Multi-sized planar capacitive pressure sensor with ultra-high sensitivity

It is now widely accepted that the capacitive pressure sensor has potential benefits for future robotic technologies, human-machine interface, artificial intelligence and health monitoring devices. Despite this fact, the conventional stacked structure including an intermediate dielectric layer between the neighboring electrode layers usually possesses considerable device thickness and size, thus imposing limits on the applicable scale. Here we develop a planar structured pressure sensor without the integrated elastic dielectric layer, and ultra-high sensitivity is achieved enabled by the emerging charge exchange channels between neighboring electrodes induced by external touching stimuli. Each pixel can be fabricated within a several-micrometer range and a tiny pressure of 0.02 Pa would result in a 750% increase in the relative capacitance (equivalent sensitivity of 3.75 × 10⁵ kPa⁻¹ for 0–0.05 Pa, exceeding all the previous reports to date). The working mechanisms are quantitatively investigated and proved to be applicable to macro-sized devices. Simultaneously, we illustrate the capabilities of such sensors by using them to perform static pressure mapping, generating capacitance signals to reflect its own surface morphology when the AFM tip passes by, detecting fingers touching, recording real-time human breath, and distinguishing the contact position.