Touch position identification based on a flexible array-less supercapacitive tactile sensor

Flexible tactile sensors with simple structures, minimal peripheral electric connections and straightforward data processing will benefit the human-machine interactions in which the contact information is crucial. However, it is still hard to balance the easy fabrication, full flexibility, large measurement area and minimal electric connection in existed tactile sensing systems. This study introduces an innovative positioning method based on a flexible supercapacitive tactile sensor. A 100 mm×100 mm prototype sensor, which contains two layers of flexible electrodes and a layer of ionic gel membrane in the middle to construct electrostatic double-layer capacitors (EDLCs), is developed to study the underlying physical principles. Following the established method, minimized electric connections are needed to achieve the mm-scale touch position/movement trace identification. Under the touch pressure, the formation of supercapacitors around the touch area leads to re-distribution of electric potential within the sensor. The electrical voltage variation is gauged at four points, and the data are calculated to estimate the touch positions following a two-step protocol. The developed method demonstrates high accuracy of position identification (around 5% in the 100 mm×100 mm flexible sensor), superior anti-disturbance capability (more than ∼104 variation of capacitance) and fast response (∼ms level). At the same time, it has no dependency on complex fabrication, redundant electric circuit or sensing unit arrays. These promising characteristics can benefit various application fields, such as intelligent robotics, biomedical devices and wearable equipment.