• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.403-410
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• 2022

Flexible and wearable sensing technologies have emerged as a result of developments in interdisciplinary research across several fields, bringing together various subjects such as biology, physics, chemistry, and information technology. Moreover, various types of flexible wearable biocompatible devices, such customized medical equipment, soft robotics, bio-batteries, and electronic skin patches, have been developed over the last several years that are extensively employed to monitor biological signals. As a result, we present an updated overview of new bio-implantable sensor technologies for various applications and a brief review of the state-of-the-art technologies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.764-770
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• 2014

It is expected that the techniques of optical imaging through turbid media enables non-invasive imaging through human skin and biological tissues. In recent years, many researches have shown that imaging through turbid media can be made possible by measuring the transmission matrix (TM) of the turbid medium and utilizing it for image recovery. However, this TM based image recovery requires a huge amount of data acquisition and post signal processing of them. Very recently, there were new results that this problem of huge data acquisition and processing can be resolved by using the compressed sensing (CS) framework. CS is a relatively new signal acquisition and reconstruction framework which makes possible to recover the signal of interest correctly with significantly smaller number of signal measurements. In this paper, the TM-based image recovery in imaging through turbid media is reviewed and the recent progress made by using CS is introduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.1-11
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• 2016

The information about the deformations of high-aspect-ratio wings is needed for the real-time monitoring of structural responses. Wing deformation in flight can be predicted by using relationship between the curvatures and the strains on the wing skin. It is also necessary to consider geometric nonlinearity when the large deformation of wing is occurred. The strain distribution on fixed-end is complex in the chordwise direction because of the geometric shape of fixed-wings on fuselages. Hence, the wing displacement can be diversely predicted by the location of the strain sensing lines in the chordwise direction. We conducted a study about prediction method of displacements regardless of the chordwise strain sensing locations. To correct spanwise strains, the ratio of spanwise strain to chordwise strain, Poisson's ratio, and the ratio of the plate strain to the beam strain were used. The predicted displacements using the strain correction were consistent with those calculated by the FEA and verified through the bending testing.

• Korean Journal of Acupuncture
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• v.28 no.3
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• pp.63-71
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• 2011

Objectives : The aim of this study is to develop the system and evaluate the optical analytical technique that reflects acupoint pigmentation and extravasated blood by cupping. Methods : We designed the system able to express XYZ coordinate on local skin color. To evaluate measurement-accuracy, we compared with 24 Color Checker Chart by standardized Commission Internationale de l'Eclairage. After confirming the performance of system, we experimented with cupping which was 80 kPa negative pressure for 1 minute on left/right BL13. The X, Y and Z values were converted to R, G and B, $L^*$, $a^*$ and $b^*$, Erythema Index (E.I.), and Melanin Index (M.I). We compared and analyzed two cases on before/after cupping. Results : The R, G and B values which were converted by X, Y and Z values had high linearity as a high level of R-square (R: 0.969, G: 0.996, and B: 0.992). Moreover, we confirmed that it was possible to quantitatively analyzed the change in skin color by cupping using R, G, B, $L^*$, $a^*$, $b^*$, E.I., and M.I. Conclusions : Therefore, we proposed the new analytical technique for objectifying the oriental medical diagnostic method using cupping and optical sensing technique.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.4
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• pp.300-308
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• 2010

This paper describes the development of a low-power electrocardiogram (ECG) touch sensor intended for the use with two dry metal electrodes. An equivalent ECG extraction circuit model encountered in a ground-free two-electrode configuration is investigated for an optimal sensor read-out circuit design criteria. From the equivalent circuit model, (1) maximum sensor resolution is derived based on the electrode's background thermal noise, which originates from high electrode-skin contact impedance, together with the input referred noise of instrumentation amplifier (IA), (2) 60 Hz electrostatic coupling from mains and motion artifact are also considered to determine minimum requirement of common mode rejection ratio (CMRR) and input impedance of IA. A dedicated ECG read-out front end incorporating chopping scheme is introduced to provide an input referred circuit noise of 1.3 ${\mu}V_{rms}$ over 0.5 Hz ~ 200 Hz, CMRR of IA > 100 dB, sensor resolution of 7 bits, and dissipating only 36 ${\mu}W$. Together with 8 bits synchronous successive approximation register (SAR) ADC, the sensor IC chip is implemented in 0.18 ${\mu}m$ CMOS technology and integrated on a 5 cm $\times$ 8 cm PCB with two copper patterned electrodes. With the help of proposed touch sensor, ECG signal containing QRS complex and P, T waves are successfully extracted by simply touching the electrodes with two thumbs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.214-221
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• 2007

