Psychometric Validation of the Korean Version of Structured Interview for Post-traumatic Stress Disorder (K-SIP)

For diagnosis and management of post-traumatic stress disorder (PTSD), the easily administered assessment tool is essential. Structured Interview for PTSD (SIP) is a validated, 17-item, simple measurement being used widely. We aimed to develop the Korean version of SIP (K-SIP) and investigated its psychometric properties. Ninety-three subjects with PTSD, 73 subjects with mood disorder or anxiety disorder as a psychiatric control group, and 88 subjects as a healthy control group were enrolled in this study. All subjects completed psychometric assessments that included the K-SIP, the Korean versions of the Clinician-Administered PTSD Scale (CAPS) and other assessment tools. The K-SIP presented good internal consistency (Cronbach's α=0.92) and test-retest reliability (r=0.87). K-SIP showed strong correlations with CAPS (r=0.72). Among three groups including PTSD patients, psychiatric controls, and normal controls, there were significant differences in the K-SIP total score. The potential cut-off total score of K-SIP was 20 with highest diagnostic efficiency (91.9%). At this point, the sensitivity and specificity were 95.5% and 88.4%, respectively. Our result showed that K-SIP had good reliability and validity. We expect that K-SIP will be used as a simple but structured instrument for assessment of PTSD

A Validation Study of the Korean Version of SPAN

Purpose: The SPAN, which is acronym standing for its four components: Startle, Physiological arousal, Anger, and Numbness, is a short post-traumatic stress disorder (PTSD) screening scale. This study sought to develop and validate a Korean version of the SPAN (SPAN-K). Materials and Methods: Ninety-three PTSD patients (PTSD group), 73 patients with non-psychotic psychiatric disorders (psychiatric control group), and 88 healthy participants (normal control group) were recruited for this study. Participants completed a variety of psychiatric assessments including the SPAN-K, the Davidson Trauma Scale (DTS), the Clinician-Administered PTSD Scale (CAPS), and the State-Trait Anxiety Inventory (STAI). Results: Cronbach's alpha and test-retest reliability values for the SPAN-K were both 0.80. Mean SPAN-K scores were 10.06 for the PTSD group, 4.94 for the psychiatric control group, and 1.42 for the normal control group. With respect to concurrent validity, correlation coefficients were 0.87 for SPAN-K vs. CAPS total scores (p<0.001) and 0.86 for SPAN-K vs. DTS scores (p<0.001). Additionally, correlation coefficients were 0.31 and 0.42 for SPAN-K vs. STAI-S and STAI-T, respectively. Receiver operating characteristic analysis of SPAN-K showed good diagnostic accuracy with an area under the curve (AUC) of 0.87. The SPAN-K showed the highest efficiency at a cutoff score of 7, with a sensitivity of 0.83, a specificity of 0.81, positive predictive value (PPV) of 0.88, and negative predictive value (NPV) of 0.73. Conclusion: These results suggest that the SPAN-K had good psychometric properties and may be a useful instrument for rapid screening of PTSD patients.This study was supported by a grant of the Korean Academy of Anxiety Disorders, Korean Neuropsychiatric Association, and Korean Research Foundation (2006-2005152), Republic of Korea

