The human skin can accurately perceive the intensity and location of tactile signals. However, flexible electronic skins that mimic the structure and function of human skin typically rely on high-density sensor arrays for perceiving pressure locations, including backend data processing and display device integration.
Currently, strategies for visualizing pressure on electronic skin often involve pressure-driven luminescence and color-changing. While this method achieves high spatial resolution, pixelated array designs have high processing requirements, and crosstalk between pixels significantly reduces optical contrast.
To address this, researchers from Shenzhen Technology University have proposed a novel ionic skin that combines pressure sensing with in-situ non-pixel pressure display. Their findings were published in "Nano Letters." By patterning the ionic interface in electrochromic devices, the researchers achieved pressure-driven interface charge transfer, causing changes in system capacitance and controlling localized color-changing behavior in response to pressure distribution, thereby characterizing the magnitude and distribution of pressure loads.
This system not only displays static pressure distribution but also tracks dynamic pressure trajectories. It offers a spatial resolution of less than 1 millimeter and a color contrast of 160 nanometers. By adjusting the device's voltage direction, the displayed pressure distribution map can be erased and reset multiple times. In terms of electrical sensing, this system can generate uniform capacitance signals within a range of 20 kilopascals, with a pressure resolution of 2 pascals and a response time of 0.06 seconds. This dual-mode electrical/optical response to pressure enables synchronous monitoring of skin deformation size and position in skin signal monitoring, providing richer physiological information compared to traditional flexible pressure sensors.
This research introduces a new strategy for pressure sensing and display, eliminating the dependence on sensor arrays and pixelated display devices for traditional pressure displays. It achieves high sensitivity, resolution, and contrast in dual-mode electrical/optical pressure sensing, offering new possibilities for the design of smart devices based on electronic skin and human-machine interaction.
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Illustration of in-situ display of pressure distribution and detection of pressure magnitude on ion skin. Image provided by the research team.
