Finger Width Research Articles

Effective diffusion along the backbone of combs with finite-span 1D and 2D fingers.

Diffusion in complex heterogeneous media, such as biological tissues or porous materials, typically involves constrained displacements in tortuous structures and sticky environments. Therefore, diffusing particles experience both entropic (excluded-volume) forces and the presence of complex energy landscapes. In this situation, one may describe transport through an effective diffusion coefficient. In this paper, we examine comb structures with finite-length 1D and finite-area 2D fingers, which act as purely diffusive traps. We find that there exists a critical width of 2D fingers, above which the effective diffusion along the backbone is faster than for an equivalent arrangement of 1D fingers. Moreover, we show that the effective diffusion coefficient is described by a general analytical form for both 1D and 2D fingers, provided the correct scaling variable is identified as a function of the structural parameters. Interestingly, this formula corresponds to the well-known general situation of diffusion in a medium with fast reversible adsorption. Finally, we show that the same formula describes diffusion in the presence of dilute potential energy traps, e.g., through a landscape of square wells. While diffusion is ultimately always the result of microscopic interactions (with particles in the fluid, other solutes, and the environment), effective representations are often of great practical use. The results reported in this paper help clarify the microscopic origins and the applicability of global, integrated descriptions of diffusion in complex media.

Dual Leap Motion Controller 2: A Robust Dataset for Multi-view Hand Pose Recognition

This paper presents Multi-view Leap2 Hand Pose Dataset (ML2HP Dataset), a new dataset for hand pose recognition, captured using a multi-view recording setup with two Leap Motion Controller 2 devices. This dataset encompasses a diverse range of hand poses, recorded from different angles to ensure comprehensive coverage. The dataset includes real images with the associated precise and automatic hand properties, such as landmark coordinates, velocities, orientations, and finger widths. This dataset has been meticulously designed and curated to maintain a balance in terms of subjects, hand poses, and the usage of right or left hand, ensuring fairness and parity. The content includes 714,000 instances from 21 subjects of 17 different hand poses (including real images and 247 associated hand properties). The multi-view setup is necessary to mitigate hand occlusion phenomena, ensuring continuous tracking and pose estimation required in real human-computer interaction applications. This dataset contributes to advancing the field of multimodal hand pose recognition by providing a valuable resource for developing advanced artificial intelligence human computer interfaces.

A Micromachined Silicon-on-Glass Accelerometer with an Optimized Comb Finger Gap Arrangement.

This paper reports the design, fabrication, and characterization of a MEMS capacitive accelerometer with an asymmetrical comb finger arrangement. By optimizing the ratio of the gaps of a rotor finger to its two adjacent stator fingers, the sensitivity of the accelerometer is maximized for the same comb finger area. With the fingers' length, width, and depth at 120 μm, 4 μm, and 45 μm, respectively, the optimized finger gap ratio is 2.5. The area of the proof mass is 750 μm × 560 μm, which leads to a theoretical thermomechanical noise of 9 μg/√Hz. The accelerometer has been fabricated using a modified silicon-on-glass (SOG) process, in which a groove is pre-etched into the glass to hold the metal electrode. This SOG process greatly improves the silicon-to-glass bonding yield. The measurement results show that the resonant frequency of the accelerometer is about 2.05 kHz, the noise floor is 28 μg/√Hz, and the nonlinearity is less than 0.5%.