LED와 SU-8 광 도파관을 결합한 광 효율을 증가시킨 실리콘 옵트로드에 관한 연구

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 김용권.빛을 사용하여 신경세포를 자극하는 광유전학이 수립된 이후, 레이저와 광섬유가 결합된 신경자극 시스템이 빛을 세포에 전달하는 소자로 흔히 사용되고 있다. 하지만, 최근 무선으로 광 자극을 하려는 시도에서 레이저 시스템의 높은 전력소비와 부피가 큰 사이즈는 무선시스템 발전의 장애물이 되고 있다. 이를 해결하기 위해 초소형 발광다이오드를 장착한 실리콘 옵트로드가 각광받고 있으나, 이 또한 광원에서 발생하는 열에 의한 세포손상이 문제가 되고 있다. 본 연구에서는 무선시스템에 호환이 가능하고, 광원에서 발생된 열에 의한 세포 손상을 해결할 수 있는 발광다이오드와 도파관을 결합한 실리콘 옵트로드를 제안한다. 해당 소자가 만들어질 경우 관건은 신경세포 자극을 위한 최소 조도 확보이다. 발광다이오드의 넓은 광 분산 각도와, 광원과 도파관의 낮은 결합효율은 최소 조도 확보를 어렵게 하기 때문에, 이를 해결하기 위해 렌즈를 활용하여 결합효율을 높이고자 한다. 반도체 공정에서 3차원 렌즈를 제작하는 것은 매우 어렵기 때문에, 두 개의 제작가능한 렌즈를 만들어 그 효과를 보완하고자 한다. 실린더 형태의 렌즈와 감광제로 사용되는 다중체 렌즈를 사용하여 수직과 수평방향으로 빛을 모으는 역할을 분담할 수 있다. 실린더 렌즈는 수직으로 빛을 집속하고, 다중체 볼록렌즈는 수평방향으로 빛을 집속한다. 처음으로 실리콘 식각 시 SU-8 투과율이 낮아지는 현상을 보고하였으며, 이는 실리콘 식각 플라즈마로 형성된 자외선에 의해 발생되는 것임을 보고하였다. 낮은 투과율 문제를 회피하기 위해, 공정 순서를 최적화하여 변경하는 방법으로 해결하였다. 실린더 렌즈의 정교한 부착의 경우, 자체적인 정렬 기계를 만들어 해결하였다. 마지막으로 유연한 인쇄회로기판을 소자에 부착하고, 3차원 프린트를 사용하여 소자를 통합했다. 제작된 소자의 광 세기 측정을 한 결과 실린더 렌즈와 SU-8 렌즈의 광 결합효율이 각각 6.7 dB, 6.6 dB 증가하는 것을 확인하였다. 이론적으로 계산한 광효율이 각각 6.1 dB, 7 dB 인 것을 봤을 때, 실린더 렌즈의 측정된 광 효율이 0.6 dB 높은 것을 확인할 수 있었다. 이는 발광다이오드의 넓은 분산각도와 렌즈를 사용한 광선의 높은 기울기로 인해 skew ray가 meridional ray에 비해 훨씬 더 많을 것이라는 가정에 의해 이론이 계산되었기 때문이다. 발광다이오드에 약 50 mA의 전압이 주어졌을 때, 도파관 끝의 조도는 약 2.7 mW/mm2로 측정되었다. 이를 바탕으로 빛 확산에 의한 전극 위의 조도는 0.5 mW/mm2 이상이 될 것으로 계산이 되었다. 실리콘 옵트로드는 1x4 어레이 형태로 쉥크가 형성되어 있으며, 각 쉥크마다 4개의 기록전극이 배치되어 있다. 기록전극들은 전극 임피던스를 낮추고 노이즈 대비 높은 신호를 얻기 위해 산화 이리듐을 도금하였다. 임피던스는 기존 2.57 MΩ에서 43.6 kΩ으로 낮아졌다. 제작된 실리콘 옵트로드는 형질전환된 쥐의 해마에 삽입되었다. 기록된 생체신호는 광 자극에 동기화되어 반응하는 것을 측정하였다. 따라서 본 연구에서 고안된 실리콘 옵트로드의 광유전학 사용가능성이 확인되었으며, 옵트로드 장치의 무선시스템의 적용 가능성 또한 증명되었다.A laser-optical fiber-coupled optogenetic neurostimulation system is generally chosen for the light delivering method in optogenetics which stimulates photosensitive neurons using light. However, due to the high-power consumption and bulkiness of the laser control system, wireless optogenetics neuromodulation systems have difficulties in equipping laser modules. To achieve the wireless capability of optical stimulation, optrodes with μLEDs (micro light-emitting diode) were reported. One huge drawback of μLEDs is the thermal damage of neuronal cells due to the heat generated by μLEDs. In this study, an LED and SU-8 waveguide coupled silicon optrode array is presented, which is compatible with a wireless system and avoids heat damage to neuronal cells. The major problem of the suggested scheme is the large beam dispersion angle of LED and the low coupling efficiency of the source and waveguide. To increase the light irradiance at the SU-8 waveguide tip, an LED and polymer waveguide coupled silicon optrode with lenses has been presented. Since three-dimensional lens MEMS fabrication is very hard to make, two MEMS compatible lenses were employed to focus light in the vertical and lateral directions. The unique polymer lens pattern and cylindrical lens were placed between a conventional LED and SU-8 waveguide to enhance the light coupling efficiency. The roles of cylindrical lens and SU-8 plano-convex lens are light focus on vertical direction and lateral direction, respectively. Throughout the study, the MEMS silicon optrode fabrication process was stabilized successfully. The SU-8 transmittance degradation issue at the silicon etching process is defined for the first time, which is caused by ultraviolet light while silicon plasma etching. Optimizing the fabrication step solved the issue effectively. The unique solution of achieving precise alignment of cylindrical lens was also provided. At last, bonding a flexible printed circuit board and a custom three-dimensional housing structure reduced the size of the silicon optrode device. Power measurement of the light at the optrode tip showed significant improvement of the light coupling efficiency through the suggested lenses. Measured coupling efficiency increased by the cylindrical lens and the SU-8 plano-convex lens were 6.7 dB