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Objective: To evaluate the risks of developing gestational diabetes (GDM) and pregnancy-induced hypertension (PIH) in women with polycystic ovary syndrome (PCOS) using data from Korea’s National Health Insurance Service. Method: The PCOS group comprised women aged 20 to 49 years diagnosed with PCOS between 1 January 2012, and 31 December 2020. The control group comprised women aged 20 to 49 years who visited medical institutions for health checkups during the same period. Women with any cancer within 180 days of the inclusion day were excluded from both the PCOS and control groups, as were women without a delivery record within 180 days after the inclusion day, as well as women who visited a medical institution more than once before the inclusion day due to hypertension, diabetes mellitus (DM), hyperlipidemia, DM in pregnancy, or PIH. GDM and PIH were defined as cases with at least three visits to a medical institution with a GDM diagnostic code and a PIH diagnostic code, respectively. Results: Overall, 27,687 and 45,594 women with and without a history of PCOS experienced childbirth during the study period. GDM and PIH cases were significantly higher in the PCOS group than in the control group. When adjusted for age, SES, region, CCI, parity, multiple pregnancies, adnexal surgery, uterine leiomyoma, endometriosis, PIH, and GDM, an increased risk of GDM (OR = 1.719, 95% CI = 1.616–1.828) was observed among women with a history of PCOS. There was no increase in the risk of PIH among women with a history of PCOS (OR = 1.243, 95% CI = 0.940–1.644). Conclusion: A history of PCOS itself might increase the risk of GDM, but its relationship with PIH remains unclear. These findings would be helpful in the prenatal counseling and management of patients with PCOS-related pregnancy outcomes.

Background Thisretrospective cohort study analyzed the risk of gastrointestinal (GI) cancer in patients who underwent hysterectomy due to a benign gynecologic disease in comparison with the no hysterectomy group using Korean health insurance data. Methods This population-based retrospective cohort study was conducted using insurance data provided by the Health Insurance Review and Assessment Service (HIRA) from January 1, 2007, to December 31, 2020. The hysterectomy group included 40- to 59-year-old women who underwent hysterectomy with uterine leiomyoma or uterine endometriosis from January 1, 2011, to December 31, 2014. The control group included women aged 40 to 59 years who visited medical institutions for medical examination from January 1, 2011 to December 31, 2014. Results The hysterectomy and no hysterectomy groups comprised 66,204 and 89,768 subjects, respectively. The median ages in the no hysterectomy group and hysterectomy group were 48 (range: 43–53) and 46 (range: 44–49) years, respectively. In the unadjusted results of the analysis, all colorectal cancer (CRC) increased in the hysterectomy alone group (HR 1.222, 95% confidence interval (CI) 1.016-1.47, p = 0.033), sigmoid colon cancer increased in the hysterectomy alone group (HR 1.71, 95% CI 1.073-2.724, p = 0.024), and rectal cancer increased in the hysterectomy with adnexal surgery group (HR 1.924, 95% CI 1.073-2.724, p = 0.002). The adjusted results showed that all CRC increased in the hysterectomy alone group (HR 1.406, 95% CI 1.057-1.871, p = 0.019), colon cancer increased in the hysterectomy alone group (HR 1.523, 95% CI 1.068-2.17, p = 0.02), and rectal cancer increased in the hysterectomy with adnexal surgery group (HR 1.933, 95% CI 1.131-3.302, p = 0.016). The all-cause mortality of GI cancer increased in the hysterectomy alone group (HR 3.495, 95% CI 1.347-9.07, p = 0.001). Conclusions This study showed that the risk of all CRC increased in women who underwent hysterectomy compared with women who did not. In particular, the risk of rectal cancer was significantly higher in the women who underwent hysterectomy with adnexal surgery than in the controls.

