Flexible capacitive pressure sensors with patterned microstructures have attracted ever-increasing attention in the field of wearable electronics. However, there is still a lack of a reliable method for predicting the performance of flexible piezo-capacitive sensors, leading to difficulty for designing and evaluating microstructures. In this paper, we establish an analytical method for designing flexible capacitive sensors with point-like electrical field concentration and further derive an accurate expression for pyramid electrodes by combining high throughput finite element simulations with machine learning. Besides, we have designed and fabricated a high-performance pressure sensor with the simulation and analysis based on our model. A thin high-k dielectric layer with rough surface is selected as the dielectric layer, yielding a high sensitivity of 0.031 kPa⁻¹ to 0.115 kPa⁻¹ in an ultra-wide pressure range from 3.4 Pa to 2.5 MPa.

There is an urgent demand for polymer dielectrics in the rapidly growing fields of electric vehicles and energy exploration. However, the existing polymer dielectrics suffer from poor energy density due to the decrease of breakdown strength at elevated temperatures, which limits their widespread application. Ultralow content inorganic fillers (< 1 vol.%) with appropriate size have been reported to enhance the polarization of polymer matrix, while their influence on breakdown still lack attention. In this work, we developed the dilute polyetherimide (PEI)-Al₂O₃ nanocomposites with different filler size (5, 20, and 80 nm) and studied the size effect of nanofillers on the breakdown resistance and energy storage performances of nanocomposite dielectrics. Based on the results of multiscale simulations and tests, the dilute fillers with smaller size (5 nm) exhibit more remarkable enhancement on charge trapping and mechanical strengthening of polymer matrix, and thus yielding higher breakdown strength and a discharged energy density of 4.69 J·cm⁻³ (150 °C) and 2.56 J·cm⁻³ (200 °C) with a high efficiency of 90%. A long charge–discharge cycling stability up to 10⁵ cycles was also achieved at 150 °C.

Through the modulation of the dipolar entropy under an applied electric field (E), a reversible temperature change (ΔT) could be achieved in a dielectric material, which is known as the electrocaloric (EC) effect. Among all EC materials, ferroelectric terpolymer P(VDF-TrFE-CFE) has been regarded as one of the most promising EC materials owing to its large EC effect and superior thermal stability. Yet, the low EC strength limits the application of terpolymers in realistic cooling devices. In this work, using the thermal treatment of quenching and low-temperature annealing, the terpolymers with significantly decreased crystalline size are prepared with their EC performances investigated. Compared to the normal ones, the terpolymers with smaller crystalline size exhibit substantially enhanced EC strength. The better EC performance may be mainly attributed to the lower energy barriers for dipole orientation, which gives rise to higher polarization at low electric fields. This work emphasizes the critical role of crystalline size on the macroscopic properties of EC polymers.