Smart Forensic Phone: Colorimetric analysis of a bloodstain for age estimation using a smartphone

Shin, Joonchul,Choi, Seoyeon,Yang, Jung-Sik,Song, Jaewoo,Choi, Jong-Soon,Jung, Hyo-Il Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.243 No.-

<P><B>Abstract</B></P> <P>Estimating the age of a bloodstain is important for tracking down the true perpetrator of a crime from among the suspects. The current methods available for this estimation suffer from several shortcomings, including the time required and low accuracy. A mobile detection system, named <I>Smart Forensic Phone,</I> developed in this study enabled us to rapidly and precisely estimate the age of a bloodstain. We placed blood on five different materials (wallpaper, fabric, glass, wood, and A4 paper), monitored the RGB (Red, Green, and Blue) values per pixel of the bloodstain picture at 6-h intervals, and estimated the approximate age of the bloodstain using a smartphone application. The RGB values were converted into the V value of HSV (hue, saturation, and brightness). A rapid decline in RGB and V values was observed over the first 42h and thereafter remained relatively unchanged. The age of the bloodstain could be calculated from the plot of V vs. time. This method enables the estimation of the age of the bloodstain if it is less than 42h old. We will be continuing to work toward optimizing the method, so that the age of the bloodstain older than 42h can be determined using the <I>Smart Forensic Phone</I>. Our detection system offers a novel method to both criminal investigators and researchers for predicting the time elapsed after the victim’s death, which is also called postmortem interval (PMI) or the approximate time when the crime was committed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The system for estimating age of a bloodstain, <I>Smart Forensic Phone</I>, was introduced. </LI> <LI> Time span of a bloodstain was accurately estimated in the various conditions. </LI> <LI> Deoxygenated hemoglobin resulted in light red color of the bloodstain to dark red. </LI> </UL> </P>

Smart Fatigue Phone: Real-time estimation of driver fatigue using smartphone-based cortisol detection

Shin, Joonchul,Kim, Soocheol,Yoon, Taehee,Joo, Chulmin,Jung, Hyo-Il Elsevier Applied Science 2019 Biosensors & bioelectronics Vol. No.

<P><B>Abstract</B></P> <P>Numerous studies reported that psychological fatigue is one of the main reasons leading fatal road crashes. In order to quantify fatigue level of each subject, we measured a concentration of salivary cortisol from 4 subjects (20–40 years of age) using the <I>Smart Fatigue Phone</I>, which consists of a lateral flow immunosensor and a smartphone-linked fluorescence signal reader, during 50-min driving session. Since the salivary cortisol needs to be measured below 1 ng/mL to distinguish the subjects from awaken-drivers, we have employed the fluorescence detection module (Limit of detection: 0.1 ng/mL). To validate correlation between fatigue status and salivary cortisol concentration measured by the <I>Smart Fatigue Phone</I>, the electroencephalogram (EEG) signal was simultaneously obtained from the participants. As a result, alpha wave and concentration of cortisol over time was highly correlated, reflecting that quantification of salivary cortisol can be used for real-time monitoring of driver fatigue (p < 0.05). The <I>Smart Fatigue Phone</I> is expected to be a useful tool for drivers to recognize their fatigue status and subsequently to make a decision for driving a car. Thus, we assume that this fatigue detection system will consequently minimize road crashes by quantifying salivary cortisol in real time in the near future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A smartphone-based cortisol detection was introduced to estimate driver fatigue. </LI> <LI> The low detection limit of 0.1 ng/mL toward salivary cortisol could be achieved. </LI> <LI> The fatigue detection system was validated by measuring EEG with salivary cortisol. </LI> <LI> The high correlation between salivary cortisol and fatigue status was observed. </LI> </UL> </P>

Low-Resistivity Sputtered Films of Transparent Conducting Ta-Doped In2O3 Oxide

Joonchul Moon,Honglyoul Ju,Chang-Oh Jeong,Changwoo Park,강광선,Seung-Han Park,Yungsu Shin 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1

