Piezoresistive Carbon-based Hybrid Sensor for Body-Mounted Biomedical Applications

4th International Conference on Competitive Materials and Technology Processes

Melnykowycz, M.^1 ; Tschudin, M.^2 ; Clemens, F.^1

Laboratory for High Performance Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland^1

STBL Medical Research AG, Wilen, Switzerland^2

关键词: Biomedical applications;    Carbon black particles;    Human Computer Interaction (HCI);    Mechanical compliance;    Metamaterial structures;    Natural user interface (NUI);    Negative poisson's ratios;    Soft condensed matters;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/175/1/012006/pdf
DOI  :  10.1088/1757-899X/175/1/012006

来源: IOP

【 摘 要 】

For body-mounted sensor applications, the evolution of soft condensed matter sensor (SCMS) materials offer conformability andit enables mechanical compliance between the body surface and the sensing mechanism. A piezoresistive hybrid sensor and compliant meta-material sub-structure provided a way to engineer sensor physical designs through modification of the mechanical properties of the compliant design. A piezoresistive fiber sensor was produced by combining a thermoplastic elastomer (TPE) matrix with Carbon Black (CB) particles in 1:1 mass ratio. Feedstock was extruded in monofilament fiber form (diameter of 300 microns), resulting in a highly stretchable sensor (strain sensor range up to 100%) with linear resistance signal response. The soft condensed matter sensor was integrated into a hybrid design including a 3D printed metamaterial structure combined with a soft silicone. An auxetic unit cell was chosen (with negative Poisson's Ratio) in the design in order to combine with the soft silicon, which exhibits a high Poisson's Ratio. The hybrid sensor design was subjected to mechanical tensile testing up to 50% strain (with gauge factor calculation for sensor performance), and then utilized for strain-based sensing applications on the body including gesture recognition and vital function monitoring including blood pulse-wave and breath monitoring. A 10 gesture Natural User Interface (NUI) test protocol was utilized to show the effectiveness of a single wrist-mounted sensor to identify discrete gestures including finger and hand motions. These hand motions were chosen specifically for Human Computer Interaction (HCI) applications. The blood pulse-wave signal was monitored with the hand at rest, in a wrist-mounted. In addition different breathing patterns were investigated, including normal breathing and coughing, using a belt and chest-mounted configuration.