The Mcgregor Pedicled Groin Flap for Hand Skin Defects

The groin flap is a surgical method used to cover soft tissue defects in the hand and forearm, such as wounds, traumatic amputations, degloving injuries, burns, burn scar release, and tumor excision. It is effective in covering extensive and intricate defects, such as wounds, traumatic amputations, degloving injuries, burns, burn scar release, and tumor excision. The procedure involves a remote autoplasty supported by the vascular territory of the superficial iliac circumflex artery. The flap's boundaries are defined using the "2 fingers width" criterion, and the flap is raised from lateral to medial, transferring subcutaneous tissue while keeping it above the fascia. The flap is closed using drain suction, and the patient is allowed to walk on the 5th day after surgery. Effective preoperative planning is essential for preventing the creation of too big or too tiny flaps and ensuring the fabrication of appropriate tubing to avoid complications. The McGregor groin flap is a commonly used technique for hand deformity reconstruction due to its extended pedicle and quick execution. It is adaptable, repeatable, and can be performed by less-experienced surgeons without microsurgery expertise. The flap covers significant tissue loss with pliable tissue, making it suitable for joints. It can cover abnormalities on the back or palm, and can be used for early wrist and hand rehabilitation. However, it has drawbacks, such as shoulder stiffness in older patients, discomfort during the upper limb positioning, and the need for multiple phases. Despite these, the groin flap remains relevant in the age of microsurgery and can be improved with technical modifications.

IFN-γ and IL-10 Immunosensor with Vertically Aligned Carbon Nanotube Interdigitated Electrodes toward Pen-Side Cattle Paratuberculosis Monitoring.

Highly sensitive vertically aligned carbon nanotube arrays (VANTAs) interdigitated electrode (IDE) arrays are developed for electrochemical biosensing of two cytokines (i.e., interleukin-10 (IL-10) and interferon-gamma (IFN-γ)) that are useful for early detection Johne's disease (Bovine Paratuberculosis) in cattle. The high aspect ratio VANTA-IDEs (50-60µm in height) are grown through a chemical vapor deposition process from an iron (Fe) catalyst that is lithographically patterned on a silicon wafer with equal finger width and inter-finger spacing of 25µm. After functionalization with distinct antibodies the VANTA-IDEs are capable of selective detection of both IL-10 and IFN-γ within an actual biological matrix (i.e., diluted bovine implant supernatant) over concentration ranges of 0.1 to 30 pgmL-1 (limit of detection - LOD: 0.0911 pgmL-1) and 50-500 pgmL-1 (LOD: 24.17 pgmL-1), respectively with a response time of <35 min. Results demonstrate important initial steps for rapid, pen-side identification of cattle with stage-I Mycobacterium avium subspecies paratuberculosis infection before physical symptoms of Johne's disease are present. Such a rapid pen-side diagnostic test can be used on cattle at an auction or before they are introduced to a herd to ensure the larger population does not become infected with Johne's disease.

Planar Micro-Supercapacitors with High Power Density Screen-Printed by Aqueous Graphene Conductive Ink.

Simple and scalable production of micro-supercapacitors (MSCs) is crucial to address the energy requirements of miniature electronics. Although significant advancements have been achieved in fabricating MSCs through solution-based printing techniques, the realization of high-performance MSCs remains a challenge. In this paper, graphene-based MSCs with a high power density were prepared through screen printing of aqueous conductive inks with appropriate rheological properties. High electrical conductivity (2.04 × 104 S∙m-1) and low equivalent series resistance (46.7 Ω) benefiting from the dense conductive network consisting of the mesoporous structure formed by graphene with carbon black dispersed as linkers, as well as the narrow finger width and interspace (200 µm) originating from the excellent printability, prompted the fully printed MSCs to deliver high capacitance (9.15 mF∙cm-2), energy density (1.30 µWh∙cm-2) and ultrahigh power density (89.9 mW∙cm-2). Notably, the resulting MSCs can effectively operate at scan rates up to 200 V∙s-1, which surpasses conventional supercapacitors by two orders of magnitude. In addition, the MSCs demonstrate excellent cycling stability (91.6% capacity retention and ~100% Coulombic efficiency after 10,000 cycles) and extraordinary mechanical properties (92.2% capacity retention after 5000 bending cycles), indicating their broad application prospects in flexible wearable/portable electronic systems.