There is an ever-increasing demand for polymer-based electrical leads patterned on polymer substrates of any shape to connect two electrical components. Much, however, still remains challenging about electrical leads made of polymer nanocomposites that have high affinity to polymer substrates and outstanding applicability to curved surfaces, unlike metals. This leads to the need for development of photopatternable and electrically conductive polymer nanocomposites and, by extension, comprehensive understanding of the constituent and processes involved in their development. Here, a set of polymer nanocomposites incorporating exfoliated graphite nanoplatelet (xGnP) into SU-8, xGnP/SU-8 nanocomposites, are developed as photopatternable and electrically conductive nanocomposites for electrical lead micropatterning. The inclusion of xGnP, carbon-based conductive nanofiller, is intended to provide electrical conductivity and the use of SU-8, photocurable host polymer, is designed to achieve both patternability and strong adhesion to polymer surfaces. First, the patterning characteristics of xGnP/SU-8 nanocomposites are explored with regard to patterning thickness and patterning error; The dependence of patterning characteristics on xGnP content and UV exposure dose are extensively investigated. Next, we explore an evolution in the electrical conductivity of xGnP/SU-8 nanocomposites with variation of xGnP content to understand their electrical behavior. Finally yet importantly, the applicability of xGnP/SU-8 nanocomposites to electrical lead micropatterning is demonstrated by photopatterning an electrical circuit for light emitting diode (LED) chips using the xGnP/SU-8 nanocomposites on polydimethylsiloxane (PDMS) substrate. The findings of this study will contribute to a significant growth of polymer-based electrical leads and better understanding of photopatternable and electrically conductive nanocomposites.

This study evaluates the relationship between menopausal hormone therapy (MHT) and the risk of urologic cancer in women. It was conducted for South Korea’s national population based on the National Health Insurance Service Database between January 2002 and January 2019. The types of MHT in this study included tibolone, combined oestrogen plus progestin by the manufacturer (CEPM) or physician (CEPP), and oral and topical oestrogen. Furthermore, select patient characteristics and reproductive factors were reviewed. We performed a Cox proportional hazard analysis to clarify the risk of urologic cancer associated with MHT. According to MHT types, 104,089 were treated with tibolone, 65,597 with CEPM, 29,357 with oral oestrogen, 3,913 with CEPP, and 1,174 with topical oestrogen. Among women on MHT, the incidence of kidney cancer was significantly increased with oral oestrogen (hazard ratio [HR] 1.36, 95% confidence interval [CI]: 1.062–1.735) and topical oestrogen (HR 2.84, 95% CI: 1.270–6.344), whereas other formulations were not associated with kidney cancer. Meanwhile, tibolone significantly decreased the incidence of bladder cancer (HR 0.69, 95% CI: 0.548–0.858), whereas other formulations were not associated with bladder cancer. Our findings suggest that MHT in postmenopausal women affects the incidence of urologic cancers.

A vortex tube is a simple device that separates incoming gas into cold and hot gases. Several theories have been proposed to explain the principle of energy separation in the vortex tube. Existing theories have advantages and defects. Recently, various studies employed numerical simulations to study the flow in the vortex tube. As a result, flow structures were well clarified. However, in most cases, the temperature separation was partially discussed based on the temperature distribution in the radial direction. This study aimed to explain the principle of energy separation in the vortex tube. To do so, the relative contributions of the radial pressure gradient, axial pressure gradient, and viscous dissipation to the temperature separation were investigated using numerical simulations and energy equation analysis. The results indicated that the axial pressure gradient in the near-axis region was the major contributor to an increase in hot exit temperature. In addition, the reason for the increase in hot exit temperature with an increase in cold mass fraction was explained. The reason for the decrease in cold exit temperature with an increase in cold mass fraction was also explained.

Objectives: To determine the effect of oral administration of porcine placental extract (PPE) on the menopausal symptoms of Korean women. Materials and methods: This study was a multicenter, randomized double-blind placebo-controlled trial. A hundred menopausal Korean women were randomly allocated either to the PPE 400 mg per day or the control group during 12 weeks of the study period. Menopausal symptoms were evaluated using the Kupperman Index (KMI). Results: The KMI decreased after 12 weeks in both groups; however, the difference in the changes was not statistically significant. Among overweight or obese women whose body mass index (BMI) was 23 kg/m2 or higher, the KMI decreased more significantly in the PPE group than placebo group after 12 weeks (−18.52 ± 9.09 vs −11.40 ± 10.68, P

