Hu Jiyong

Electrical Properties of PPy-Coated Conductive Fabrics for Human Joint Motion Monitoring

Abstract Body motion signals indicate several pathological features of the human body, and a wearable human motion monitoring system can respond to human joint motion signal in real time, thereby enabling the prevention and treatment of some diseases. Because conductive fabrics can be well integrated with the garment, they are ideal as a sensing element of wearable human motion monitoring systems. This study prepared polypyrrole conductive fabric by in situ polymerization, and the anisotropic property of the conductive fabric resistance, resistance–strain relationship, and the relationship between resistance and the human knee and elbow movements are discussed preliminarily.

Improving the electromagnetic shielding of nickel/polyaniline coated polytrimethylene-terephthalate knitted fabric by optimizing the electroless plating conditions:

To solve electromagnetic interference of electronic devices and health issues by the expansion of the electronic industry and the extensive use of electronic equipment, flexible and stretchable conductive elastic textiles are beneficial. This study prepared conductive Ni/polyaniline (PANi)/polytrimethylene-terephthalate (PTT) composite fabric by in situ chemical polymerization and electroless nickel plating. Their direct current electrical resistance and the shielding efficiency energy were tested. Furthermore, the effect of electroless plating conditions was investigated on surface resistivity and electromagnetic shielding effectiveness (EMSE) of the composite fabric, and the correlation between electrical resistivity and EMSE was explored. The results show that the shielding efficiency energy of Ni/PANi/PTT composite fabric optimized can reach more than 40 dB and at a given frequency it has an inverse parabolic relation with the electroless plating conditions. In addition, when the electroless plating conditions is the determinant, the SE has little change in the electromagnetic wave frequency, especially in the frequency range of 600 MHz or more. It is concluded that the EMSE of the Ni/PANi/PTT conductive fabrics could be tailored by modifying the chemical reagent contents in the electroless plating solution.

Effect of electrospinning parameters on piezoelectric properties of electrospun PVDF nanofibrous mats under cyclic compression

Abstract The high piezoelectric response capacity of electrospun PVDF nanofibers is currently a challenging area of research, and this study attempts to optimize the piezoelectric properties of electrospun PVDF nanofibrous mat under controlled electrospinning process. Some experiments were designed to study the relationship between electrospinning processing parameters and the piezoelectric properties of PVDF mats under cyclic compression, and this relationship was compared with the change of crystalline structure features with the electrospinning parameters. The excitation method is based on low velocity compression test by cyclically pressing flat contactor on samples. The impact of each of processing parameters has been investigated. It was found that three electrospinning parameters including: applied voltage, feeding volume flow rate and syringe needle tip diameter, are significant influential factors to the piezoelectric properties of the electrospun PVDF nanofibrous mats. However, the feeding volume flow rate has a greater effect on the piezoelectric responses to cyclic compression than both applied voltage and volume flow rate does, and its effect on the piezoelectric responses is different from that of β-phase fraction of crystalline structure within PVDF nanofiber. It was also observed that the relationship between the piezoelectric peak intensity and the applied voltage as well as the feeding volume flow rate is nonlinear.

Dependence of sheet resistance of nickel-plated PANi/PTT composite fabric on electroless plating conditions

Flexible and stretchable conductive composite fabrics have wide applications, including wearable sensors, antenna, electrodes, solar batteries, signal, or power transmission. For most of applications, the electrical conductive fabrics need a low sheet resistance and antioxidation. To improve the stability and the electrical conductivity of PANi/PTT composite conductive fabric, some conductive composite fabrics were prepared by electroless nickel plating on PANi/PTT composite fabrics in the aqueous nickel sulfate solutions. The sheet electrical properties of the composite fabric were evaluated by the van der Pauw method, and the effect of the chemical plating conditions such as reducing agent, complexing agent, and buffer agent concentrations were investigated on the sheet resistance as well as the mechanical properties of fabric substance. The results show that the lower sheet resistance of composite fabrics was observed at the concentrations of NiSO4, 25 g/L, NaH2PO2, 20 g/L, Na3C6H5O7, 15 g/L, CH3COONa, 20 g/L, respectively. Additionally, the mechanical properties of the Ni/PANi/PTT composite fabrics were improved in comparison with those of PANi/PTT composite fabrics.