“Soft Electronics and Sensors for Wearable Healthcare Applications”

Thesis lab: Chuan Wang (WashU Electrical & Systems Engineering)

Abstract: Wearable electronics are becoming increasingly essential to personalized medicine by collecting and analyzing massive amounts of biological signals from internal organs, muscles, and blood vessels. Conventional rigid electronics may lead to motion artifacts and errors in collected data due to the mismatches in mechanical properties between human skin. Instead, soft wearable electronics provide a better platform and interface that can form intimate contact and conformably adapt to human skin. In this respect, this thesis focuses on new materials formulation, fabrication, characterization of  low-cost, high sensitivity and reliable sensors for wearable health monitoring applications.

More specifically, we have studied the silver nanoparticles (AgNPs) inkjet-printed on a polydimethylsiloxane (PDMS) substrate that offers great pressure sensitivity for arterial pulse monitoring. In addition, we have investigated the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(ethylene oxide) PEO polymer blends that exhibit low sheet resistance and can resist up to 50% of tensile strain. The highly stretchable thin film can serve as interconnects between electronic components and dry electrodes for photoplethysmography (PPG) and electrocardiography (ECG) recordings. Based on the developed PEDOT:PSS solution with high conductivity, we fabricated a porous PDMS sponge coated with conductive PEDOT:PSS to make electrodes with reduced electrode-skin contact impedance, improved signal-to-noise ratio and is suited for long-term and motion-artifact-tolerant recording of high quality biopotential signals including ECG and electromyography (EMG). Finally, we demonstrated a multimodal sensor based on the porous PEDOT:PSS/PDMS sponge for sensing and distinguishing of pressure, strain and temperature from different trends in resistance and capacitance response. Applications including object detection, gesture recognition and temperature sensing have all been demonstrated. In this thesis, the proposed materials, sensor design, low-cost inkjet printing and dip-coating fabrication process open the possibility for more complex epidermal wearable health monitoring electronic systems.

Dissertation Examination Committee

• Prof. Chuan Wang, Chair
• Prof. Shantanu Chakrabartty
• Prof. Julio D’Arcy
• Prof. Srikanth Singamaneni
• Prof. Yong Wang

For inquiries contact Beth Gartin.