High Sensitivity and Wide Linear Range Flexible Piezoresistive Pressure Sensor with Microspheres as Spacers for Pronunciation Recognition

Abstract

Flexible piezoresistive pressure sensors have received great popularity in flexible electronics due to their simple structure and promising applications in health monitoring and artificial intelligence. However, the contradiction between sensitivity and detection range limits the application of the sensors in the medium-pressure regime. Here, a flexible piezoresistive pressure sensor is fabricated by combining a hierarchical spinous microstructure sensitive layer and a periodic microsphere array spacer. The sensor achieves high sensitivity (39.1 kPa −1 ) and outstanding linearity (0.99, R 2 coefficient) in a medium-pressure regime, as well as a wide range of detection (100 Pa−160.0 kPa), high detection precision (<0.63‰ full scale), and excellent durability (>5000 cycles). The mechanism of the microsphere array spacer in improving sensitivity and detection range was revealed through finite element analysis. Furthermore, the sensors have been utilized to detect muscle and joint movements, spatial pressure distributions, and throat movements during pronouncing words. By means of a full-connect artificial neural network for machine learning, the sensor's output of different pronounced words can be precisely distinguished and classified with an overall accuracy of 96.0%. Overall, the high-performance flexible pressure sensor based on a microsphere array spacer has great potential in health monitoring, human−machine interface, and artificial intelligence of medium-pressure regime.

Nanoengineering Ultrathin Flexible Pressure Sensors with Superior Sensitivity and Wide Range via Nanocomposite Structures

“…In the microengineering strategy, researchers have demonstrated the possibility to adjust the performance of the sensor by changing the size and density of the microstructures. ,, Similarly, to further enhance the performance of this sensor, we can adjust the morphology of the nanostructure by varying the size and density of the PS spheres. This will enable us to fine-tune the sensor’s characteristics, such as sensitivity, detection range, and linearity.…”

“…Recently, to improve the detection range of sensors, Huang et al introduced a method using poly(methyl methacrylate) (PMMA) microspheres as isolation spacers for thick sensors. This approach successfully developed a flexible piezoresistive pressure sensor with a detection range of up to 160 kPa and a sensitivity of 39.1 kPa –1 . Fundamentally, the sensing mechanism of flexible pressure sensors employing microengineering strategies is the same as early flexible pressure sensors, both based on the compression of the active layer.…”

Fabrication of Flexible Capacitive Pressure Sensors by Adjusting the Height of the Interdigital Electrode

“…In recent years, flexible pressure sensors, as an important branch of wearable electronic devices, have developed rapidly and have been widely applied in fields such as intelligent perception, human–computer interaction, gesture recognition, medical health, and electronic skin. − Flexible pressure sensors involve a wide variety of types, which can be classified according to their working principles into piezoresistive, − piezoelectric, , capacitive, − triboelectric, − and so on. Among them, capacitive pressure sensors stand out for their high stability, low power consumption, fast response time, and simple architecture.…”