• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.133-138
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• 2019

The a-InGaZnO (a-IGZO) thin film transistor (TFT) has the advantages of larger mobility than that of amorphous silicon TFTs, acceptable reliability and uniformity over a large area, and low process cost. A capacitive-type touch sensor was studied with an a-IGZO TFT that can be used on the front side of a display due to its transparency. A capacitive sensor detects changes of capacitance between the surface of the finger and the sensor electrode. The capacitance varies according to the distance between the sensor plate and the touching or non-touching of the sensing electrode. A capacitive touch sensor using only one a-IGZO TFT was developed with the reduction of two bus lines, which made it easy to reduce the pixel pitch. The proposed sensor circuit maintained the amplification performance, which was investigated for various drive conditions.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.7
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• pp.870-874
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• 2005

This paper presents capacitive tactile sensor that can detect normal and shear forces. This tactile sensor consists of index plate, sensing plate, and elastic dielectric layer. The calculated sensing character is based on the changes of space between two horizontal plate. Larger overlap areas and narrow space between top and bottom plate guarantees higher sensitivity. Tactile sense information can be calculated from the changes of phase of output signal. The symmetric arrangement of sensing plates makes the manufacturing process easier and guarantees the stability of the structure. In this paper, the sensor structure is designed, the mechanism of the Proposed sensor is theoretically explained, and the simulated result is presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1109-1112
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• 2004

This paper presents a high sensitive force sensing module to measure machining forces for a tip-based nanopatterning instrument. The force sensing module utilizing a leaf spring mechanism and a capacitive displacement sensor has been designed to provide a measuring range from 80$\mu$N to 8N. This force sensing module is mounted on a PZT driven in-feed motion stage with 1 nm resolution. The sample can be moved by a X-Y scanning motion stage with 5 nm resolution. In the patterning experiments, the machining forces were controlled and monitored by the force sensing module. Then, the patterned sample was measured by AFM. Experimental results demonstrated that the developed force sensing module can be used as an effective sensing device in the nanopatterning operation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.387-393
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• 2004

General purpose of cylindrical capacitive displacement sensor(CCS) is measuring run-out motion and deflection of rotor. If CCS has narrow sensing range, its sensitivity coefficients must be calibrated precisely. And x, y component of CCS output can be coupled. In this research, CCS calibration procedure is automated with automatic calibration program and PC-controlled stage. And, coupled-terms of CCS signals were removed and the errors between measured position and mapped CCS signal were reduced obviously by sensitivity matrix that linearly.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.391-395
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• 2002

This paper described about the ultra-precision profile measurement of aspheric surfaces using contact probing technique. A contact probe has been designed as a sensing device to obtain measuring resolutions in nanometer regime utilizing a leaf spring mechanism and a capacitive-type sensor. The contact probe is attached on the z-axis during measurement while aspheric objects are supported on the single point diamond turning machine(SPDTM). The machine xz-axis motions are monitored by a set of two orthogonal plane mirror type laser interferometers. Experimental results show that the contact probing technique developed of On-machine Measurement System in this investigation is capable of providing a repeatability of 20 nanometers with a $\pm$20 uncertainty of 300 nanometers.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.65-70
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• 2008

Capacitive position sensing with modulation technique is widely used in electrostatic actuator applications. To maximize the electrostatic force and the position-sensing gain, capacitors for driving and capacitors for sensing are shared, i.e, after applying the driving voltage with high-frequency modulating signals using op amps, the position is demodulated from the modulated signal. In high-voltage applications, however, low bandwidth of a high-voltage op amp hinders adding the high-frequency modulating signal to the driving voltage. In this paper, new and very simple driving and sensing method is proposed, in which the pulse-width modulated driving voltage eliminates the need of the high-frequency modulating signal for position sensing. This new algorithm is proved by the simulation results using Matlab/SIMULINK.

• Journal of Sensor Science and Technology
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• v.32 no.1
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• pp.22-30
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• 2023

Innovative and advanced technologies, including robots, augmented reality, virtual reality, the Internet of Things, and wearable medical equipment, have largely emerged as a result of the rapid evolution of modern society. For these applications, pressure monitoring is essential and pressure sensors have attracted considerable interest. To improve the sensor performance, several new designs of pressure sensors have been researched based on resistive, capacitive, piezoelectric, optical, and triboelectric types. In particular, optical pressure sensors have been actively studied owing to their advantages, such as robustness to noise and remote sensing capability. Herein, a review of recent research on optical pressure sensors with self-powered sensing, remote sensing, high spatial resolution, and multimodal sensing capabilities is presented from the viewpoints of design, fabrication, and signal processing.

• 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.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.62-65
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• 2019

Wireless power transfer systems require an algorithm to determine the presence of the target object for mitigating standby power and safety issues. Although many schemes that sense various external objects have been actively proposed for inductive power transfer systems, not many studies on capacitive power transfer systems have been conducted compared with those on inductive power transfer systems. This study proposes a target object detection algorithm by monitoring the capacitance in transmitter-side electrodes without additional pressure sensors or distance sensors. The proposed algorithm determines the presence of a target object by monitoring the change in capacitance in transmitter-side electrodes using the step pulse of the microcontroller unit. The algorithm is verified by two step processes. First, the performance in capacitance measurement is compared with that of an LCR meter. Then, the verification is conducted in a 5-W capacitive power transfer hardware. Experimental result shows that the interelectrode capacitance increases by 6 times when the target object is fully aligned. Thus, the proposed scheme can successfully detect the presence of the target object.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.42-50
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• 2005

This paper presents an ultra precision machining system using a high sensitive force sensing module to measure machining forces and penetration displacement in a tip-based nanopatterning. The force sensing module utilizes a leaf spring mechanism and a capacitive displacement sensor and it has been designed to provide a measuring range from 80 ${\mu}N$ to 8 N. This force sensing module is mounted on a PZT driven in-feed motion stage with 1 nm resolution. The sample can be moved by X-Y scanning motion stage with 5 nm resolution. In nano indentation experiments and patterning experiments, the machining forces were controlled and monitored by the force sensing module. Then, the patterned samples were measured by AFM. Experimental results demonstrated that the developed system can be used as an effective device in nano indentation and nanopatterning operation.