Printed textile-based dry electrodes for impedance plethysmography measurements

In this work, we report on the design, fabrication, and characterization of dry electrodes for the measurement of pulse plethysmography signals from distal arteries via electrical impedance. Four finger-track electrode designs were fabricated using a screen-printing technique, employing a stretchable Ag paste on a TPU stretchable substrate transferred to a textile structure. Electromechanical measurements (i.e. resistance (Ω) versus elongation (mm)) showed the confirmation of three distinct stages: stretchability, relaxation, and swelling on the printed tracks, where the finger tracks #1, #2, and #4 demonstrated a stable return to zero resistance and track #3 exhibited a negative return-to-zero value, with a decrease of a normalized resistance of 0.5 Ω. Furthermore, a preliminary test with the electrodes, demonstrates plethysmography signal waveforms are comparable to typical waveforms obtained with disposable gel electrodes.