Highly sensitive electronic skin with a linear response based on the strategy of controlling the contact area

Highlights: • Large area micro-nano structure were obtained by using cheap industrial sandpaper as template. • The linear response of the e-skin in the pressure range of 100 kPa is realized by controlling the contact area. • The dielectric material with high dielectric constant makes the sensitivity of the device as high as 26.6 kPa⁻¹. Due to its unique advantages, capacitive electronic skin (E-skin) has shown excellent application potential in robotics, human-computer interaction, and biomedical equipment in recent years. However, the low sensitivity and nonlinear response caused by the classic working mechanism of compressing the microstructured elastic dielectric layer and the low dielectric constant of the elastomer limit practical applications of E-skin. To make the device respond linearly to pressure over a wide range, a new strategy of controlling the contact area between the elastic electrode and the dielectric layer is adopted. This design also reduces signal distortion, which originates from the viscoelasticity of the polymer. Furthermore, by using ferroelectric polymers and ionic gels with high capacitance in the dielectric layer, the sensitivity of the device can be adjusted in the range of 0.644–26.6 kPa⁻¹, and the lower limit of pressure detection is as low as 2.88 Pa. The performance of the device remains stable even after 8000 cycles of compression. On this basis, the successful application of the linear-response E-skin obtained in this work in physiological signal monitoring and the collection of basic object information, such as shape and hardness, proves the rationality of the design and provides the possibility for capacitive electronic skin to move towards real life applications.