NiO nanofibers interspersed sponge based low cost, multifunctional platform for broadband UV protection, ultrasensitive strain and robust finger-tip skin inspired pressure sensor

We report for the first time a low cost, tactile, high performance, multifunctional sensing platform for applications namely broadband Ultraviolet (UV) filter, strain sensor and finger-tip based pressure sensor. Ecofriendly, light weight and mechanically stable melamine sponge (MS) was chemically engineered using electrospun NiO nanofibers for facile fabrication of the tactile sensor. Detailed characterization studies revealed NiO nanofibers interspersed within the structure of hexagonal voids present in melamine sponge. Under optimal conditions, the UV filter exhibited a remarkable UPF (UV Protection Factor) of 87.7, the strain sensor exhibited a gauge factor of 34 with a maximum strain withstanding capability of 76.3% and the pressure sensor displayed a wide dynamic sensing range of 50 N-700 N with a sensitivity 3.75 kPa(-1) which are significantly higher than similar sensors fabricated using advanced methodologies. Furthermore, the device was found to be highly robust and displayed excellent stability up to 500 cycles of bending. The mechanism of the multifunctional sensor can be attributed to the controllable deformation of NiO nanofibers distributed across the melamine sponge upon external strain and pressure. The sensor was successfully demonstrated as strain sensor and pressure sensor for wearable motion detection and ultra-sensitive virtual keyboard applications respectively. The strategy employed here paves way towards integrating multiple devices to develop versatile, clean room-free, low-cost, multifunctional sensors useful in consumer electronics and healthcare.