Roles of Interdigitated Electrode Geometry in Non-Faradaic Impedimetric Biosensors

In this work, we investigate the effect of interdigitated electrode fingers width and gap on the performance of biosensors. Two different configurations of interdigitated electrodes were utilized; one consists of 50 μm wide fingers with a gap of 50 μm, and the other consists of 100 μm wide fingers with a 100 μm gap. First, the active surface area of both interdigitated electrodes was investigated. Then, the surface electronic parameters were investigated using faradaic and non-faradaic electrochemical impedance spectroscopy modes. Both interdigitated electrodes were then functionalized with LDL-antibodies through a standard chemical functionalization route and were utilized for the detection of LDL-antigen of cholesterol. The biosensor with 50 μm width and gap demonstrated better sensitivity and limit of detection of 6.08 nF/log(ng/ml) and 40 pg ml−1, respectively. Biosensors with 100 μm finger width and gap sensitivity and detection limit are 5.16 nF/log(ng/ml) and 300 pg ml−1, respectively. The enhanced sensitivity and limit of detection for the first biosensor is due to the increased surface area, enhanced electric field, and less diffusion of ions onto the biosensor surface. The study reported here suggests room for improving the geometry of many interdigitated electrodes for enhanced non-faradaic biosensing performances.

Towards a cutting‐edge metallization process for silicon heterojunction solar cells with very low silver laydown

AbstractWithin this work, we investigate the potential to optimize the screen‐printed front side metallization of silicon heterojunction (SHJ) solar cells. Three iterative experiments are conducted to evaluate the impact of the utilized fine mesh screen configurations and grid layout adaption (finger pitch) for the front side metallization on silver laydown and electrical performance of the solar cells. With respect to the screen configuration, we compare the performance of a fine‐mesh knotless screen to a conventionally angled screen demonstrating an additional gain of Δη = +0.1%abs due to reduced shading losses. Additionally, a grid layout is improved by increasing the number of contact fingers from 120 to 156. Furthermore, the current possibility to push the fine‐line printing process for low‐temperature pastes to the limit is investigated by reducing the nominal finger width wn to 20, 18, and 15 μm. It is shown that even the smallest nominal width of wn = 15 μm can be printed with high quality, leading to an additional efficiency gain of Δη = +0.15%abs as well as a reduction of silver paste laydown by −5 mg. Finally, a batch of champion cells is fabricated by applying the findings of the previous experiments, which results in a maximum efficiency of ηmax = 23.2%. Compared to the reference group without optimization, this corresponds to a gain of Δη = +0.17%abs, which comes along with an additional decrease of the silver paste laydown by approximately −2 mg. This emphasizes the significance of consistent optimization of the screen‐printing process in terms of cell performance and resource utilization for SHJ solar cells.

Microwave humidity sensor based on shorted split ring resonator with interdigital capacitance and α-Al2O3 nanoflakes/chitosan sensitive film for respiration monitoring

A microwave relative humidity (RH) sensor based on shorted split ring resonator with interdigital capacitance (SSRR-IDC) as a test platform and α-Al2O3 nanoflakes/chitosan (CS) composite as sensitive film is proposed for the detection of human respiration. The SSRR-IDC was designed by optimizing the finger spacing and width of the IDC. Electromagnetic simulation of the designed SSRR-IDC confirms a strong electric field distribution and high dielectric sensitivity in the IDC region. The porous α-Al2O3 nanoflakes/CS composite was coated onto the IDC region of the SSRR to obtain a microwave humidity sensor. Abundant hydrophilic groups and large specific surface area of the α-Al2O3 nanoflakes/CS contribute to the adsorption of water molecules. The proposed microwave humidity sensor shows excellent sensitivity in wide RH range, especially at high humidity condition. The working principle and the sensitivity enhancement mechanism of the proposed microwave sensor were explained by combining a circuit model analysis and the dielectric property and surface microstructure changes of the sensitive materials. Furthermore, the microwave sensor also demonstrates short response/recover time and outstanding repeatability, long-term stability, temperature stability, and selectivity. Additionally, the prepared microwave humidity sensor successfully records respiratory data from different volunteers. Changes in respiratory depth before and after drinking water of the volunteers can also be distinguished by this sensor.

