Double layer carbon-nanoparticle-based flexible pressure sensor with high precision and stability

Recently, the development of electronic skin and smart wearable sensor have put forward high requirements for flexible sensor with excellent performance. As for a flexible sensor, precision and stability are also significant parameters besides the sensitivity and measuring range. Flexible piezoresistive sensors based on nanomaterial/nanostructure have been reported to possess the high sensitivity. Precision and stability are also important for a sensor, hence we focused on promoting them in this paper. Furthermore, a mechanism for random error generated by a nano-based piezoresistive sensor was proposed. Based on the mechanism, a certain high frequency testing signal was used instead of the direct current signal to promote the precision of the sensor. The relative random error of the sensor decrease greatly above 800 kHz (by three order at low pressure range), which increase the precision greatly. Long-term stability was tested using a total of 12 000 consecutive compression tests. After a 250 s aging process, the sensor remained incredibly stable and only 0.08% change occurred which is much better than those of reported sensors. The sensor also possessed a sensitivity of 0.24 kPa⁻¹ and a linear measuring range of 0–4 kPa. Some applications, including respiratory/arterial pulse measurement and gait recognition, were demonstrated finally.