Jong-Baek Park

In human fingertips, the fingerprint patterns and interlocked epidermal-dermal microridges play a critical role in amplifying and transferring tactile signals to various mechanoreceptors, enabling spatiotemporal perception of various static and dynamic tactile signals. Inspired by the structure and functions of the human fingertip, we fabricated fingerprint-like patterns and interlocked microstructures in ferroelectric films, which can enhance the piezoelectric, pyroelectric, and piezoresistive

The development of flexible electronic skins with high sensitivities and multimodal sensing capabilities is of great interest for applications ranging from human healthcare monitoring to robotic skins to prosthetic limbs. Although piezoresistive composite elastomers have shown great promise in this area of research, typically poor sensitivities and low response times, as well as signal drifts with temperature, have prevented further development of these materials in electronic skin applications.

Stretchable electronic skins with multidirectional force-sensing capabilities are of great importance in robotics, prosthetics, and rehabilitation devices. Inspired by the interlocked microstructures found in epidermal-dermal ridges in human skin, piezoresistive interlocked microdome arrays are employed for stress-direction-sensitive, stretchable electronic skins. Here we show that these arrays possess highly sensitive detection capability of various mechanical stimuli including normal, shear, s

Haptic human-machine interfaces (HHMIs) combine tactile sensation and haptic feedback to allow humans to interact closely with machines and robots, providing immersive experiences and convenient lifestyles. Significant progress has been made in developing wearable sensors that accurately detect physical and electrophysiological stimuli with improved softness, functionality, reliability, and selectivity. In addition, soft actuating systems have been developed to provide high-quality haptic feedba

Biological tissues are multiresponsive and functional, and similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic polymers have applications in force-responsive colorimetric sensors and soft robotics, but their integration into sensitive, multifunctional devices remains challenging. Herein, a hierarchical nanoparticle-in-micropore (NP-MP) architecture in porous mechanochromic polymers, which enhan

Flexible electronic devices are regarded as one of the key technologies in wearable healthcare systems, wireless communications and smart personal electronics. For the realization of these applications, wearable energy and sensor devices are the two main technologies that need to be developed into lightweight, miniaturized, and flexible forms. In this review, we introduce recent advances in the controlled design of device structures into bioinspired micro/nanostructures and 2D/3D structures for

Accurate transmission of biosignals without interference of surrounding noises is a key factor for the realization of human-machine interfaces (HMIs). We propose frequency-selective acoustic and haptic sensors for dual-mode HMIs based on triboelectric sensors with hierarchical macrodome/micropore/nanoparticle structure of ferroelectric composites. Our sensor shows a high sensitivity and linearity under a wide range of dynamic pressures and resonance frequency, which enables high acoustic frequen

Transfer printing of electronic functions on arbitrary surfaces is essential for next-generation applications of skin-attachable electronics, wearable sensors, and implantable/medical devices. For transfer printing of electronic functions on multidimensional surfaces, such as curved regions of the skin and different objects, various strategies have been devised based on the materials and structural design of electronic components and transfer stamps, such as ultrathin membranes or in-plane struc

Smart speakers, which provide continuous real-time information and convenient services, increasingly permeate into users’ homes. On the other hand, the environments of the smart speaker also cause privacy issues for the users by always listening to users’ voices in their private homes. The privacy-prone environments of the smart speakers lead to the users’ coping behaviors against privacy threats not only by increasing the users’ privacy concerns but also by creating negative emotions. However,

While mobile social network sites (SNSs) function as a platform for social and self-communication that leads to sense of others and oneself, users may feel irritation derived from social interaction and technical frustration in using mobile SNSs. Because of the ubiquitous nature of mobile devices, sense of presence and irritation are more influential to users' satisfaction of mobile SNSs. This study investigates the influence of a sense of presence and irritation on users' satisfaction with mobi