Coconut-coir modified with nanoparticles for flexible sensors and energy harvesting applications

Eco-friendly nanoparticles modified-coconut coir based capacitive sensors (C, CN, CI, CIN and I ) were fabricated. Compressive pressure led to a reduction in their thickness and lowered the frequencies to 49.8∼50.7Hz. In terms of resistance-pressure change, the sensor I generally recorded the best sensitivity (S), with the highest value (0.68kPa -1 , r 2 ∼0.9) obtained within 0.26∼0.44kPa ranges. Also, sensor I exhibited an ultra-sensitive voltage detection at all pressure ranges, with the highest value (48.5kPa -1 ) recorded at 0∼0.17kPa with a strong linearity (r 2 ∼0.998). In detection of capacitance, CN was very effective at lower pressure range; 0∼0.087kPa while sensor I outperformed CN as elevated pressure 0.087∼5.2kPa. Sensor I was also effective in energy harvesting analysis, especially at elevated pressures. In terms of flexibility study, the order of the absolute gage factor (GF) of the sensors was I (GF∼0.25, r 2 ∼0.995) > CN (GF∼0.084, r 2 ∼0.97) > C (GF∼0.082, r 2 ∼0.91) > CI (GF∼0.061, r 2 ∼0.94) > CIN (GF∼0.082, r 2 ∼0.91). The sensors exhibited consistency and stability even after 2000 cycles of detections, linked to the porous nature of the coir and the suitable elastic fatigue acrylic used. Thus, coconut coir waste has been demonstrated to meet green electronics and circular economy goals by enhancing the biodegradability of capacitive sensors.