OBJECTIVE Gabapentin is used to treat vasomotor symptoms (VMS) in postmenopausal women with contraindications to hormonal therapy or who prefer alternatives. We investigated the efficacy and tolerability of gabapentin for treating menopausal hot flushes via a meta-analysis. METHODS We searched the PubMed, MEDLINE, EMBASE, and CENTRAL databases for English-language articles published until June, 2018. The following search terms were used: "menopause," "hot flushes," "vasomotor symptoms," "gabapentin," and "non-hormonal therapy." Primary outcomes were frequency, duration, and composite score of hot flushes. Secondary outcomes were adverse effects and dropout rate. We estimated the standardized mean difference (SMD) and combined odds ratio (OR) using fixed or random-effects models, depending on study heterogeneity. Subgroup and meta-regression analyses of gabapentin dosage were performed. RESULTS We included seven randomized controlled trials that compared single-agent gabapentin with placebo for treating hot flushes in the meta-analysis. Women who received gabapentin reported a significantly greater reduction in the frequency (SMD 2.99 [95% confidence interval 2.01-3.98], P

We describe a case of a rupture-mediated large uterine defect, which occurred on the 30th gestation week presenting a protruding amniotic sac sac without fetal compromise after a laparoscopic electromyolysis.A 28-year-old woman in her 30th week of gestation (gravida 2, para 0) presented with whole abdominal and right lower quadrant pain at Sanggye Paik Hospital. Ultrasound examination showed normal amniotic fluid and placentation but with breech presentation. She had undergone laparoscopic right ovarian cystectomy due to endometriosis 5 years earlier. Cardiotocography revealed an intermittent variable deceleration and no uterine contraction. Magnetic resonance imaging ruled out acute appendicitis. Four hours later, we observed a protrusion of the amniotic sac with the fetal head through a large uterine defect on magnetic resonance imaging, and performed emergency cesarean section. A boy was delivered without fetal compromise. During the cesarean section, multiple myometric wall defects and thinning were identified. After reconstruction of the uterine wall, the flaccid uterus bled persistently; thus, a cesarean hysterectomy was performed. Packed red cells and frozen plasma were transfused. The mother and neonate had uneventful puerperal and neonatal courses, respectively. After cesarean hysterectomy, we were informed that the mother had undergone a combined laparoscopic electromyolysis during the laparoscopic right ovarian cystectomy. Three years later, the child showed normal neural development.Before myomectomy or electromyolysis, patients should be informed of the possibility of uterine rupture during subsequent pregnancies. If a pregnant woman has abdominal pain, clinicians should take a detailed history of uterine surgery and consider uterine rupture. Although, fortunately, the outcomes in this case were uneventful, urgent delivery is required when uterine rupture is diagnosed.

Advancement in wearable healthcare technology allows a digital revolution in healthcare that is intended to extend life length and improve life quality. Until now, numerous efforts for wearable device-mediated healthcare systems have been focused on achieving accurate monitoring and robust operation by developing cutting-edge biosensors rather than by optimizing the placement position of well-established biosensors. Much therefore still remains unclear about the optimal position involved in biosensor placement. This leads to the need for systematic optimization of biosensor placement position. Here, the placement positions of 2 biosensor arrays (i.e., ECG-TC array and PPG-TC array) are optimized to achieve high-accuracy measurement and high-robustness operation in monitoring both body temperature and heart rate, which are commonly measured as core vital signs in wearable healthcare systems. The ECG-TC array is composed of an electrocardiography (ECG) sensor (for heart rate measurement) and a thermocouple (TC) sensor (for body temperature measurement) while the PPG-TC array consists of a photoplethysmography (PPG) sensor and a TC sensor. 34 major parts in the human body are scored in terms of monitoring accuracy (MA) and operational robustness (OR), which results in the MA index and OR index. Next, the body part having the maximum value, calculated as the product of two indices, is determined as the optimal placement position. The MA index is calculated from the signal magnitude of each biosensor and the OR index is assessed by quantifying the user accessibility, skin extensibility, and perspiration weight of each body part. Our study shows that the ECG-TC array needs to be placed on armpit, chest, and back thigh and the PPG-TC array on thumb, finger, and ear. This means the optimal placement position of biosensor-based wearable healthcare systems is affected by a combination of different biosensors. The findings of this study are expected to contribute to better understanding of biosensors and lead to further improvement in wearable healthcare devices.

