Study On Properties Of Flexible Pressure Sensor Based On Carbon Black/Silicone Rubber

Flexible pressure sensor which was based on carbon black and silicone rubber waspreparated with electrodes of different structures in this paper. and its AC characteristicsare deeply investigated and analyzed.The pressure sensor was fabricated with nano-carbon black/silicon rubberconductive composites on the ceramic substrate with interdigital electrodes. It was provedthat Percolation threshold of carbon black/silicone rubber composite is2.5wt%when thedoping concentration of carbon black particles was changed. Piezoresistive charactristicsof sensor were investigated under alternating current. The results demonstrated the sensorexhibited positive piezoresistive effect under a frequency of1kHz. The polarizationintensity of space charges between the interface of nano-carbon black and silicone rubberdecreased and the positive piezoresistive effect weakened as the working frequencyincreased. And its best frequency is1kHz. The effect is explained through the movementbetween carbon black particles. Finally, characteristics of response and recovery areinvestigated.“sandwich” pressure sensor was fabricated with Al electrodes. and its relationshipof resistance、capacity and impedance with the applied pressure was investigated.Movement of carbon black particles and negative pressure-capacitance effect wereanalyzed. Stress tests showed that: the element has fast response and recoverycharacteristic and repeatability. its response and recovery time is4s and5s. The sensorexhibited good gradient and could distinguish interval of0.5N under continuouspressure.Comparisons were made of AC characteristics of two kinds’ sensor. The resultsshowed that the piezoresistive characteristics of sensor under alternating current includedresistance and capacitance. its AC output signal varied, When the device was preparedwith different structures of electrodes."Interdigital"-type of sensor is oriented inresistance, not capacity;"sandwich"-type of sensor is oriented in capacity, not resistance; both kinds of sensors can be used in different types of test system with different signalacquisition.Finally, the flexible pressure based on the substrate of ITO/PET was madethrough lithography. And its piezoresistive characteristics were deeply invrstigated. Itshows that the element has good positive piezoresistive effect with the increasing pressure.Its resistance changes from40k to1200k with the range of0to20N. Meanwhile,the sensor has fast response、recovery and repeatability characteristics under loadedpressure.