A semitransparent snake-like tactile and olfactory bionic sensor with reversibly stretchable properties

Many organisms and animals have sensing abilities that are different from those of human beings; for example, snakes have strong smell-, vibration-, touch- and heat-sensing abilities. A nature-mimicking sensing platform capable of sensing multiple stimuli, such as strain, pressure, temperature and other uncorrelated conditions, is highly desirable to broaden the applications of sensors. Here, we construct a semitransparent intelligent skin-like sensing platform based on polyaniline (PANI) nanowire arrays that can act as a bionic component by simultaneously sensing tactile stimuli and detecting colorless, odorless gas. Our multifunctional bionic sensing strategy is remarkably adaptive for versatile applications. The strain-sensing performance is superior to that of most conducting polymer-based sensors reported so far and is comparable to or even better than traditional metal and carbon nanowire/nanotube-based strain sensors. The highest gauge factor demonstrated is 149, making our system a remarkable candidate for strain-sensing applications. The sensor can accurately detect a wide range of human motions. We also demonstrate the simultaneous controlled olfaction ability for the detection of methane with high sensitivity and a fast response time. These results enable the realization of multifunctional and uncorrelated sensing capabilities, which will afford a wide range of applications to augment robotics, treatment, simulated skin, health monitoring and bionic systems. A wearable sensor can track full-range human motion and sniff out toxic gases using polymer nanowires with features similar to snakeskin. The device, which was developed by Pooi See Lee and co-workers at Nanyang Technological University, is based on polyaniline, a conducting polymer with natural flexibility and chemical sensitivity. Polyaniline often becomes unworkably rigid when deposited as a thin film, but the Singapore-based team avoided this issue by growing a vertical forest of polymer nanowires on a thin silicone support. Scanning electron microscopy revealed that when stretched, the nanowires formed scale-like islands and cracks that alter the resistance of the thin film. The researchers demonstrated that these electrical changes were sensitive enough to use for forehead sensors of breathing and eye movement and as a ‘smelling skin’ for detecting methane–an odorless and explosive gas. A semitransparent intelligent skin-like sensor platform based on polyaniline nanowire arrays was constructed, which can act as bionic component by simultaneously sensing tactile stimuli and detecting colorless odorless gas. The highest gauge factor demonstrated is 149, making it a remarkable candidate in strain sensing applications. Simultaneously, we demonstrate the controlled olfaction ability of the sensor with the detection of methane with high sensitivity and fast response time. These results enable the realization of multifunctional and uncorrelated sensing capabilities that will have wide range applications to augment robotics, treatment, simulate skin, health and bionic system.