For polydimethylsiloxane (PDMS), a formation of interconnected pores and an addition of Silwet L-77 are, respectively, made as physical treatment and chemical one to change the material properties involved in the water permeable flow through PDMS. Here, we investigate a change in the water permeable flow through PDMS induced by physicochemical treatment. 28 kinds of physicochemically treated PDMS (pc-PDMS) blocks having different pore sizes of 50–500 µm and different Silwet L-77 concentrations of 0.0–8.0 wt% are prepared using a pressure-assisted compaction and NaCl particle-leaching technique. The values of mass flow rate and flow delay are obtained from pressure-driven water flow through pc-PDMS blocks as indexes for characterizing their water permeable flow. Our physicochemical treatment successfully controls the water permeable flow through PDMS, which means that pc-PDMS can be used for the development of powerless microfluidic regulators for aqueous chemicals in micro-total analysis systems (µ-TAS).

We investigate the impact of gate-stack engineering using W/ZrO2/Al2O3 on the performance of planar-type InGaAs tunneling field-effect transistors (TFETs). It is shown that 1-nm-thick capacitance equivalent thickness (CET) with low leakage current is achieved by using ZrO2 with the dielectric constant of around 40 on In0.53Ga0.47As. On the other hand, the reduction of Dit by insertion of ALD 1–5 cycle Al2O3 interfacial layers (ILs) is found to be mandatory for obtaining TFET performance enhancement. The planar-type InGaAs TFETs using the ZrO2/Al2O3 IL gate-stack with CET of 1 nm exhibit the minimum subthreshold swing (S. $\text{S}_{\min }$ ) of 55 mV/dec and ${I}_{ \mathrm{\scriptscriptstyle ON}}$ of $0.88~\mu \text{A}/\mu \text{m}$ ( ${V}_{\text {G}}$ – ${V}_{ \mathrm{\scriptscriptstyle OFF}}= \text {0.5}$ V, ${V}_{\text {D}}= \text {0.2}$ V, and ${I}_{ \mathrm{\scriptscriptstyle OFF}}= \text {10}$ pA/ $\mu \text{m}$ ). Furthermore, the ZrO2/Al2O3 IL gate-stack is applied to the optimized In0.75Ga0.25As quantum well (QW) channel TFETs. The low S. $\text{S}_{\min }$ of 50 mV/dec and high ${I}_{ \mathrm{\scriptscriptstyle ON}}$ of $1.2~\mu \text{A}/\mu \text{m}$ ( ${V}_{\text {G}}$ – ${V}_{ \mathrm{\scriptscriptstyle OFF}}= \text {0.5}$ V, ${V}_{\text {D}}= \text {0.2}$ V, ${I}_{ \mathrm{\scriptscriptstyle OFF}}= \text {10}$ pA/ $\mu \text{m}$ , and CET = 1.1 nm) are demonstrated by combing the present ZrO2-based gate-stack with the optimum In0.75Ga0.25As QW channel structure.

Objective This study aimed to investigate incidence and risk for venous thromboembolism (VTE) according to primary treatment in women with ovarian cancer. Methods We selected 26,863 women newly diagnosed with ovarian cancer between 2009 and 2018 from the Korean Health Insurance Review and Assessment Service databases. During the total follow-up period and the first six months after initiation of primary treatments, incidence and risk of VTE were evaluated according to primary treatment as no treatment, surgery, radiotherapy, or chemotherapy. Results The mean follow-up period was 1285.5±6 days. The VTE incidence was highest in women who underwent chemotherapy (306 per 10,000 women). Among women who underwent surgery, VTE was highest in surgery with neoadjuvant chemotherapy (536 per 10,000 women), followed by surgery with adjuvant chemotherapy (360 per 10,000 women) and surgery alone (132 per 10,000 women). During the first 12 months, monthly incidence of VTE decreased. Compared with women with no treatment, risk of VTE significantly increased in women undergoing chemotherapy (HR 1.297; 95% CI, 1.08–1.557; P = 0.005) during the total follow-up period and decreased in women undergoing surgery (HR 0.557; 95% CI, 0.401–0.775; P Conclusions In this large Korean cohort study, incidence and risk of VTE were highest in women with ovarian cancer who underwent chemotherapy and surgery with neoadjuvant chemotherapy as a primary cancer treatment. Incidence of VTE decreased over time.