Low-resistivity Ta-doped In2O3 (InTaO) films were grown on Corning1737 glass substrates from a ceramic target of (In0.95Ta0.05)2O3 by radio-frequency magnetron sputtering. The electrical and the optical properties of these films were investigated by varying the oxygen partial pressure pO2 (0 Torr pO2 1.0 × 10−4 Torr) and the deposition temperature TS (25C TS 350 C) during the deposition. The film grown at 350 C and pO2 = 0 Torr showed a resistivity as low as 0.28 m cm with a carrier density of 7.4 × 1020 cm−3, a Hall mobility of 30.1 cm2V−1s−1, an optical band gap of 4.04 eV, and an average transmittance above 85 % for wavelengths between 400 and 700 nm. These values are comparable to those of optimized Sn-doped In2O3 (ITO).

Growth and Electrical Properties of Vanadium-Dioxide Thin Films Fabricated by Magnetron Sputtering

Yungsu Shin,주홍렬,Changwoo Park,Joonchul Moon 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.6

Single crystalline vanadium-dioxide (VO₂) thin films on sapphire (0001) have been grown by using a radio-frequency (rf) magnetron sputtering technique. The dependences of the resistivity change and the hysteresis width of the VO₂ thin films on the oxygen flow ratio [수식] at a fixed deposition temperature of 550℃ have been studied. The VO$_2$ film grown at an oxygen flow ratio of 3.85 % showed a metal-to-insulator transition around ~65℃ with a resistivity ratio as high as 4.3 x 10³ and a hysteresis width of ~6 ℃. Moreover, the VO₂ film, thermally cycled of up to 100 times across the transition temperature, was found to be stable; i.e., no noticeable changes in the magnitude of the resistivity and in the shape of the hysteresis curve were observed. Single crystalline vanadium-dioxide (VO₂) thin films on sapphire (0001) have been grown by using a radio-frequency (rf) magnetron sputtering technique. The dependences of the resistivity change and the hysteresis width of the VO₂ thin films on the oxygen flow ratio [수식] at a fixed deposition temperature of 550℃ have been studied. The VO$_2$ film grown at an oxygen flow ratio of 3.85 % showed a metal-to-insulator transition around ~65℃ with a resistivity ratio as high as 4.3 x 10³ and a hysteresis width of ~6 ℃. Moreover, the VO₂ film, thermally cycled of up to 100 times across the transition temperature, was found to be stable; i.e., no noticeable changes in the magnitude of the resistivity and in the shape of the hysteresis curve were observed.

Highly sensitive and accurate estimation of bloodstain age using smartphone

Choi, Wooseok,Shin, Joonchul,Hyun, Kyung-A,Song, Jaewoo,Jung, Hyo-Il Elsevier 2019 Biosensors & Bioelectronics Vol.130 No.-

<P><B>Abstract</B></P> <P>The estimation of bloodstain age is an important factor in forensic analysis. Previously, we have reported a smartphone-based colorimetric system for age estimation of bloodstain, in which Whole blood and EDTA whole blood were dropped on 4 different materials (700 μL) and captured using a smartphone for 72 h. In order to enhance sensitivity and accuracy of the previous system, the current work is dedicated towards the application of pattern recognition and classification of bloodstain images based on a smartphone. Three detection methods (blood pool, crack ratio, and colorimetric analysis) in terms of 6 steps of drying process of the bloodstain (coagulation, gelation, edge desiccation, center desiccation, crack propagation, and final desiccation) were applied to estimate age of the bloodstain accurately. Three parameters from the bloodstain images were then classified as comparing to those of stored reference images with similar trends in database. The bloodstain age was successfully determined by 9 h, 18 h, and 48 h with respect to the three detection methods mentioned above, respectively. The differences in bloodstain images were clearly distinguished every hour by using smartphone-based pattern recognition analysis. Therefore, our system is expected to shed a light on the field of forensic science by estimating bloodstain age in real time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A smartphone-based pattern recognition was introduced to estimate bloodstain age. </LI> <LI> Blood pool, crack ratio, and brightness values of the images were successfully measured. </LI> <LI> The proposed methods was designed for enhancing accuracy in the early time zone. </LI> <LI> A low detection limit of 1 h toward age estimation of bloodstains could be achieved. </LI> </UL> </P>