and 6.6 dB respectively. The theoretical light coupling efficiency enhancement of the cylindrical lens and the SU-8 plano-convex lens were 6.1 dB and 7 dB, respectively. The theoretical calculation of cylindrical lens efficiency was lower than the measurement, due to the assumption that the portion of meridional rays were much less than the portion of skew rays at the SU-8 waveguide. Since LED has wide dispersion angle and the lenses used in the device make the rays precipitously, the above assumption was established. When 50 mA current was applied to the 470 nm wavelength LED, the light irradiance of 2.7 mW/mm2 was measured at the SU-8 waveguide tip. The light irradiance above the electrodes has been analyzed using geometrical dispersion equation by MATLAB code. It showed that all locations above the electrodes have light irradiance greater than 0.5 mW/mm2. The silicon optrode is consist of 1x4 optrode shank array, and each optrode contains four recording electrodes and one optical waveguide. Recording electrodes were iridium oxide electroplated to lower the impedance and improve the signal to noise ratio. The average impedance dropped from 2.57 MΩ to 43.6 kΩ. The silicon optrode was inserted into transgenic rat hippocampus CA1 and CA2 region. The recorded neural spikes were synchronized successfully to the optical stimulation. In-vivo experiment proved the optogenetics feasibility and wireless compatibility of the suggested LED and SU-8 waveguide coupled silicon optrode.1. Introduction 1 1.1. Background 1 1.1.1. Optogenetics 1 1.1.2. Theory 2 1.2. Conventional optogenetics device 5 1.2.1. Early optogenetics device 5 1.2.2. Laser-based MEMS optrode 7 1.2.3. μLED-based MEMS optrode 8 1.2.4. LED and waveguide coupled optrode 11 1.2.5. Summary of conventional methods 13 1.3. Research objectives 16 1.4. Research proposal 18 2. Design 20 2.1. Optical part design 20 2.1.1. Optical properties 20 2.1.2. Vertical focusing lens design 21 2.1.3. Lateral focusing lens design 26 2.1.4. LED choice 28 2.1.5. Expected coupling efficiency at the waveguide outlet 29 2.2. Silicon shank and body design 31 2.2.1. Substrate selection 31 2.2.2. Silicon optrode dimension design 32 3. Device fabrication 34 3.1. MEMS silicon optrode fabrication process 34 3.1.1. Substrate preparation and insulation layer deposition 34 3.1.2. Gold electrode patterning 35 3.1.3. 2nd insulation deposition and etch 38 3.1.4. Aluminum pattern on handling layer 40 3.1.5. Device layer oxide and silicon etch 42 3.1.6. SU-8 waveguide fabrication 43 3.1.7. Handling layer silicon etch and buried oxide removal 44 3.2. Precision alignment of the cylindrical lens 48 3.3. Electrical interconnection and impedance improvement 51 3.3.1. Electrical interconnection 51 3.3.2. Impedance improvement 51 3.4. System integration 54 3.4.1. LED integration 54 3.4.2. Electrical connections 54 3.5. In-vivo experiment setup 56 3.5.1. Transgenic rat preparation 56 3.5.2. Electrophysiology recording system setup 57 4. Results 58 4.1. Optical characteristics measurement 58 4.1.1. Optical power measurement setup 58 4.1.2. Measurement analysis 58 4.2. In-vivo experiment and spike analysis 66 4.2.1. In-vivo insertion location and shank data 66 4.2.2. Custom MATLAB spike analyzer program 67 4.2.3. In-vivo experiment result 74 4.2.4. Fluorescent image verification 76 5. Discussion 78 5.1. Optical output power analysis 78 5.1.1. Theoretical value and measured data of lens efficiency 78 5.1.2. Theory and empirical data of irradiance at the waveguide tip 79 5.2. In-vivo experiment 80 5.2.1. Silicon optrode validity 80 5.2.2. Analyzation of experiment result from silicon shanks 80 5.2.3. Reinforcement of synaptic connections 81 5.2.4. Advantages of suggested silicon optrode 82 5.3. Wireless optogenetics neural interface 84 5.3.1. Analog front end circuit design 84 5.3.2. Wireless system design 85 5.3.3. PCB design 85 5.3.4. Receiver programming 91 5.3.5. PC software 92 6. Conclusion 94 Bibliography 97 국문 초록 103박

