Wang Jiahui
Email Address
elejiah@nus.edu.sg
Organizational Units
SPECIALTY RESEARCH INST/CTRS
faculty
ENGINEERING
faculty
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Publication Search Results
Now showing 1 - 8 of 8
Publication Self-Sustainable Wearable Textile Nano-Energy Nano-System (NENS) for Next-Generation Healthcare Applications(WILEY, 2019-10-24) He, Tianyiyi; Wang, Hao; Wang, Jiahui; Tian, Xi; Wen, Feng; Shi, Qiongfeng; Ho, John S; Lee, Chengkuo; Assoc Prof Chengkuo Lee; ELECTRICAL AND COMPUTER ENGINEERING; LIFE SCIENCES INSTITUTEWearable electronics presage a future in which healthcare monitoring and rehabilitation are enabled beyond the limitation of hospitals, and self-powered sensors and energy generators are key prerequisites for a self-sustainable wearable system. A triboelectric nanogenerator (TENG) based on textiles can be an optimal option for scavenging low-frequency and irregular waste energy from body motions as a power source for self-sustainable systems. However, the low output of most textile-based TENGs (T-TENGs) has hindered its way toward practical applications. In this work, a facile and universal strategy to enhance the triboelectric output is proposed by integration of a narrow-gap TENG textile with a high-voltage diode and a textile-based switch. The closed-loop current of the diode-enhanced textile-based TENG (D-T-TENG) can be increased by 25 times. The soft, flexible, and thin characteristics of the D-T-TENG enable a moderate output even as it is randomly scrunched. Furthermore, the enhanced current can directly stimulate rat muscle and nerve. In addition, the capability of the D-T-TENG as a practical power source for wearable sensors is demonstrated by powering Bluetooth sensors embedded to clothes for humidity and temperature sensing. Looking forward, the D-T-TENG renders an effective approach toward a self-sustainable wearable textile nano-energy nano-system for next-generation healthcare applications.Publication Toward Bioelectronic Medicine?Neuromodulation of Small Peripheral Nerves Using Flexible Neural Clip(2017) Lee, S; Peh, W.Y.X; Wang, J; Yang, F; Ho, J.S; Thakor, N.V; Yen, S.-C; Lee, C; ELECTRICAL AND COMPUTER ENGINEERING; LIFE SCIENCES INSTITUTENeural modulation technology and the capability to affect organ function have spawned the new field of bioelectronic medicine. Therapeutic interventions depend on wireless bioelectronic neural interfaces that can conformally and easily attach to small (few hundred micrometers) nerves located deep in the body without neural damage. Besides size, factors like flexibility and compliance to attach and adapt to visceral nerves associated moving organs are of paramount importance and have not been previously addressed. This study proposes a novel flexible neural clip (FNC) that can be used to interface with a variety of different peripheral nerves. To illustrate the flexibility of the design, this study stimulates the pelvic nerve, the vagus nerve, and branches of the sciatic nerve and evaluates the feasibility of the design in modulating the function of each of these nerves. It is found that this FNC allows fine-tuning of physiological processes such as micturition, heart rate, and muscle contractions. Furthermore, this study also tests the ability of wirelessly powered FNC to enable remote modulation of visceral pelvic nerves located deep in the body. These results show that the FNC can be used with a range of different nerves, providing one of the critical pieces in the field of bioelectronics medicines. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Publication Investigation of Low-Current Direct Stimulation for Rehabilitation Treatment Related to Muscle Function Loss Using Self-Powered TENG System(WILEY, 2019-07-17) Wang, Jiahui; Wang, Hao; He, Tianyiyi; He, Borong; Thakor, Nitish; Lee, Chengkuo; Assoc Prof Chengkuo Lee; ELECTRICAL AND COMPUTER ENGINEERING; LIFE SCIENCES INSTITUTEMuscle function loss is characterized as abnormal or completely lost muscle capabilities, and it can result from neurological disorders or nerve injuries. The currently available clinical treatment is to electrically stimulate the diseased muscles. Here, a self-powered system of a stacked-layer triboelectric nanogenerator (TENG) and a multiple-channel epimysial electrode to directly stimulate muscles is demonstrated. Then, the two challenges regarding direct TENG muscle stimulation are further investigated. For the first challenge of improving low-current TENG stimulation efficiency, it is found that the optimum stimulation efficiency can be achieved by conducting a systematic mapping with a multiple-channel epimysial electrode. The second challenge is TENG stimulation stability. It is found that the force output generated by TENGs is more stable than using the conventional square wave stimulation and enveloped high frequency stimulation. With modelling and in vivo measurements, it is confirmed that the two factors that account for the stable stimulation using TENGs are the long pulse duration and low current amplitude. The current waveform of TENGs can effectively avoid synchronous motoneuron recruitment at the two stimulation electrodes to reduce force fluctuation. Here, after investigating these two challenges, it is believed that TENG direct muscle stimulation could be used for rehabilitative and therapeutic purpose of muscle function loss treatment.Publication Unveiling Stimulation Secrets of Electrical Excitation of Neural Tissue Using a Circuit Probability Theory(Frontiers Media SA, 2020-07-10) Wang, H; Wang, J; Thow, XY; Lee, S; Peh, WYX; Ng, KA; He, T; Thakor, NV; Lee, C; Assoc Prof Chengkuo Lee; ELECTRICAL AND COMPUTER ENGINEERING; LIFE SCIENCES INSTITUTEElectrical excitation of neural tissue has wide applications, but how electrical stimulation interacts with neural tissue remains to be elucidated. Here, we propose a new theory, named the Circuit-Probability theory, to reveal how this physical interaction happen. The relation between the electrical stimulation input and the neural response can be theoretically calculated. We show that many empirical models, including strength-duration relationship and linear-non-linear-Poisson model, can be theoretically explained, derived, and amended using our theory. Furthermore, this theory can explain the complex non-linear and resonant phenomena and fit in vivo experiment data. In this letter, we validated an entirely new framework to study electrical stimulation on neural tissue, which is to simulate voltage waveforms using a parallel RLC circuit first, and then calculate the excitation probability stochastically.Publication Mapping of Small Nerve Trunks and Branches Using Adaptive Flexible Electrodes(2016) Xiang, Z; Sheshadri, S; Lee, S.-H; Wang, J; Xue, N; Thakor, N.V; Yen, S.-C; Lee, C; ELECTRICAL AND COMPUTER ENGINEERING; LIFE SCIENCES INSTITUTE[No abstract available]Publication Nanotunnels within Poly(3,4-ethylenedioxythiophene)-Carbon Nanotube Composite for Highly Sensitive Neural Interfacing(AMER CHEMICAL SOC, 2020/07/28) Chen, Nuan; Luo, Baiwen; Patil, Anoop C; Wang, Jiahui; Gammad, Gil Gerald Lasam; Yi, Zhigao; Liu, Xiaogang; Yen, Shih-Cheng; Ramakrishna, Seeram; Thakor, Nitish V; Dr Baiwen Luo; ELECTRICAL AND COMPUTER ENGINEERING; LIFE SCIENCES INSTITUTE; MECHANICAL ENGINEERING; CHEMISTRYNeural electrodes are developed for direct communication with neural tissues for theranostics. Although various strategies have been employed to improve performance, creating an intimate electrode-tissue interface with high electrical fidelity remains a great challenge. Here, we report the rational design of a tunnel-like electrode coating comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and carbon nanotubes (CNTs) for highly sensitive neural recording. The coated electrode shows a 50-fold reduction in electrochemical impedance at the biologically relevant frequency of 1 kHz, compared to the bare gold electrode. The incorporation of CNT significantly reinforces the nanotunnel structure and improves coating adhesion by â1.5 fold. In vitro primary neuron culture confirms an intimate contact between neurons and the PEDOT-CNT