This paper presents a myoelectric hand prosthesis(MHP) with two degree of freedom(2-DOF), which consists of a mechanical hand, a surface myoelectric sensor(SMES) for measuring myoelectric signal, a control system and a charging battery. The actuation for the 2-DOF hand functions such as grasping and wrist rotation was performed by two DC-motors, and controlled by myoelectric signal measured from the residual forearm muscle. The grip force of the MHP was automatically changed by a mechanical automatic speed reducer mounted on the hand. The skin interface of SMES was composed of the electrodes using the SUS440 metal in order to endure a wet condition due to the sweat. The sensor was embedded with a amplifier and a filter circuit for rejecting the offset voltage caused by power line noises. The control system was composed of the grip force sensor, the slip sensor, and the two controllers. The two controllers were made of a RISC-type microprocessor, and its software was executed on a real-time kernel. The control system used Force Sensing Resistors, FSR, as slip pick-ups at the fingertip of a thumb and the grip force information was obtained from a strain-gauge on the lever of the MHP. The experimental results were showed that the proposed control system is feasible for the MHP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.992-999
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• 2009

The pulse transit time(PTT), which is determined by measuring the electrocardiogram(ECG) and pulse wave, gives comprehensive information about the cardiovascular system. However, a little movement of body and/or inaccurate pressure applied to skin during the measurement of pulse wave leads to acquire incorrect results. To overcome such problem, we developed an integrated sensor system which makes it possible to measure ECG, pressure pulse wave(PPW) and photoplethysmograph(PPG) at the same time. Futhermore, we implemented a new metal electrode which enables to continuously measure ECG. We verified that both integrated sensor system and new electrode provide useful effect.

• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.42-45
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• 2015

The ability to take electrocardiographic measurements while performing our daily activities has become the people-choice for modern age vital sign sensing. Currently, wet and dry ECG electrodes are known to pose threats like inflammations, allergic reactions, and metal poisoning due to their direct skin interaction. Therefore, the main goal in this work is to implement a very small ECG sensor system with a capacitive coupling, which is able to detect electrical signals of heart at a distance without the conductive gel. The aim of this paper is to design, implement, and characterize the contactless ECG electrodes. Under a careful consideration of factors that affect a capacitive electrode functional integrity, several different sizes of ECG electrodes were designed and tested with a pilot ECG device. A very small cotton-insulated copper tape electrode ($2.324cm^2$) was finally attained that could detect and measure bioelectric signal at about 500 um of distance from the subject's chest.

• Journal of Fashion Business
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• v.21 no.2
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• pp.78-90
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• 2017

In this study, brassiere prototype was developed for attaching the measuring module of ECG measurement and body movement while sleeping. For ECG measurement, textile electrodes was made of stretch fabric containing polyurethane in consideration of elasticity of brassiere band. It was used as a conductive yarn by silver coating on the warp. The textile electrodes was woven with twisted twill to increase the density of conductive yarns. The pressure of the brassiere band was enough to sensing stably the ECG, and the elastic band of the brassiere was designed to be wider than 3cm to install the textile electrodes inside, so that textile electrodes was close fitting to the skin at a constant pressure without lifting. The textile electrodes coated with silicon on rear was attached to brassiere elastic band, and the module was installed with a snap connector to textile electrodes of brassiere band. The module was suitable to monitering ECG measurement of a typical R peak, pulse rate and body movement while sleeping without interfering.