An Optimal Strategic Business Model for Small Businesses Using Online Platforms

As ecommerce continues to grow, small businesses are using a variety of platforms to secure potential consumers. However, it is important for small business owners to choose an efficient business model because of constraints such as technical problems. In this study, based on platform characteristics we divide online shopping platforms into different types as follows: (1) information brokerage services; (2) online malls; and (3) omni-channel platforms. The efficiency of each group is measured by stochastic frontier analysis, and the efficiency comparison between the groups is made using meta-frontier analysis. As a result of the study, it is found that the efficiency of small business owners increases as functional integration increases, satisfying utilitarian motivations. However, a platform with greater integration that has a social presence satisfying hedonic motivations improves the efficiency of all small businesses using the platform instead of just the efficiency of a marginal number of small business owners. This study, based on the dynamic capabilities viewpoint, suggests that the omni-channel platform represents the most sustainable approach for small business owners undergoing difficulties such as technological and organizational changes

Implantable Wireless Neural Interface for Multichannel Neural Recording and Optogenetic Neuromodulation

This paper presents a low cost, light-weight, and low power consuming wireless neural interface for multichannel neural recording and optogenetic neuromodulation with 470 and 589 nm light sources and a customizable pulse generator. To enhance the light coupling efficiency between the light emitting diode (LED) and 4 x 4 array of optical fibers, microlens array is used. Measured light intensity at the tip of the fiber array is 2.812 and 1.765 mW/mm(2) for 470 and 589 nm light sources, respectively. Optical fibers are assembled with 4 x 4 microlens array on a silicon die, which enables the illumination of relatively large area in the brain. To record the neural signal, two zero-drift operational amplifiers and 12-bit ADC (analog-to-digital converter) were used. The sampling frequency on each channel is 16 kHz. A +/- 160 mu V, 100 Hz sine wave in saline solution was successfully measured and wirelessly transmitted with the fabricated device.N

Highly Conductive and Flexible Gel Polymer Electrolyte with Bis(Fluorosulfonyl)imide Lithium Salt via UV Curing for Li-Ion Batteries