Impact of Gate Oxide Thickness on Flicker Noise (1/f) in PDSOI n-channel FETs

This work reports the impact of gate oxide thickness on flicker noise (1/f) in 45-nm RFSOI NFET devices. In addition, the effect of finger width scaling on 1/f noise parameters is studied in linear region. The dominant source of 1/f noise is also analyzed. It is observed that thin oxide devices show carrier number fluctuation; however, for thick oxide devices, correlated number-mobility govern the noise. Extracted trap densities using 1/f noise show higher volume trap densities in thin oxide devices. Moreover, trap distribution behavior is analyzed using frequency exponent. Further, GLOBALFOUNDRIES PDK is utilized to model 1/f noise behavior of the devices.

Design and simulation of capacitive sensor for grain moisture detection

The high moisture content of grain would result in quality deteriorations such as mold and mildew during storage and transportation. For effective detection of grain moisture, a forked-finger capacitive sensor in the form of triangular prism is proposed. The effect of the sensor structural parameters on its capacitance, electric field distribution, sensitivity and penetration depth are investigated using finite element simulations. The results show that an optimised effective penetration depth of 2.73 mm for grain moisture detection can be achieved when the finger width, number, length and spacing are 50 μm, 25.4 mm and 50 μm, respectively. This work may provide a new approach for the structural design of capacitive grain moisture sensors.

Vibration effect on Rayleigh–Taylor instability of sedimenting suspension

In this paper, the effect of vertical vibration on the Rayleigh–Taylor instability at the lower interface of a sedimenting suspension layer sandwiched between viscous fluids is studied numerically and theoretically. It is shown numerically that the vibration suppresses the amplitudes of interface perturbations and enlarges the widths of granular fingers, postponing the nonlinear growth stage. By modeling the suspension as a fluid with its effective density and viscosity, stability analyses are carried out, and the dominant growth rate and the dominant wave number predicted by the dispersion relation agree with the numerical results, especially for cases with strong vibrations. Because of the small-scale flow induced by the particles, high vibration acceleration amplitude and low vibration frequency, which correspond to a large vibration power input, increase the kinetic energy spectra at the high wave number regime, a phenomenon contrary to the vibration effect for pure fluid cases.

Disorder-induced non-linear growth of fingers in immiscible two-phase flow in porous media

Immiscible two-phase flow in porous media produces different types of patterns depending on the capillary number Ca and viscosity ratio M. At high Ca, viscous instability of the fluid–fluid interface occurs when the displaced fluid is the more viscous, and leads to viscous fingering, which is believed to exhibit the same growth behavior as the viscously-unstable fingers observed in Hele–Shaw cells by Saffman and Taylor [“The penetration of a fluid into a porous medium or Hele–Shaw cell containing a more viscous liquid,” Proc. R. Soc. London 245, 312 (1958)], or as diffusion-limited aggregates (DLA). In such Laplacian growth processes, the interface velocity depends linearly on the local gradient of the physical field that drives the growth process (for two-phase flow, the pressure field). However, a non-linear power-law dependence between the flow rate and the global pressure drop, reminiscent of what has also been observed for steady-state two-phase flow in porous media, was evidenced experimentally for the growth of viscously-unstable drainage fingers in two-dimensional porous media, 20 years ago. Here, we revisit this flow regime using dynamic pore-network modeling and explore the non-linearity in the growth properties. We characterize the previously unstudied dependencies of the statistical finger width and non-linear growth law's exponent on Ca, and discuss quantitatively, based on theoretical arguments, how disorder in the capillary barriers controls the growth process' non-linearity, and why the flow regime crosses over to Laplacian growth at sufficiently high Ca. In addition, the statistical properties of the fingering patterns are compared to those of Saffman–Taylor fingers, DLA growth patterns, and the results from the aforementioned previous experimental study.

