Won Yong Lee

Mechanically flexible active multielectrode arrays (MEA) have been developed for local signal amplification and high spatial resolution. However, their opaqueness limited optical observation and light stimulation during use. Here, we show a transparent, ultraflexible, and active MEA, which consists of transparent organic electrochemical transistors (OECTs) and transparent Au grid wirings. The transparent OECT is made of Au grid electrodes and has shown comparable performance with OECTs with nont

High-precision monitoring of electrophysiological signals with high spatial and temporal resolutions is one of the most important subjects for elucidating physiology functions. Recently, ultraflexible multielectrode arrays (MEAs) have been fabricated to establish conformal contacts with the surface of organs and to measure propagation of electrophysiological signals with high spatial-temporal resolution; however, plastic substrates have high Young's modulus, causing difficulties in creating appr

Integration of organic electrochemical transistors and organic field-effect transistors is successfully realized on a 600 nm thick parylene film toward an electrophysiology array. A single cell of an integrated device and a 2 × 2 electrophysiology array succeed in detecting electromyogram with local stimulation of the motor nerve bundle of a transgenic rat by a laser pulse.

Abstract Skin‐based electrical‐signal monitoring is one of the basic and noninvasive diagnostic methods for observing vital signals that contain valuable information about the dynamic status of the inner body. Soft bioelectronic devices are developed for the acquisition of high‐quality biosignals by taking advantage of their inherent thin and soft bodies. Among these devices, the organic electrochemical transistor (OECT) is a promising local transducing amplifier because of its key advantages, s

Flexible microneedles are important tools that allow access to the inside of biological tissue from the outside without surgery. However, it had been hard to realize microneedle sensor arrays on flexible substrates because of the difficulty of attaining a needle with a high Young’s modulus for a selected area on a thin or soft substrate. In this work, we developed a microneedle sensor on a hybrid substrate based on high Young’s modulus epoxy siloxane for the microneedles and low Young’s modulus

The spatiotemporal bioelectrical signals produced by living bodies play a significant role in enlightening biological functions. In recent years, flexible devices have emerged as a means of monitoring biological information. In order to measure bioelectrical signals using a two-dimensional flexible device, it is necessary to combine a flexible multielectrode array with an active matrix that minimizes the number of wires. It is necessary for the flexible active multielectrode array to possess sev

Abstract Ecoflex is widely used in bioelectronics due to its outstanding properties of low modulus and large stretchability. For its use as an encapsulation layer in multi-channel wearable devices, a patterning procedure is essential. However, conventional patterning strategies for Ecoflex, such as soft lithography, punching, and laser ablation, lack sufficient quality and process compatibility. To address this, we propose a process-compatible method of patterning Ecoflex by developing Photo-pat

Vacuum ultraviolet irradiation is used as a tool to systematically study the morphology, growth, and performance of small-molecule organic field-effect transistors. The surface energy can be carefully and precisely tuned by varying the dose of irradiation, allowing for the systematic study of the growth of an emerging organic semiconductor. This technique helps to methodically control the morphology and performance of organic semiconductors.

Flexible, transparent electrodes are a crucial component for future implantable and wearable systems. For practical applications, conductivity and flexibility should be further improved to prevent signal attenuation, heat generation, and disconnection. Herein, we fabricate an ultraflexible transparent electrode with low sheet resistance (8.6 Ω/sq) using an indium-tin-oxide/Au/indium-tin-oxide (ITO) multilayer on a 1 μm thick parylene substrate. The electrodes were foldable and when compared to p

Photolithography is a well-established fabrication method for realizing multilayer electronic circuits. However, it is challenging to adopt photolithography to fabricate intrinsically stretchable multilayer electronic circuits fully composed of an elastomeric matrix, due to the opacity of thick stretchable nanocomposite conductors. Here, we present photothermal lithography that can pattern elastomeric conductors and via holes using pulsed lasers. The photothermal-patterned stretchable nanocompos

Significance We successfully performed the intracellular action potential recording using organic electrochemical transistors (OECTs). A simultaneous multipoint recording with a 4 × 4 matrix of 5- × 5-μm 2 OECTs demonstrated the feasibility of potential high-resolution recording. The intracellular access was obtained by applying a pulse voltage to the drain electrode, and the amplitude of recorded signal reached 93 µA at maximum. This simple intracellular access method offers a higher signal-to-

Patterning elastomers is an essential process for the application of elastomers to stretchable bioelectric devices. In general, replication of a mold and laser ablation are used for patterning elastomers. However, these methods are inefficient and time consuming due to complex patterning procedures and a heat-induced curing mechanism. In this work, we developed a photopatternable elastomer called thiol-ene cross-linked poly(dimethylsiloxane) (TC-PDMS). TC-PDMS showed high-resolution patternabili

With the rapid development of wearable devices, healthcare technologies that enable an accurate monitoring of electrophysiological signals and provide electrical stimulation for therapy are extensively researched. In this regard, 1D nanomaterials are widely used in bioelectronics owing to their advantageous properties such as transparency, mechanical flexibility, and stretchability. Herein, the recent advances in bioelectronic devices based on 1D nanomaterials are reviewed with a focus on the bi