Background To identify sarcopenia as a predictive prognostic factor of ovarian cancer in terms of survival outcome in patients with early-stage ovarian cancer. Methods Data of Konkuk University Medical Center from March 2002 to December 2017 were reviewed retrospectively. Eighty-two patients who underwent surgery due to early-stage (International Federation of Gynecology and Obstetrics stage I/II) ovarian cancer and had computed tomography (CT) images taken at the initial diagnosis were included. The initial CT scan images were analyzed with SliceOmatic software (TomoVision). A sarcopenia cutoff value was defined as a skeletal muscle index of ≤ 38.7 cm2/m2. Overall survival (OS) times were compared according to the existence of sarcopenia, and subgroup analyses were performed. Results A Kaplan-Meier analysis showed a significant survival disadvantage for patients with early-stage ovarian cancer when they had sarcopenia (P < 0.001; log-rank test). Sarcopenia remained a significant prognostic factor for OS in early-stage ovarian cancer, in a Cox proportional hazards model regression analysis (HR, 21.9; 95% CI, 2.0–199.9; P = 0.006). Conclusion This study demonstrated that sarcopenia was predictive of OS in patients with early-stage ovarian cancer. Further prospective studies with a larger number of patients are warranted to determine the extent to which sarcopenia can be used as a prognostic factor in ovarian cancer., Graphical Abstract

A functional polymer-matrix composite (PMC) with controllable material properties is emerging as a promising material for the smart sensors in structural health monitoring (SHM). A GnF/PDMS composite is developed as a new functional PMC by blending graphite nanoflakes (GnFs) with polydimethylsiloxane (PDMS) where GnF and PDMS are used as a reinforcing/conductive filler and an elastic host matrix, respectively. We characterize the mechanoelectrical property-controllable GnF/PDMS composite, mainly focusing on the following issues: (i) determination of the best solvent for the preparation of a GnF/PDMS composite solution, (ii) exploration of changes in the mechanoelectrical properties of the functional PMC induced by variations in the aspect ratio (AR) and concentration of GnF. Among 9 kinds of common solvents, benzene shows both high GnF dispersibility and excellent PDMS compatibility, therefore being chosen as the optimal solvent. Variations in GnF AR (223–1017) and GnF concentration (1.0–25.0 wt.%) lead to significant changes in the elastic modulus, fracture strain, electrical conductivity, and gauge factor of the functional PMC in the ranges of 0.39–13.8 MPa, 0.09 to 2.54, 6.97 × 10−6 to 221.0 S/m, and 6 to about 37,000, respectively. The empirical models for predicting the mechanoelectrical properties of the functional PMC are also intensively studied. Our GnF/PDMS composite is expected to be used as a functional PMC for the development of smart sensors that detect deformation and fracture in structures.

The graphite nanoflake (GnF)-reinforced polydimethylsiloxane (PDMS) composites (GnF/PDMS composites) are developed as new polymer matrix composites (PMCs) with controllable mechanoelectrical properties. Here, we investigate the effect of GnF concentration on the mechanoelectrical properties (i.e., elastic modulus, fracture strain, and conductivity) of GnF/PDMS composites; the change in the surface morphology of GnF/PDMS composites caused by a variation in GnF concentration is also explored. The mechanoelectrical properties are measured by performing tensile tests on the GnF/PDMS composite specimens with different GnF concentrations of 5.0, 10.0, 12.5, 15.0, 20.0, and 25.0 wt.%. The surface morphology is analyzed in terms of internal void formation and surface roughness. The elastic modulus is measured to be in the range of 1.62 to 13.8 MPa which is proportional to GnF concentration, while the fracture strain and electrical conductivity are respectively characterized to be in ranges of 0.09 to 2.09 and 0.3 to 221.0 S/m which are in inverse proportion to GnF concentration. An increase in GnF concentration leads to increases in internal voids’ amount and surface roughness. The GnF/PDMS composites can be used as sensing materials for detecting both small and large deformations in a variety of engineering applications.