nanotunnel. During acute in vivo nerve recording, the coated electrode enables the capture of high-fidelity neural signals with low susceptibility to electrical noise and reveals the potential for precisely decoding sensory information through mechanical and thermal stimulation. These findings indicate that the PEDOT-CNT nanotunnel composite serves as an active interfacing material for neural electrodes, contributing to neural prosthesis and brain-machine interface.Publication A Physical Perspective to the Inductive Function of Myelin—A Missing Piece of Neuroscience(Frontiers Media S.A., 2021-01-18) Wang, Hao; Wang, Jiahui; Cai, Guangyi; Liu, Yonghong; Qu, Yansong; Wu, Tianzhun; ELECTRICAL AND COMPUTER ENGINEERINGStarting from the inductance in neurons, two physical origins are discussed, which are the coil inductance of myelin and the piezoelectric effect of the cell membrane. The direct evidence of the coil inductance of myelin is the opposite spiraling phenomenon between adjacent myelin sheaths confirmed by previous studies. As for the piezoelectric effect of the cell membrane, which has been well-known in physics, the direct evidence is the mechanical wave accompany with action potential. Therefore, a more complete physical nature of neural signals is provided. In conventional neuroscience, the neural signal is a pure electrical signal. In our new theory, the neural signal is an energy pulse containing electrical, magnetic, and mechanical components. Such a physical understanding of the neural signal and neural systems significantly improve the knowledge of the neurons. On the one hand, we achieve a corrected neural circuit of an inductor-capacitor-capacitor (LCC) form, whose frequency response and electrical characteristics have been validated by previous studies and the modeling fitting of artifacts in our experiments. On the other hand, a number of phenomena observed in neural experiments are explained. In particular, they are the mechanism of magnetic nerve stimulations and ultrasound nerve stimulations, the MRI image contrast issue and Anode Break Excitation. At last, the biological function of myelin is summarized. It is to provide inductance in the process of neural signal, which can enhance the signal speed in peripheral nervous systems and provide frequency modulation function in central nervous systems. © Copyright © 2021 Wang, Wang, Cai, Liu, Qu and Wu.Publication Novel CMOS-Compatible Mo-AlN-Mo Platform for Metamaterial-Based Mid-IR Absorber(American Chemical Society (ACS), 2017/02/15) Hasan, D; Pitchappa, P; Wang, J; Wang, T; Yang, B; Ho, CP; Lee, C; Assoc Prof Chengkuo Lee; ELECTRICAL AND COMPUTER ENGINEERINGWe demonstrate a new CMOS compatible metal-dielectric-metal (Mo-AlN-Mo) platform of metamaterial absorber for refractory and narrowband applications at mid-IR. Comparison with the recently reported CMOS compatible plasmonic TiN shows superior reflectivity of Mo thin film at mid-IR wavelengths (3-8 μm), while AlN provides large thermal stability and thermal conductivity, mid- to far-IR transparency and both second and third order nonlinear effect and satisfies the matching condition of thermal expansion coefficient with Mo toward minimizing the thermal stress. We demonstrate the proof-of-concept of reducing the thermal stress up to 400° by considering a high stress, CMOS platform of SiO . We further report temporal measurement of the resonance intensity and wavelength-shift of the absorber structures and confirm the robust performance of the platform over prolonged heating. Finally, we propose a method to perform surface enhanced infrared absorption (SEIRA) spectroscopy of biological samples demanding biocompatibility on the massively scalable CMOS platform and demonstrate strong coupling to the amide vibrational bonds of silk fibroin at mid-IR. We envisage the proposed platform will be a versatile avenue for thermophotovoltaic energy conversion and emission at low thermal stress, fast thermal detection, and large scale, low form factor, and integrated sensors with the ubiquitous CMOS technology. 2