixty-one studies and 6 companion articles (e.g., cost-effectiveness analysis) met eligibility criteria for inclusion. DATA COLLECTION AND ANALYSIS: Four trained research assistants extracted data by using a standardized data extraction form developed by the authors. Subsequently, an independent research assistant reviewed extracted data to check accuracy. Discrepancies were resolved through discussions among the study team members. Each study was evaluated for its quality by 2 research assistants who extracted relevant study information. Interrater agreement rates ranged from 61% to 91% (average 86%). Any discrepancies in terms of quality rating were resolved through team discussions. MAIN RESULTS: All but 4 studies were conducted in the United States. The 2 most common areas for CBHW interventions were cancer prevention (n = 30) and cardiovascular disease risk reduction (n = 26). The roles assumed by CBHWs included health education (n = 48), counseling (n = 36), navigation assistance (n = 21), case management (n = 4), social services (n = 7), and social support (n = 18). Fifty-three studies provided information regarding CBHW training, yet CBHW competency evaluation (n = 9) and supervision procedures (n = 24) were largely underreported. The length and duration of CBHW training ranged from 4 hours to 240 hours with an average of 41.3 hours (median: 16.5 hours) in 24 studies that reported length of training. Eight studies reported the frequency of supervision, which ranged from weekly to monthly. There was a trend toward improvements in cancer prevention (n = 21) and cardiovascular risk reduction (n = 16). Eight articles documented cost analyses and found that integrating CBHWs into the health care delivery system was associated with cost-effective and sustainable care. CONCLUSIONS: Interventions by CBHWs appear to be effective when compared with alternatives and also cost-effective for certain health conditions, particularly when partnering with low-income, underserved, and racial and ethnic minority communities. Future research is warranted to fully incorporate CBHWs into the health care system to promote noncommunicable health outcomes among vulnerable populations.

Community Health Worker Perspectives on Recruitment and Retention of Recent Immigrant Women in a Randomized Clinical Trial.

This study explores the recruitment and retention strategies used by community health workers who enrolled Korean Americans in a church-based, randomized trial to promote mammogram and Papanicolaou tests and retained them for 6 months. We conducted 4 focus groups with 23 community health workers. Data were analyzed using a thematic analysis. Themes were identified in relation to recruitment: personal networks, formal networks at churches, building on trust and respect, and facilitating a nonthreatening environment. Themes were identified for retention: trust and peer support. Qualified, well-trained community health workers can recruit and retain hard-to-reach immigrant women in a randomized trial by using multiple culturally sensitive strategies.

Contact Pressure Level Indication Using Stepped Output Tactile Sensors.

In this article, we report on a novel diaphragm-type tactile pressure sensor that produces stepwise output currents depending on varying low contact pressures. When contact pressures are applied to the stepped output tactile sensor (SOTS), the sensor's suspended diaphragm makes contact with the substrate, which completes a circuit by connecting resistive current paths. Then the contact area, and therefore the number of current paths, would determine the stepped output current produced. This mechanism allows SOTS to have high signal-to-noise ratio (>20 dB) in the 3-500 Hz frequency range at contact pressures below 15 kPa. Moreover, since the sensor's operation does not depend on a material's pressure-dependent electrical properties, the SOTS is able to demonstrate high reproducibility and reliability. By forming a 4 × 4 array of SOTS with a surface bump structure, we demonstrated shear sensing as well as surface (1 × 1 cm²) pressure mapping capabilities.

Spatially digitized tactile pressure sensors with tunable sensitivity and sensing range.

When developing an electronic skin with touch sensation, an array of tactile pressure sensors with various ranges of pressure detection need to be integrated. This requires low noise, highly reliable sensors with tunable sensing characteristics. We demonstrate the operation of tactile pressure sensors that utilize the spatial distribution of contact electrodes to detect various ranges of tactile pressures. The device consists of a suspended elastomer diaphragm, with a carbon nanotube thin-film on the bottom, which makes contact with the electrodes on the substrate with applied pressure. The electrodes separated by set distances become connected in sequence with tactile pressure, enabling consecutive electrodes to produce a signal. Thus, the pressure is detected not by how much of a signal is produced but by which of the electrodes is registering an output. By modulating the diaphragm diameter, and suspension height, it was possible to tune the pressure sensitivity and sensing range. Also, adding a fingerprint ridge structure enabled the sensor to detect the periodicity of sub-millimeter grating patterns on a silicon wafer.

