Human skin interactive self-powered wearable piezoelectric bio-e-skin by electrospun poly-l-lactic acid nanofibers for non-invasive physiological signal monitoring.

Flexible and wearable piezoelectric bio e-skin (PBio-e-skin) based on electrospun poly(l-lactic acid) PLLA nanofiber membrane is demonstrated for non-invasive human physiological signal monitoring and detecting dynamic tactile stimuli. The molecular orientations of the C[double bond, length as m-dash]O dipoles by electrospinning technique result in a longitudinal piezoelectric charge co-efficient (d33) value of ∼(3 ± 1) pm V-1 realized by piezoresponse force microscopy, allowing the PBio-e-skin for pressure sensing applications. The robust mechanical strength (Young's modulus ∼50 MPa) of nanofiber membrane ensures PBio-e-skin's superior operational stability over 375 000 cycles. Owing to the superior mechanosensitivity of ∼22 V N-1, PBio-e-skin has the ability to measure subtle movement of muscle in the internal organs such as esophagus, trachea, motion of joints and arterial pressure by recognition of strains on human skin. This flexible and light weight PBio-e-skin precisely detects vital signs and provides important clinical insights without using any external power source. Eventually, the low cost, environmental friendly PBio-e-skin will have a huge impact in a broad range of applications including self-powered wearable health care systems, human-machine interfacing devices, artificial intelligence and prosthetic skin.