Yon Kyu Park

MoS2-Based Tactile Sensor for Electronic Skin Applications

A conformal tactile sensor based on MoS2 and graphene is demonstrated. The MoS2 tactile sensor exhibits excellent sensitivity, high uniformity, and good repeatability in terms of various strains. In addition, the outstanding flexibility enables the MoS2 strain tactile sensor to be realized conformally on a finger tip. The MoS2 -based tactile sensor can be utilized for wearable electronics, such as electronic skin.

Quantum-based mechanical force realization in piconewton range

Mechanical force realization based on flux quantization in the piconewton range is proposed. By controlling the number of flux quantum in a superconducting annulus, a force can be created as integer multiples of a constant step. For a 50nm thick Nb annulus with inner and outer radii of 5 and 10μm, respectively, and field gradient of 10T∕m, the force step is estimated to be 184fN. The stability against thermal fluctuations is also addressed.

Si membrane based tactile sensor with active matrix circuitry for artificial skin applications

The fabrication and the characteristics of an inorganic silicon-based flexible tactile sensor equipped with active-matrix circuitry compatible with a batch microfabrication process are reported. An 8 × 8 array of 260 nm-thick silicon strain gauges along with individual thin film transistor switches was built on a plastic substrate with 1 mm spacing, corresponding to a human spatial resolution at the fingertip. We demonstrated that the sensor shows excellent performances in terms of repeatability of 1.1%, hysteresis of 1.0%, scanning speed of as much as 100 kHz and resolution of 12.4 kPa while maintaining low power consumption and signal crosstalk through a series of experiments.

Quantitative Sasang Constitution Diagnosis Method for Distinguishing between Tae-eumin and Soeumin Types Based on Elasticity Measurements of the Skin of the Human Hand

The usefulness of constitutional diagnoses based on skin measurements has been established in oriental medicine. However, it is very difficult to standardize traditional diagnosis methods. According to Sasang constitutional medicine, humans can be distinguished based on properties of the skin, including its texture, roughness, hardness and elasticity. The elasticity of the skin was previously used to distinguish between people with Tae-eumin (TE) and Soeumin (SE) constitutions. The present study designed a system that uses a compression method to measure the elasticity of hand skin and evaluated its measurement repeatability. The proposed system was used to compare the skin elasticity between SE and TE subjects, which produced a measurement repeatability error of <3%. The proposed system is suitable for use as a quantitative constitution diagnosis method for distinguishing between TE and SE subjects with an acceptable level of uncertainty.

The development of a blood pressure simulator in KRISS

Blood pressure is defined as the amount of force at unit area which the blood exerts on a wall of a blood vessel. The BP has a clinical importance as the basic index in the medical examination of patients. Especially, the percentage of the hypertensive is more than 15% in an adult population of Korea and hypertension is notorious as ‘a silent killer’ because it has no prior symptoms. The most important thing in the diagnosis, treatment and prognosis of hypertension is the accurate measurement of the BP. In this study, we developed the blood pressure simulator for the monitoring of oscillometric BP devices and compared this KRISS simulator with commercial simulators. Finally, we tested the commercial oscillometric BP devices (6 models from 5 manufacturers) using the KRISS simulator. The KRISS simulator has the repeatability error below 0.1% for the pressure generation and we expected to develop the BP simulator for Korean by the collection of clinical data from Koreans.

The development of the friction coefficient inspection equipment for skin using a load cell

The skin is an indispensible organ for human because it contributes to the metabolism using its own biochemical functions as well as it protects the human body from the exterior stimuli. Recently, the friction coefficient have been used as the decision index of the progress for the bacterial aliments in the field of the skin physiology and the importance of friction coefficient have been increased in the skin care market because of the needs of the well being times. In addition, the usage of friction coefficient is known to have the big discrimination ability in classification of human constitutions, which is utilized in the alternative medicine. In this study, we designed a system which used the multi axes load cell and hemi-circular probe and tried to measure the friction coefficient of hand skins repeatedly. Using this system, the relative repeatability error for the measurement of the friction coefficient was below 4 %. The coefficient is not concerned in curvatures of tips. Using this system, we will try to establish the standard for classification of constitutions.

Dynamic Bridge Structure Monitoring Using Smart Elastomeric Bearing Equipped with PVDF Polymer Film

A smart elastomeric bearing using PVDF polymer film, which is very sensitive to dynamic loading condition, was developed. The PVDF polymer film was inserted into the elastomeric bearing to monitor the normal or shear load of the bridge structure. Thus, the prototype of the smart elastomeric bearing was finally fabricated with the electric circuit for signal of the PVDF polymer film to use as a monitoring system of the bridge structure. The evaluation apparatus of the smart elastomeric bearing was manufactured with shake and steel plate corresponding to bridge. The bearing was installed at the fabricated miniature bridge structure and tested under a variety of dynamic conditions. Finally the system confirmed that real time measurement of the elastomeric bearing in the bridge provided the structure with certain intelligence.