변영재 교수

Recent advances in wearable electronics combined with wireless communications are essential to the realization of medical applications through health monitoring technologies. For example, a smart contact lens, which is capable of monitoring the physiological information of the eye and tear fluid, could provide real-time, noninvasive medical diagnostics. However, previous reports concerning the smart contact lens have indicated that opaque and brittle components have been used to enable the opera

We developed a transparent and flexible, capacitive fingerprint sensor array with multiplexed, simultaneous detection of tactile pressure and finger skin temperature for mobile smart devices. In our approach, networks of hybrid nanostructures using ultra-long metal nanofibers and finer nanowires were formed as transparent, flexible electrodes of a multifunctional sensor array. These sensors exhibited excellent optoelectronic properties and outstanding reliability against mechanical bending. This

Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materi

We introduce a new type of multi-functional capacitive sensor that can sense several different external stimuli. It is fabricated only with polydimethylsiloxane (PDMS) films and silver nanowire electrodes by using selective oxygen plasma treatment method without photolithography and etching processes. Differently from the conventional single-capacitor multi-functional sensors, our new multi-functional sensor is composed of two vertically-stacked capacitors (dual-capacitor). The unique dual-capac

Continuous glucose monitoring systems (CGMS) are becoming increasingly popular in diabetes management compared to conventional methods of self-blood glucose monitoring systems. They help understanding physiological responses towards nutrition intake, physical activities in everyday life and glucose control. CGMS available in market are of two types based on their working principle. Needle type systems with few weeks lifespan (e.g., enzyme-based Freestyle Libre) and implant type system (e.g., flu

Limitations in data transmission caused by band limitation in broadband communication links can be improved significantly by using equalization techniques. In this paper, a reconfigurable feed-forward equalizer employing a transition detector (TD)-based calibration technique that provides a universal channel compensation solution is presented. Moreover, the newly proposed TD-based calibration technique monitors the channel output for further adjustments over time in order to provide optimum comp

In the present work, we demonstrate controlling the excitation of bright mode (continuum mode) resonance and dark mode (discrete mode) resonance in a planar metasurface made of sinusoidal modulation inside a closed rectangular metallic ring placed over a dielectric substrate. Unlike asymmetrical breaking of a meta-atom (often referred to as the unit cell) to achieve the dark mode response in regular metamaterials, in the present structure, the bright or dark mode resonance is achieved using even

An algorithm for a capacitive touch screen panel that can make the sum of the signal into ‘0’ for the use of high voltage is presented. The differential Manchester code is combined with the Walsh‐Hadamard code to generate an input coded signal. Owing to the property of the differential Manchester code, the Moore‐Penrose pseudoinverse matrix is employed to decode‐mutual capacitance from the received signal. As only the variation between the un‐touch and touch condition is detected at the receiver

Research on magnetically resonant wireless power transfer (MRWPT) is actively pursued for diverse applications. Dependent on magnetic fields for wireless power transfer (WPT), MRWPT encounters a challenge due to the absence of monopole magnetic properties, impacting power transfer efficiency (PTE) sensitivity to receiver arrangement. Despite extensive research, achieving the desired receiver freedom remains a persistent challenge-a core limitation rooted in magnetic field-based WPT. To address t

In wireless power transfer technology, power control technique is required to realise constant current (CC) and constant voltage (CV) modes for battery charging. CC and CV modes are needed to effectively charge lithium (Li)‐ion batteries to ensure long life span and maximum capacity utilisation. The use of additional battery charging circuitry reduces efficiency, increases volume, and increases circuit complexity. The frequency modulation method is a method that can control power without an addi

Despite coronavirus disease 2019, cardiovascular disease, the leading cause of global death, requires timely detection and treatment for a high survival rate, underscoring the 24 h monitoring of vital signs. Therefore, telehealth using wearable devices with vital sign sensors is not only a fundamental response against the pandemic but a solution to provide prompt healthcare for the patients in remote sites. Former technologies which measured a couple of vital signs had features that disturbed pr

Recently, research has been actively conducted to overcome various challenges observed in wireless power transfer (WPT) technology. However, as additional techniques are implemented, the complexity and cost of WPT systems increased. Therefore, there is a need for a new WPT method that can overcome the shortcomings of existing technology. This paper presents a metal surface guided-wireless power transfer (MSG-WPT) system for applications with multiple receivers (Rxs). First, a plate-wire propagat

A waveform generator for a 77 GHz automotive radar that uses multiple frequency shift keying (MFSK) modulation is presented. The use of this modulation can improve the detection ability of radar applications in multi‐target situations. The proposed generator consists of a conventional 77 GHz Σ‐Δ fractional‐N synthesiser and MFSK modulation control logic (MMCL). The key innovation is the introduction of the MMCL, which has the ability to track the linear frequency increase while generating the fr

Obstructive sleep apnea (OSA) is common among older populations and individuals with cardiovascular diseases. OSA diagnosis is primarily conducted using polysomnography or recommended home sleep apnea test (HSAT) devices. Wireless wearable devices have emerged as promising tools for OSA screening and follow-up. This study introduces a novel automated algorithm for detecting OSA using abdominal movement signals and acceleration data collected by a wireless abdomen-worn sensor (Soomirang). Thirty-

The adoption of mobile robots in industrial automation is rapidly expanding, driven by not only economic advantages but also considerations for environmental conservation and worker safety. Dynamic wireless power transfer systems for mobile logistics robots emerge as a promising technology, enhancing the feasibility of battery-less mobile robots while concurrently reducing energy and raw material consumptions associated with battery production. Recent research in track-powered mobile robots has