Bioinspired design of highly sensitive flexible tactile sensors for wearable healthcare monitoring

The design of microscale architectures integrated with low-dimensional nanomaterials for tactile sensors has attracted considerable attention owing to their high performance for various potential applications, especially in the field of healthcare monitoring. However, there still remains a critical challenge to achieve high sensitivity in response to different magnitude external pressure. Herein, we introduce a high performance capacitive tactile sensor based on Silver nanowires coated biomimetic hierarchical array architecture, which consists of mini-domes by the way of vacuum adsorption from through-hole arrays and micro-cones by duplicating Calathea zebrina leaf, respectively. This hybrid graded microstructure as electrode exhibits remarkably improved sensitivity and stimulus responding range when compared with the other monotonous counterparts. Moreover, an optimized ionic gel film with remarkable interfacial capacitance is sandwiched by microstructured electrodes as the dielectric layer, further boosting the performance of the tactile sensor. As a result, the obtained sensor demonstrates a board detection range from 24 Pa to 90 kPa with a maximum sensitivity of 37.8 kPa−1, and a fast response time (<78 ms). These superior performances of our tactile sensor lay a foundation for various applications in healthcare monitoring. It can not only sense and distinguish subtle arterial pulse signals even under different ages, genders and states of motion but also monitor physiological activity with large pressure as well, such as breathing, plantar pressure, and so on. We envision this bionic tactile sensor holds great potential in wearable electronics.