Cutting-edge Piezo/Triboelectric-based Wearable Physical Sensor Platforms

Park, Jiwon,Shin, Joonchul,Hur, Sunghoon,Kang, Chong-Yun,Cho, Kyung-Hoon,Song, Hyun-Cheol The Korean Sensors Society 2022 센서학회지 Vol.31 No.5

With the recent widespread implementation of Internet of Things (IoT) technology driven by Industry 4.0, self-powered sensors for wearable and implantable systems are increasingly gaining attention. Piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), which convert biomechanical energy into electrical energy, can be considered as efficient self-powered sensor platforms. These are energy harvesters that are used as low-power energy sources. However, they can also be used as sensors when an output signal is used to sense any mechanical stimuli. For sensors, collecting high-quality data is important. However, the accuracy of sensing for practical applications is equally important. This paper provides a brief review of the performance advanced by the materials and structures of the latest PENG/TENG-based wearable sensors and intelligent applications applied using artificial intelligence (AI)

Measurement and analysis of stress biomarkers in real-time by thermal biosensor

Jung-Hyun Lee,Joonchul Shin,Chenjie Yi,Suji Choi,Hyo-Il Jung 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

Measurement and Analysis of Stress Biomarkers in Real-time by Thermal Biosensor

( Jung Hyun Lee ),( Joonchul Shin ),( Chenjie Yi ),( Suji Choi ),( Hyo Il Jung ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

Studies showed that major causes for people to commit suicide are stress and depression. Both hormone and enzyme, such as cortisol and alpha amylase, indicate stress whereas C-reactive protein (CRP) functions as a depression and inflammatory marker. In order to pinpoint these biomarkers, our research team used 30 nm of the gold nanoparticles (AuNPs) and Ab-Ag interaction for the photo-thermal effect and the concentration of antigen, respectively. In addition to irradiating the aggregated gold nanoparticles through antigen-antibody reaction with laser at the 532 nm wavelength, we also found out that the surface plasmon variation causes temperature rise. Since the application of the photo-thermal effect to the AuNPs enhances the analytical sensitivity up to a 100-fold improvement in comparison with the visual contrast. As the concentration of antigen andthe amount of conjugation between gold nanoparticles and antibody increased, the temperature also increased when compared with the control.

Highly sensitive paper-based immunoassay using photothermal laser speckle imaging

Song, Seungri,Choi, Seoyeon,Ryu, Suho,Kim, Soocheol,Kim, Tongwha,Shin, Joonchul,Jung, Hyo-Il,Joo, Chulmin Elsevier 2018 Biosensors & bioelectronics Vol.117 No.-

<P><B>Abstract</B></P> <P>Paper-based lateral-flow assay (LFA) is a simple and inexpensive point-of-care device that has become commonplace in medicine, environmental monitoring, and over-the-counter personal use. Some LFAs have demonstrated comparable analytical performance with laboratory-based methods, but the detection limit or sensitivity of most LFAs is significantly inferior to other molecular techniques by 10–100 × . Consequently, LFAs are not viable for the early detection of disease-relevant biomarkers that are present in extremely small amounts in clinical specimens. Herein, we present a simple, cost-effective, and highly sensitive LFA sensor based on photothermal laser speckle imaging (PT-LSI). Under the illumination of a photothermal excitation light, gold nanoparticles (AuNPs), a common signal transduction medium in LFAs, absorb the light energy to produce heat, which subsequently induces modulation of the optical property and thermal deformation of the membrane. We measured these fluctuations through laser speckle imaging to quantify the concentration of AuNP-biomarker complexes. We experimentally demonstrate that the detection limit of our technique is superior to that of colorimetric detector by 68–125 × . The capability of our sensor for highly sensitive detection of disease biomarkers is validated by using U.S. FDA-approved LFA kits for cryptococcal antigens (CrAg).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel optical sensor for paper-based immunoassay is described. </LI> <LI> Exploits high-sensitivity of laser speckle to photothermal optical and mechanical perturbations of LFA membrane. </LI> <LI> Demonstrates 68–125 × improved detection limit compared to colorimetric sensor. </LI> <LI> Simple to operate and implement. </LI> </UL> </P>