A series of new self-standing gel polymer electrolytes (SGPEs) were fabricated by ultraviolet (UV) curing and investigated for application in flexible lithium-ion batteries. Compared with traditional gel polymer electrolytes (combine with solvents or plasticizers), these new SGPEs were prepared simply by curing different weight ratios of lithium bis(fluorosulfonyl)imide (LiFSI) with a methacrylic linear monomer, poly (ethylene glycol) dimethacrylate (PEGDMA). Noticeably, there were no solvents or plasticizers combined with the final SGPEs. Owing to this, the SGPEs showed high flexibility and strong mechanical stability. Some paramount physicochemical and electrochemical characters were observed. The SGPEs demonstrated good thermal stability below 150 °C and an extremely low glass transition temperature (Tg) (around −75 °C). Moreover, plastic crystal behaviors were also identified in this study. Ultimately, the SGPEs demonstrated excellent ionic conductivity at room temperature, which proves that these new SGPEs could be widely applied as a prospective electrolyte in flexible lithium-ion batteries

Laser-induced acoustic wave generation/propagation/interaction in water in various internal channels

Short pulsed laser-induced single acoustic wave generation, propagation, interaction within a water-filled internal channel are experimentally and numerically studied. A large-area, short-duration, single-plane acoustic wave was generated by the thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid–solid interface and propagated at the speed of sound in water. Laser flash Schlieren photography was used to visualize the transient interaction of the plane acoustic wave in various internal channel structures ((a) sudden expansion and contraction channels, (b) bifurcating channels, (c) gradual contraction wall channels and (d) a cylinder). Fairly good agreement between the experimental results and numerical simulation is observed

Optrode Array for Simultaneous Optogenetic Modulation and Electrical Neural Recording

© 2022 JoVE Journal of Visualized Experiments.During the last decade, optogenetics has become an essential tool for the investigation of neural signaling due to its unique capability of selective neural modulation or monitoring. As specific types of neuronal cells can be genetically modified to express opsin proteins, optogenetics enables optical stimulation or inhibition of the selected neurons. There have been several technological advances in the optical system for optogenetics. Recently, it was proposed to combine the optical waveguide for light delivery with electrophysiological recording to simultaneously monitor the neural responses to optogenetic stimulation or inhibition. In this study, an implantable optrode array (2x2 optical fibers) was developed with embedded multichannel electrodes. A light-emitting diode (LED) was employed as a light source, and a microfabricated microlens array was integrated to provide sufficient light power at the tip of the optical fibers. The optrode array system comprises the disposable part and the reusable part. The disposable part has optical fibers and electrodes, while the reusable part has the LED and electronic circuitry for light control and neural signal processing. The novel design of the implantable optrode array system is introduced in the accompanying video in addition to the procedure of the optrode implantation surgery, optogenetic light stimulation, and the electrophysiological neural recording. The results of in vivo experiments successfully showed time-locked neural spikes evoked by the light stimuli from hippocampal excitatory neurons of mice.N

Silicon optrode array with monolithically integrated SU-8 waveguide and single LED light source

Objective. This paper presents a conventional light emitting diode (LED) and polymer waveguide coupled silicon optrode array. Approach. Unique lens design at the waveguide inlet enables a high light coupling efficiency with a single LED light source, and provides small power consumption compatible with a wireless optogenetic neuromodulation system. To increase the light intensity at the waveguide tip, a lensed waveguide is fabricated with epoxy-based photoresist SU-8, which has a plano-convex lens shape at the waveguide inlet to focus the light in the horizontal direction. In addition, a cylindrical lens is assembled in front of the waveguide inlet to focus the source light in the vertical direction. Main results. The glass cylindrical lens and SU-8 plano-convex lens increased the light coupling efficiency by 6.7 dB and 6.6 dB, respectively. The fabricated 1 x 4 array of optrodes is assembled with a single LED with 465 nm wavelength, which produces a light intensity of approximately 2.7 mW mm(-2) at the SU-8 waveguide outlet when 50 mA input current is applied to the LED. Each optrode has four recording electrodes at the SU-8 waveguide outlet. The average impedance of the iridium oxide (IrO (x) ) electroplated recording electrodes is 43.6 k omega. Significance. In-vivo experiment at the hippocampus region CA1 and CA2 demonstrated the capability of optical stimulation and neural signal recording through the LED and SU-8 waveguide coupled silicon optrode array.N