The GnF/SU-8 composites are new polymer matrix composites (PMCs) composed of graphite nanoflakes (GnFs) bound together by SU-8 photoresist. The PMCs therefore have excellent ultraviolet (UV) photopatternability and high electrical properties. In spite of the unique material properties of GnF/SU-8 composites, much still remains uncertain about their controllability in both UV photopatternability and electrical properties. Here, we investigate 7 kinds of GnF/SU-8 composites having different GnF concentrations of 5.0 to 25.0 wt.% to characterize the changes in the UV photopatternability (i.e., polymerized thickness and photopattern quality) and electrical conductivity of GnF/SU-8 composites caused by a variation in GnF concentration. The polymerized thickness of GnF/SU-8 composites is measured to be in the range of 4.06 to 23.99 μm, which is inversely proportional to GnF concentration and also directly proportional to UV dose (i.e., 345 to 3,450 mJ/cm2) because of the screening effect of GnF existed in the composites; the photopattern quality at the edge is in inverse proportion to GnF concentration. An increase in GnF concentration leads to a significant change in the electrical conductivity of GnF/SU-8 composites in a proportional way (up to 25.34 S/m). The GnF/SU-8 composites are expected to be widely used as UV photopatternable and electrically conductive PMCs for diverse engineering applications.

A mosquito is known to precisely and easily insert its proboscis to the human skin by pressing down a labium and vibrating a fascicle bundle. Its advanced skin-piercing mechanisms indicate that skin resistance to the insertion of needle-like objects can be changed by the application of mechanophysical stimuli. Here, we characterize the effect of the application of mechanophysical stimuli on skin resistance to microneedle insertion to find clues for inserting a microneedle in a deep and precise fashion with low force. Microneedles with a diameter of 60-140µm are inserted at a velocity of 0.1-2.0mm/s to full-thickness porcine skins while either uniaxial/equibiaxial stretch of 0-20% or mechanical vibration at a frequency of 1 to 1000Hz and an amplitude of 1-10µm is applied to the skins as static or dynamic mechanophysical stimulus, respectively. The values of force and depth at two events of skin puncture and maximum penetration are measured to explore changes in skin resistance induced by the application of external stimuli. The static mechanophysical stimulus applied to the skin mainly affects the precision of microneedle insertion; the application of dynamic mechanophysical stimulus controls the value and deviation of skin resistance to microneedle insertion. The application of mechanophysical stimuli, inspired from a mosquito, therefore allows a microneedle to be deeply and easily inserted to the skin in a controlled way. The findings will have broad impacts on microneedle-mediated applications and lead to an in-depth understanding of skin biomechanics.

Porosity is suppressible but unavoidable in manufacturing nanocomposites, therefore affecting their mechanical properties like intrinsic properties and other filler-related factors. Despite all the efforts, it is still regarded as challenging to develop theoretical models for mechanical properties of filler-reinforced nanocomposites which consider void defects created during manufacturing process. Here, graphite nanoflake/polydimethylsiloxane (GnF/PDMS) nanocomposites for paint-on applications are manufactured with different processing methods (i.e., solvent casting, hand lay-up, and spray lay-up) to address imperfections involved in each process and their implication to mechanical properties. The manufacturing processes were found to have almost no alternation on filler-related features (i.e., size, orientation, and distribution) except porosity. The evolution of a porosity is best modeled with the logistic function. We establish a set of prediction models for elastic modulus, fracture strength, and elongation at break by combining the previous models (i.e., Tsai-Hahn, Piggott-Leidner, and Landel-Nielsen models) with the logistic function on porosity. The proposed models are in good agreement with the experimental data on GnF/PDMS nanocomposites. The effect of process method on surface morphology is also discussed.