Frequency of Diastasis Recti in Second and Third Trimesters of Pregnancy in Jinnah Hospital Lahore. A Cross-Sectional Study

Background: Diastasis Recti (DR) is a condition characterized by the separation of the rectus abdominis muscles, commonly occurring among pregnant women. Despite its prevalence, awareness of DR and its implications remains low. This study aims to investigate the frequency of DR in the second and third trimesters of pregnancy and to identify any associated risk factors. Objective: To determine the prevalence of DR among pregnant women in their second and third trimesters and to assess the level of awareness about the condition. Additionally, the study seeks to explore the relationship between DR and potential risk factors such as the number of pregnancies, Body Mass Index (BMI), and engagement in abdominal muscle exercises. Methods: This cross-sectional study was conducted at Jinnah Hospital Lahore, involving 64 pregnant women in their second and third trimesters. Participants were selected through non-probability convenience sampling. DR was assessed using the Finger width method, alongside a questionnaire to gather demographic information and assess awareness levels. Statistical analysis was performed using SPSS version 25, focusing on descriptive statistics to summarize demographic data, and chi-square tests to explore associations between DR and identified risk factors. Results: Among the 64 participants, DR was present in 45.3% (29/64) of the sample, with a higher prevalence observed in the third trimester. The majority of participants (90.6%) reported never performing abdominal muscle exercises. A systematic review indicated that antenatal exercises could reduce DR cases by approximately 35%. However, awareness of DR among participants was notably lacking, with none having prior knowledge of the condition. Additionally, there was no significant association between DR and BMI, or the frequency of abdominal exercises. Conclusion: DR is a prevalent condition among pregnant women, particularly in their third trimester, with a significant lack of awareness observed. While the number of pregnancies appears to be a contributing factor, other explored risk factors such as BMI and engagement in abdominal exercises did not show a significant association with DR. These findings highlight the need for increased educational efforts and further research to better understand and manage DR during pregnancy.

Air invasion into three-dimensional foam induces viscous fingering instabilities

We conducted an experimental investigation to examine the immiscible radial displacement flows of air invading three-dimensional foam in a Hele-Shaw cell. Our study successfully identified three distinct flow regimes. In the initial regime, characterized by relatively low fingertip velocities, the foam underwent a slow displacement through plug flow. During this process, the three-phase contact lines slipped at the cell walls. Notably, we discovered that the air injection pressure exhibited a proportional relationship with the power of the fingertip velocity. This relationship demonstrated excellent agreement with a power law, where the exponent was determined to be 2/3. Transitioning to the second regime, we observed relatively high velocities, resulting in the displacement of the foam as a plug within single layers of foam bubbles. The movement of these bubbles near the cell walls was notably slower. Similar to the first regime, the behavior in this regime also adhered to a power law. In the third regime, which manifested at higher air injection pressures, the development of air fingers occurred through narrow channels. These channels had the potential to isolate the air fingers as they underwent a process of "healing." Furthermore, our results unveiled a significant finding that the width of the air fingers exhibited a continuous scaling with the air injection pressure, irrespective of the flow regimes being observed.

(194) Midline Reservoir Placement of Infrapubic Inflatable Penile Prosthesis: A Step-by-Step Surgical Technique

Abstract Introduction Various alternative placements of inflatable penile prosthesis (IPP) reservoirs have been previously documented, differing from the traditional retroperitoneal placement in the Space of Retzius. Pelvic trauma, history of surgery in the pelvic region, and atypical anatomy can necessitate an alternative location for implantation of the IPP reservoir. The midline placement of the IPP reservoir provides numerous advantages in outcomes, patient experience, and versatility of implantation. This video demonstrates the surgical procedure for midline placement of the IPP reservoir. Objective We outline a surgical technique to place the IPP reservoir in an alternative midline location. Methods The patient was instructed to void his bladder prior to the procedure to circumvent Foley catheter insertion. A 2.5 cm-wide horizontal incision was made 2 finger widths cranially to the dorsal aspect of the base of the penis. The surgeon’s index finger was used for blunt dissection along the linea alba above the pubic tubercles. A tonsil clamp is used to pierce the rectus fascia at the midline, below the arcuate line, to leave a defect just wide enough to accommodate a 70 mm nasal speculum. The surgeon’s finger is used to assess the space to determine if a 9/10 mm Hegar dilator is necessary to expand the avascular space by sweeping it parallel to the fascia. The speculum is inserted and positioned with the blades pointed cranially parallel to the facial axis and the handles pointed superiorly. The reservoir is prepared and delivered into this space using a metal pediatric Yankauer suction tip through the open blades of the nasal speculum. A syringe filled with saline solution is connected to the reservoir tubing, and the fluid is transferred completely to the reservoir and the tubing is clamped. The tubes originating from the reservoir and implant cylinders are both clamped, trimmed to length, and connected to each other in a watertight fashion to permit the bidirectional flow of saline solution. Proper IPP cylinder inflation is tested prior to closing the incision. Results The reservoir is thus safely deployed cranially to the pubic bone and avoids interfering with the urinary bladder. No complications were observed in this patient, and he was discharged on the same day. Conclusions The midline surgical placement of the reservoir during the infrapubic implantation of an inflatable penile prosthesis is a safe and effective alternative placement for patients with prior pelvic surgery, injuries, or atypical pelvic anatomy. Patients with compromised pelvic, abdominal, or inguinal regions due to hernia repair, patulous inguinal rings, or dense lateral pelvic scarring stand to benefit the most from this reservoir placement. This procedure outlines the surgical steps of midline reservoir placement for new IPP implantation or relocation during a revision procedure. Disclosure No.