Sleep duration and quality in relation to non-alcoholic fatty liver disease in middle-aged workers and their spouses.

BACKGROUND & AIMS: Although accumulated evidence implies that short sleep duration and poor sleep quality may lead to an altered metabolic milieu, potentially triggering the development of non-alcoholic fatty liver disease (NAFLD), no studies have explored this association. This study sought to examine whether short sleep duration or poor sleep quality is associated with NAFLD in the general population. METHODS: We assessed sleep duration and quality using the Pittsburgh Sleep Quality Index in 69,463 middle-aged workers and their spouses and carried out biochemical and anthropometric measurements. The presence of fatty liver was determined using ultrasonographic findings. Logistic regression models were used to evaluate the association of sleep duration and quality with NAFLD, after adjusting for potential confounders. RESULTS: After controlling for the relevant confounding factors (age, alcohol intake, smoking, physical activity, systolic blood pressure, education level, marital status, presence of job, sleep apnea, and loud snoring), the adjusted odds ratio (95% confidence interval) for NAFLD comparing sleep duration ≤5 h to the reference (>7h) was 1.28 (1.13-1.44) in men and 1.71 (1.38-2.13) in women. After further adjustments for BMI, this association was not significant in men (OR: 1.03, 95% CI: 0.90-1.19) but remained significant in women (OR: 1.59, 95% CI: 1.23-2.05). The multivariate-adjusted odds ratio comparing participants with poor sleep quality vs. participants with good sleep quality was 1.10 (95% CI 1.02-1.19) and 1.36 (95% CI 1.17-1.59) in men and women, respectively. CONCLUSIONS: In the middle-aged, general population, short sleep duration, and poor sleep quality were significantly associated with an increased risk of NAFLD. Prospective studies are required to confirm this association.

Spray-coated carbon nanotube thin-film transistors with striped transport channels.

We present results for the transfer characteristics of carbon nanotube thin-film transistors (CNT-TFTs) that utilize single-walled carbon nanotube thin-films prepared by direct spray-coating on the substrate. By varying the number of spray-coatings (N(sp)) and the concentration of nanotubes in solution (C(NT)), it was possible to control the conductivity of the spray-coated nanotube thin-film from 129 to 0.1 kΩ/□. Also, by introducing stripes into the channel of the CNT-TFT, and thereby reducing the number of metallic percolation paths between source and drain, it was possible to enhance the on/off current ratio 1000-fold, from 10 to 10(4), demonstrating that it may be possible to utilize spray-coating as a method to fabricate CNT-TFTs for large area switching array applications.

Trends in Nursing Research on Life-Sustaining Treatment in South Korea after the Enforcement of the Act on Decisions on Life-Sustaining Treatment.

Purpose: This study investigated trends of nursing research on life-sustaining treatment in South Korea. Methods: The period for data search was set from January 2018 to December 2020. The major search terms used were advance directives and life-sustaining treatment. Of the 492 records identified in the initial search, 461 articles were excluded for various reasons. A total of 31 records were included in the final qualitative analysis. Results: Sixteen studies had nursing students as study subjects, while nine studies had nurses as study subjects. The majority of the studies employed cross-sectional descriptive surveys as their research design. The major themes that emerged from the studies were as follows attitudes toward withdrawal of life-sustaining treatment, knowledge of and attitudes toward advance directives, perceptions of a good death, and nurses' attitude toward life support care. Most of the studies reviewed concluded that attitudes toward withdrawal of life-sustaining treatment significantly impacted both knowledge of and attitudes toward advance directives and perceptions of a good death. Conclusion: To date, Korea still lacks extensive nursing research concerning life support care. Further research is needed to provide systematic education for nursing ethics and life support care, as well as the introduction of a specialist course. Furthermore, a multidisciplinary approach is necessary to provide diverse support systems and policy measures. In particular, since nurses are directly responsible for providing life support care, nurses' roles should be expanded in accordance with the Act on Decisions on Life-Sustaining Treatment.