Low power consumption is one of the most important requirements for present and future integrated systems. Here, reduction in supply voltage is most effective in power reduction. Low supply voltage operation of charge-based logic switch devices can be achieved by steep slope devices with lower sub-threshold swing (S.S.) than CMOS. For this purpose, tunnel FETs (TFETs) have recently stirred a strong interest [1, 2], because of the high compatibility with CMOS platform. Here, materials with small and/or direct band gap such as III-V and Ge are preferred to enhance Ion of TFETs. In addition, type-II hetero-structures are known to be effective in boosting the TFET performance [1-3]. One of the critical technological challenges of pn-junction-based TFETs is the source junction engineering allowing us to form the source junctions with steep impurity profiles and low defect density for optimal Ge/III-V and/or hetero-interface materials. In addition, another key factor is low defect densities in the channel/junction regions and at the MOS interfaces. The MOS interface defects can include fast interface states, slow states and tail states near the band edges, while the reduction in the defect densities is not easy for other materials than Si. Thus, the channel and gate stack engineering for realizing defect-less structures are also quite important. From the above viewpoints, we are currently working for the following material systems and source doping technologies [2-4], (1) InGaAs TFET with Zn diffusion source (2) GaAsSb (source)/InGaAs (channel) TFETs with Be in-situ doping (3) Ge (source)/strained Si (channel) TFETs with B in-situ doping. Here, Zn diffusion into InGaAs can automatically form pn junctions with steep Zn profile, because of the diffusion constant of Zn strongly dependent on Zn concentration [5, 6]. We experimentally confirmed the steep Zn profile and lower leakage current of InGaAs p-n junctions by solid phase diffusion from SOG films, attributed to the defect-less junction formation. Quantum-well InGaAs/InAs(3nm)/InGaAs n-TFETs with the Zn-diffused source regions and W/HfO2/Al2O3 gate stacks have exhibited the minimum S.S. value of 55 mV/dec and I60 (maximum source/drain current with S.S. less than 60 mV) of 0.7 nA/um at room temperature [3, 6]. In comparison with InGaAs homo-junction TFETs, III-V TFETs composed of type-II hetero-structures, GaSb/InAs and GaAsSb/ InGaAs, are expected to provide superior electrical characteristics, because of the smaller effective bandgap. We fabricated vertical n-TFETs using in-situ Be-doped p+-GaAs0.51Sb0.49/ In0.53Ga0.47As grown on InP by MOMBE [3, 7]. The steep Be profile of 11 nm/dec. is obtained, thanks to the in-situ doping of Be during the GaAsSb growth. We confirmed the operation of GaAsSb/InGaAs TFETs through observation of the negative differential resistance under forward bias condition. However, high leakage current attributable to defects in the source junction significantly degrades the performance at 297 K. The characteristics at 20 K with S.S. of 82 mV/dec. are regarded as the TFET performance dominated only by tunneling. Another type of type-II hetero-interface n-TFETs has been realized by p+Ge/strained SOI structures [3, 4, 8, 9]. Here, higher valence band edge of the source due to Ge and lower conduction band edge of the channel due to bi-axial tensile strain are combined to form the type-II band line-up. p+Ge/SOI with tensile strain of 0.8 and 1.1 % were fabricated by using bi-axial strained SOI substrates and in-situ B doping during Ge MBE growth. The higher Ion and lower S.S.min were obtained by applying tensile strain. The unstrained, 0.8 and 1.1 % strained SOI TFETs after 400 oC PMA [9] yield S.S.min of 69, 48 and 29 mV/dec. and Ion/Ioff of 4.4, 2.2 and 3.7x107, respectively, at room temperature. This work has partly been supported by JST-CREST. The authors would like to thank Drs. M. Yokoyama, O. Ichikawa, H. Yamada and T. Yamamoto in Sumitomo Chemical Corporation, Drs. M. Mitsuhara, H. Sugiyama, Hoshi and H. Yokoyama in NTT for their collaborations. References [1] A. C. Seabaugh et al., IEEE Proc. 98, 2095 (2010) [2] S. Takagi et al., Symp. VLSI Tech., T22 (2015) [3] S. Takagi et al., IEDM, 516 (2016) [4] S. Takagi et al, Solid State Electron. 125, 82 (2016) [6] S. Takagi et al, IEDM, 516 (2016) [5] M. Noguchi et al., J. Appl. Phys. 118, 045712 (2015) [6] D. H. Ahn et al., Symp. VLSI Tech., 224 (2016) [7] T. Gotow et al., SSDM, 21 (2016) [8] M. Kim et al., Thin Solid Films 557, 298 (2014) [9] M. Kim et al., IEDM, 331(2014)