A Systematic Review on the Current Attitudes and Clinical Practices on the Use of Cuffed and Uncuffed Endotracheal Tubes in Pediatric Anesthesia.

For several decades now, the use of uncuffed endotracheal tube (ETT) is the gold standard in providing airway and ventilatory support to children under anesthesia. However, there has been a change in focus from the application of uncuffed ETT to cuffed ETT among children, and this matter has been debated for years. In fact, several studies have shown that even across and within countries, the attitudes and practices of anesthesiologists on the use of types of endotracheal tubes differed. To describe the current attitudes and practices of anesthesiologists regarding the use of uncuffed or cuffed ETT for children. A systematic review of observational studies on the current attitudes and practices of pediatric anesthesiologists regarding the use of cuffed and uncuffed ETT was conducted from May to November 2020. Cochrane reviews, Medline, Pubmed, and EMBASE were searched and yielded five relevant studies. The use of cuffed ETT ranged between 11%-61% in the included studies and all reported that there were no consensus or standard on whether cuffed or uncuffed ETT was better. Reported factors for cuffed ETT use included: 1) Personal choice, 2) Department protocol, 3) Availability of resources, and 4) Specific conditions such as obesity, planned or emergency procedure, and reduced lung compliance. In terms of ETT size, reported criteria were: 1) Use of a formula, 2) Use of abacus/calculator, and 3) In relation to the fifth finger's width. The current systematic review demonstrated that there is wide variation in current attitudes and practices of anesthesiologists regarding the use of uncuffed or cuffed endotracheal tubes in children. Likewise, factors affecting choice of ETT and criteria for selection varied in the published literature. The results of this systematic review highlight the need for a standard guideline to help clinicians choose if cuffed or uncuffed ETT is better in certain scenarios and to help them decide in selecting the most appropriate ETT size.

Siravedha - A Case Report on the Ayurvedic Treatment of Vatakantaka w.s.r. to Plantar Fasciitis

Vatakantaka is a very common complaint now days with mild to severe pain in the Pada (foot), Parshini (heel), Gulfa (ankle), Jangha (calf) of the patient. Contemporary medicine describes this condition as Plantar fasciitis which presents as pain in the plantar aspect of the foot frequently associated with heel and ankle pain. It usually does not respond to standard pain management medications, techniques and is a major cause of embarrassment and disability for the patient. This case report refers to the complete remission of Vatakantaka (plantar fasciitis) in a 49 year old female patient with the use of Siravedha (venesection/bloodletting) of the Sira (vein) located 2 Angul (finger width) above Padagata Kshipra Marma (vital point in foot). A total of 3 sittings of Siravedha were done with a gap of 9 days between consecutive sittings. The 1st sitting itself relieved the pain significantly with complete relief from pain and tenderness after all the three sittings were completed. The 3 month long follow up revealed that the symptoms did not reoccur. This case report serves as an example that classical Ayurvedic methods for pain relief such as Siravedha can be explored for improving the management protocols for diseases like Vatakantaka (plantar fasciitis). Further large sample studies are needed to confirm the findings.

