Recent interest in the fields of human motion monitoring, electronic skin and human-machine interface technology demand strain sensors with high stretchability/compressibility (ε > 50%), high sensitivity (or gauge factor (GF > 100) and long-lasting electromechanical compliance. However, current metal and semiconductor-based strain sensors have very low (ε < 5%) stretchability or low sensitivity (GF < 2), typically sacrificing the stretchability for high-sensitivity. Composite elastomer sensors are a solution where the challenge is to improve the sensitivity to GF > 100. We propose a simple, low cost fabrication of mechanically compliant, physically robust metallic carbon nanotube (CNT)-polydimethylsiloxane (PDMS) strain sensors. The process allows the alignment of CNTs within the PDMS elastomer, permitting directional sensing. Aligning CNTs horizontally (HA-CNTs) on the substrate before embedding in the PDMS reduces the number of CNT junctions and introduces scale-like features on the CNT film perpendicular to the tensile strain direction, resulting in improved sensitivity compared to vertically-aligned CNT-(VA-CNT)-PDMS strain sensors under tension. The CNT alignment and the scale-like features modulate the electron conduction pathway, affecting the electrical sensitivity. Resulting GF are 594 at 15 % and 65 at 50 % strains for HA-CNT-PDMS and 326 at 25 % and 52 at 50 % strains for VA-CNT-PDMS sensors. Under compression, VA-CNT-PDMS show more sensitivity to small-scale deformation than HA-CNT-PDMS due to the CNT orientation and the continuous morphology of the film, demonstrating that the sensing ability can be improved by aligning the CNTs in certain directions. Furthermore, mechanical robustness and electromechanical durability are tested for over 6000 cycles to up to 50 % tensile and compressive strains, with good frequency response with negligible hysteresis. Finally, both types of sensors are shown to detect small-scale human motions, successfully distinguishing various human motions with reaction and recovery times of as low as 130 ms and 0.5 s respectively.

A NiO nanoparticle-based, inkjet-printable ink and a saturated magnesium perchlorate aqueous gel electrolyte with 1.5 V voltage window were developed and used to fabricate high performance micro-supercapacitors through inkjet printing technology.

A new post-treatment method for lead–tin mixed perovskites enabling device fill factors approaching 83%.