Sensitive, Stretchable, and Sustainable Conductive Cellulose Nanocrystal Composite for Human Motion Detection

Sensitive strain sensors (an important component of soft robotics, wearable devices, and biomedical electronics) with high sensitivity, stretchability, and long-term stability are still challenging. A sensitive, stretchable, and sustainable sensor using poly­(3,4-ethylenedioxythiophene) (PEDOT) coated cellulose nanocrystals (CNC) with poly­(vinyl alcohol)/glycerol (PVA/Gly) composite is proposed. The low cost and sustainable PEDOT coated CNC with high aspect ratio lowered the electrical percolation threshold that significantly improved the electrical conductivity leading to better sensitivity (gauge factor = 21.25) compared to the PEDOT applied film without CNC (gauge factor = 9.35). The exceptional stretchability of up to 500% and a low Young’s modulus with long-term stability exceeding 3 months are due to the glycerol plasticizer. The fabricated sensors possessed outstanding real-time strain sensing capability for a series of human motions, including complex joint bending motions, subtle muscle motions, wrist pulse, and excellent self-healing ability. This effective green strategy for preparing a highly stretchable conductive composite addresses current limitations in strain sensor preparation and offers a sustainable approach to sensor design and development.