Impact of Parasitic Gate Capacitance on RF Performance in GaN-Based HEMTs for X-Band Applications

GaN-based high-electron-mobility transistors (HEMTs) are intensively researched for high-power radio frequency (RF), low noise, and aerospace applications, thanks to their high breakdown electric field, high carrier mobility and density at the hetero-interface, and wide bandgap [1-2]. For the improvement of RF performance, various approaches have been reported, including T-gate structure [3-4], surface passivation [5], n+-regrown source and drain contact [6], thin barrier structure [7], and graded-channel [8]. Among them, the T-gate structure has been extensively employed for the reduction of the gate resistance (Rg ) and thereby improvement of the RF performance. However, the usage of the wide T-gate structure enlarges parasitic gate capacitance components, which deteriorates the RF performance. As a result, one should pay careful attention to the dimension of the wide T-gate structure to reduce Rg as much as possible, not to enlarge the parasitic gate capacitance components. This motivates us to explore the optimum dimension of the wide T-gate structure in GaN-based HEMTs for X-band RF applications.To investigate the detailed impact of the gate resistance and parasitic gate capacitance components, we fabricated LG = 0.15 μm GaN-based HEMTs with various dimensions of the T-gate head from 0.5 to 0.8 μm during an e-beam lithography process step. The unit gate width (WG ) and number of gate finger (NF ) were 100 μm and 2, respectively.For comparison of the device characteristics with respect to the dimension of the gate head, DC and RF measurements were conducted for the fabricated GaN-based HEMTs with various dimensions of T-gate head. The DC characteristics in terms of the threshold voltage (VTH ), the maximum transconductance (gm,max ), and the saturation drain current (Id,sat ) were almost identical, regardless of the dimension of the T-gate head. On the contrary, the current-gain cut-off frequency (fT ) and maximum oscillation frequency (fMAX ) were improved by 26.5% and 21.0%, respectively, when the T-gate head size was reduced from 0.8 to 0.5 μm.In an effort of explore the origin of the dependence of the T-gate head on the RF performance, we have carried out small-signal modeling to extract the parasitic gate capacitance and gate resistance components from the measured RF data. As the T-gate head size was reduced from 0.8 to 0.5 μm, the gate-source parasitic capacitance component (Cgs_par ) was reduced by 19%, while the gate resistance component was increased by 32%. In our device design and fabrication, it turned out that the reduction of Cgs_par was more beneficial than the increase of Rg , leading to the improved RF performance with the gate head size decrease.In this work, our systematic research revealed that, unlike earlier reports [3-4], the reduction of the parasitic gate capacitance was essential for the improvement of the RF performance as opposed to the reduction of the gate resistance in LG = 0.15 μm GaN-based HEMTs for X-band RF applications. Acknowledgement This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (No. NRF-2021M3C1C3097672).

3D Printed Stamps for Transfer Printing of Flexible and Wearable Supercapacitors

In recent times, there has been an increasing demand for portable, lightweight, and flexible electronic devices. These electronic devices are required in healthcare, robotics, sports, defence, and other applications. Energy storage unit is one of the key requirements of these electronics and solid-state micro-supercapacitors (MSCs) are preferred for flexible and wearable electronics.[1,2] However, conventional methods of manufacturing MSCs are complex, time-consuming, and costly. This work aims to explore an alternative approach to developing MSCs by transferring electronic inks onto paper, textiles, and other flexible substrates using 3D-printed stamps. Different in-plane MSCs with varying finger widths and interspace gaps were fabricated to find the optimum electrochemical properties. The developed devices exhibit excellent electrochemical performance including high power density, high energy density, excellent lifetime, and excellent flexibility under different mechanical deformation conditions (such as bending, rolling, folding, etc.). This approach has a huge potential for fabrication of next-generation electronics for flexible and wearable electronic applications.