정예환 교수

Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report h

Humans have a myriad of sensory receptors in different sense organs that form the five traditionally recognized senses of sight, hearing, smell, taste, and touch. These receptors detect diverse stimuli originating from the world and turn them into brain-interpretable electrical impulses for sensory cognitive processing, enabling us to communicate and socialize. Developments in biologically inspired electronics have led to the demonstration of a wide range of electronic sensors in all five tradit

Abstract Haptic technology involves the use of electrical or mechanical means to stimulate afferent nerves or mechanoreceptors in the skin as the basis for creating sensations of physical touch that can qualitatively expand virtual or augmented reality experiences beyond those supported by visual and auditory cues alone. An emerging direction in this field involves the development of platforms that provide spatiotemporal patterns of sensation to the skin across not only the fingertips, but to an

Cortisol is a steroid hormone that is released from the body in response to stress. Although a moderate level of cortisol secretion can help the body maintain homeostasis, excessive secretion can cause various diseases, such as depression and anxiety. Conventional methods for cortisol measurement undergo procedures that limit continuous monitoring, typically collecting samples of bodily fluids, followed by separate analysis in a laboratory setting that takes several hours. Thus, recent studies d

The rapid pace of progress in implantable electronics driven by novel technology has created devices with unconventional designs and features to reduce invasiveness and establish new sensing and stimulating techniques. Among the designs, injectable forms of biomedical electronics are explored for accurate and safe targeting of deep-seated body organs. Here, the classes of biomedical electronics and tools that have high aspect ratio structures designed to be injected or inserted into internal org

Blinding disorders of the outer retina involve dysfunction and degeneration of photoreceptors. One potential approach to treat these forms of blindness is to repopulate the outer retina via a simple bolus injection of donor photoreceptors. However, this may not be ideal due to the highly polarized organization of photoreceptors that include apical light sensing photopigments and basal axon terminals. Furthermore, bolus injections create uncertainty with regard to the area, density, and retention

This letter presents a compact planar flexible antenna designed for wireless local area network (WLAN) using simple microfabrication techniques that are compatible with existing state-of-the-art flexible electronic devices. The antenna is fully insulated with biocompatible Parylene C film, which shows a cost-effective and highly feasible approach to making flexible antennas for implantable applications. Coating of ultrathin Parylene C film has shown negligible effects on the return loss and the

Electronic systems built on flexible plastic films and stretchable rubber sheets have attracted new applications in many emerging fields. Integration of high-speed electronics such as microwave power amplifiers and switches can extend the applications even further with wireless capabilities. As such, flexible and stretchable microwave electronics represent opportunities for future electronics where remote capabilities are desired. Here, we review advances in numerous types of microelectronic dev

Stretchable electrical interconnects based on serpentines combined with elastic materials are utilized in various classes of wearable electronics. However, such interconnects are primarily for direct current or low‐frequency signals and incompatible with microwave electronics that enable wireless communication. In this paper, design and fabrication procedures are described for stretchable transmission line capable of delivering microwave signals. The stretchable transmission line has twisted‐pai

Sensations of heat and touch produced by receptors in the skin are of essential importance for perceptions of the physical environment, with a particularly powerful role in interpersonal interactions. Advances in technologies for replicating these sensations in a programmable manner have the potential not only to enhance virtual/augmented reality environments but they also hold promise in medical applications for individuals with amputations or impaired sensory function. Engineering challenges a

From large industrial computers to non-portable home appliances and finally to light-weight portable gadgets, the rapid evolution of electronics has facilitated our daily pursuits and increased our life comforts. However, these rapid advances have led to a significant decrease in the lifetime of consumer electronics. The serious environmental threat that comes from electronic waste not only involves materials like plastics and heavy metals, but also includes toxic materials like mercury, cadmium

Abstract Novel strategies for printed electronic devices have rapidly evolved, particularly using thin films of inorganic semiconductors for high‐performance. As one of the basic electronic components, diodes provide important functionalities in circuits, such as high‐frequency switching and rectifying. In this report, the fabrication of releasable radio frequency (RF) gallium arsenide (GaAs)‐based Schottky diodes is presented. This technique yields thousands of fully formed diodes with uniform

Skin-Integrated Vibrohaptic Interfaces Haptic technologies add a sense of touch to visual and auditory queues, as the basis for advanced forms of virtual and augmented reality experiences. In article number 2008805, John A. Rogers, Yei Hwan Jung, and Jae-Hwan Kim present the recent progress in flexible, skin-integrated haptic interfaces that enable rapid, spatiotemporally programmed perceptions of touch, with an emphasis on emerging thin, flexible devices that can be gently laminated onto the sk