Flexible Ferroelectric Sensors with Ultrahigh Pressure Sensitivity and Linear Response over Exceptionally Broad Pressure Range

Abstract

Flexible pressure sensors with a high sensitivity over a broad linear range can simplify wearable sensing systems without additional signal processing for the linear output, enabling device miniaturization and low power consumption. Here, we demonstrate a flexible ferroelectric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry. Due to the stress concentration between interlocked microdome arrays and increased contact area in the multilayer design, the flexible ferroelectric sensors could perceive static/dynamic pressure with high sensitivity (47.7 kPa, 1.3 Pa minimum detection). In addition, efficient stress distribution between stacked multilayers enables linear sensing over exceptionally broad pressure range (0.0013-353 kPa) with fast response time (20 ms) and high reliability over 5000 repetitive cycles even at an extremely high pressure of 272 kPa. Our sensor can be used to monitor diverse stimuli from a low to a high pressure range including weak gas flow, acoustic sound, wrist pulse pressure, respiration, and foot pressure with a single device.

Flexible Multifunctional Sensors for Wearable and Robotic Applications

“…[50][51][52] Piezoelectric materials can be directly used as self-powered sensors [49] to sense strain, force, and acceleration, and the pyroelectric properties of such materials, see Figure 2, also enables them to be used as thermal sensors. Therefore, advanced materials, such as flexible piezoelectric composites, [54,55] thin piezoelectric films, [56] and nanofibers, [57,58] have been intensively investigated for their improved piezoelectric performance, cost-effectiveness, and mechanical flexibility. Although these piezoelectric ceramics have high piezoelectric performance due to their high levels of polarization, they are too brittle to be readily integrated into flexible electronics.…”

“…In order to mimic the interlocked ridge structures between dermal-epidermal layers of human fingertip, Park et al [73] proposed a single-layer interlocking e-skins with PVDF and reduced graphene oxide (rGO) microdome structure; see the left two images in Figure 5c. [73] Based on Park's work, Lee et al [55] fabricated an e-skin with three stacked interlocked microdome layers, which is demonstrated in Figure 5d. Fingertip-like microridge patterns on the surface and interlocked microdome arrays were used to amplify tactile signal by pressure, temperature, and vibration.…”

“…[75] Magneto-electric coupling composites possess both a magnetostrictive phase and piezoelectric phase, and their electric polarization can be controlled by the external magnetic field or electric field. [55] Copyright 2018, American Chemical Society. Multifunctional sensors combined piezoelectric and piezoresistive effect.…”

Large‐Area Fabrication of High‐Performance Flexible and Wearable Pressure Sensors

“…Recently, smart insoles for foot pressure detection have been reported, [3,16,36,37] which provide feasible solutions for footwear design, sports performance analysis, and injury prevention. Hence, foot health is of great significance to our well-being.…”

Interfaceless Strain and Pressure‐Sensitive Stretchable Capacitor Based on Self‐Bonding and Surface Morphology Control of a Reversibly Crosslinkable Silicone Elastomer

“…Stretchable strain and pressure sensors, which can provide significant information about the specific demands inside the human body and in the processes where humans contact with their external environment, [1][2][3][4][5] have gained significant interest recently because of their versatile applications in robotic systems, [6] electronic skin, [7] prosthetics, [8] and wearable medical devices. [9,10] To date, various sensing mechanisms have been reported to achieve strain and pressure sensitivity using piezoelectric, [11][12][13] piezoresistive, [14,15] triboelectric, [16,17] and piezocapacitive materials.…”