Diverse surface/bulk treatments have been introduced to overcome the interfacial limitations of pristine (or untreated) PDMS, thus extending the possible applications of PDMS in micro/nano device development. Despite of extensive efforts, the temporal wetting change of PDMS induced by surface/bulk treatments still remains incompletely understood. We prepared 3 kinds of physicochemically treated PDMS blocks using widely used surface/bulk treatments-3D interconnected pore network formation, biocompatible surfactant (i.e., Silwet L-77) addition, and combination of both. Their wetting nature was characterized by measuring the time profile of water contact angle. A 3D interconnected pore network formation produced a time-invariant decrease in PDMS wettability; a surfactant addition increased the PDMS wettability in a time-variant way; a combination of pore network formation and surfactant addition had a combined effect. The measurement led to the successful development of a model for predicting the temporal wetting change in PDMS caused by variances in pore size and surfactant concentration. The accuracy of our model was verified by comparing experimental results with model predictions. This model will result in better understanding of polymer interface.

A skin-perforable dissolving microneedle is a promising mediator for painlessly delivering active pharmaceutical compounds across the skin. All the microneedle manufacturing processes so far, however, are much sensitive to input variation and unfavorable for make-to-order approach. Here, a robust method for fabricating mass-customizable master molds is developed to prepare sharp-tipped biodegradable polymer microneedles. Our approach combines the predrying and chip casting (PCC) of an ultrathick photoresist layer with a substrateless, inclined, and rotational exposure (SIR exposure). The PCC achieves the uniform reduction of solvent across the photoresist thickness which is critically required for the formation of a sharp tip; the SIR exposure creates master molds whose geometry is easily customizable and virtually insensitive to a variation in ultraviolet (UV) exposure dose. A theoretical model for the spatiotemporal distribution of UV dose under SIR exposure is established to show the technological superiority of our method. Next, our method's applicability is proven by fabricating a set of poly(lactic-co-glycolic) acid (PLGA) microneedles and performing both porcine skin penetration test and their in vitro degradation test. Our approach is verified to be robust in manufacturing mass-customizable molds for skin-perforable dissolving microneedles and to have high compatibility with almost all existing biodegradable polymers. The findings of this study lead to both a significant growth of dissolving microneedle-mediated drug delivery and better understanding of drug release kinetics.

A successful development of high-performance multilevel microdevices is attributed to the outstanding physical properties of a polycrystalline silicon (poly-Si) film which can be tailored by its process conditions. Here, we select deposition temperature and post-deposition annealing treatment as critical process parameters, followed by investigating their effects on both structure properties and chemical-mechanical planarization (CMP) manufacturability of a poly-Si film. Experimental samples are prepared through low-pressure chemical vapor deposition (LPCVD) poly-Si deposition at different temperatures of 545–625 °C and thermal annealing treatment at 1050 °C under nitrogen atmosphere. At first, the poly-Si sample is inspected to characterize changes in macroscopic structure properties caused by the critical process parameters, together with changes in its surface morphology and grain boundary density. Next, the sample is polished to quantify changes in poly-Si CMP manufacturability such as material removal rate (MRR) and surface roughness. A relation between changes in microscopic features and changes in macroscopic properties is also discussed in depth. A poly-Si film deposited at 625 °C and then thermally annealed at 1050 °C shows significant improvement in both structure and CMP manufacturing aspects. The findings of this paper can potentially have a significant impact on developing poly-Si-based multilevel microdevices.

There is an explosion of interest in characterizing cell adhesion process and the mechanochemical players that is critical to a wide range of physiological and pathological consequences. Much, however, still remains uncertain and controversial about the quantitative measurement of cell adhesion strength (i.e., cell-substratum adhesion force, cell-cell adhesion force, etc.). The main reason for this deficit is a lack of well-established and comprehensive experimental methods that quantitatively measure cell adhesion strength at cellular and even molecular levels. This leads to the need for conducting a literature review on the methods for characterizing the adhesion force of anchorage-dependent cells. In this review article, we discern and critique available techniques for measuring cell adhesion strength that is required for an adherent cell (or cells) of interest to detach from the neighboring cell or the substratum. This review focuses on recent advances in the technique for measuring cell adhesion strength to weigh up the strengths and weaknesses of each technique, together with a brief description for the biological aspects of cell adhesion process. The summary of this article might help us both to develop a standard method for measuring cell adhesion strength and to broaden and deepen our understanding of cell adhesion process.