arXiv subjects

Haiwu Zheng

Publications and source records attributed to Haiwu Zheng.

3 recordsLinked to original sources

arXiv2023

A Health Monitoring System Based on Flexible Triboelectric Sensors for Intelligence Medical Internet of Things and its Applications in Virtual Reality

The Internet of Medical Things (IoMT) is a platform that combines Internet of Things (IoT) technology with medical applications, enabling the realization of precision medicine, intelligent healthcare, and telemedicine in the era of digitalization and intelligence. However, the IoMT faces various challenges, including sustainable power supply, human adaptability of sensors and the intelligence of sensors. In this study, we designed a robust and intelligent IoMT system through the synergistic integration of flexible wearable triboelectric sensors and deep learning-assisted data analytics. We embedded four triboelectric sensors into a wristband to detect and analyze limb movements in patients suffering from Parkinson's Disease (PD). By further integrating deep learning-assisted data analytics, we actualized an intelligent healthcare monitoring system for the surveillance and interaction of PD patients, which includes location/trajectory tracking, heart monitoring and identity recognition. This innovative approach enabled us to accurately capture and scrutinize the subtle movements and fine motor of PD patients, thus providing insightful feedback and comprehensive assessment of the patients conditions. This monitoring system is cost-effective, easily fabricated, highly sensitive, and intelligent, consequently underscores the immense potential of human body sensing technology in a Health 4.0 society.

eess.SP↗

arXiv2023

Polyimides Crosslinked by Aromatic Molecules and Nanocomposites for High Temperature Capacitive Energy Storage

High temperature polymer-based dielectric capacitors are crucial for application in electronic power systems. However, the storage performance of conventional dielectrics polymer dramatically deteriorates due to the thermal breakdown under concurrent high temperatures and electric fields, and there are hardly reports on the causes of thermal breakdown from the aspects of the high temperature conduction loss and Joule heat dissipation. Herein, a combined strategy of crosslinking and compositing for polyimide-based nanocomposites is proposed, which minimizes the thermal breakdown by significantly inhibiting the high-temperature conduction loss and enhancing the high thermal conductivity. Furthermore, the rationale of the strategy was theoretically and experimentally verified from multiple perspectives. The charge-trapping effect is directly observed and quantitatively probed by Kelvin probe force microscopy with nano level resolution, indicating that the crosslinking network introduces local deep traps and effectively suppresses the charge transport. The thermal conductivity of the nanocomposites inhibits the high temperature thermal breakdown, which is confirmed by phase field simulations. Consequently, the optimized nanocomposites possess an ultra high discharge energy density(Ud) of 5.45 J/cm3 and 3.54 J/cm3 with a charge discharge efficiency, respectively, which outperforms the reported polyimide based dielectric nanocomposites. This work provides a scalable direction for high temperature polymer based capacitors with excellent performance.

physics.app-ph↗

arXiv2023

Investigation of the topography-dependent current in conductive AFM and the calibration method

The topography and the electrical properties are two crucial characteristics in determining roles and functionalities of materials. Conductive atomic force microscopy (CAFM) is widely recognized for its ability to independently measure the topology and conductivity. The increasing trend towards miniaturization in electrical devices and sensors has encouraged an urgent demand for enhancing the accuracy of CAFM characterization. However, the possibility of topography interference with the measured current during CAFM scanning leads to an inaccurate estimation of the sample's conductivity. Herein, we investigated the topography-dependent current originating from variation in capacitance between the probe and sample during CAFM testing. Based on the linear dependence between the current and the first derivative of height derived from topographic mapping, the calibration method has been proposed to eliminate the current error that is attributed to the variation in height on sample surfaces. This method is evaluated on one-dimensional ZnO nanowire, two-dimensional (2D) NbOI2 flake, and biological lotus leaf, further demonstrating the feasibility and university of this method. This work effectively addresses the challenge of topographic crosstalk in CAFM characterization, which provides significant benefits for research on demanding high-accuracy CAFM measurements.

physics.app-ph↗