Micro-frustum-array Structure With Force-electricity Coupling Enhancement For Flexible Pressure Sensing Technology

Flexible pressure sensor is the main way for measuring pressure parameters and can be integrated with the Internet of Things and cloud computing,thus promoting the development of smart medical and human-computer interaction.However,the development and application of flexible pressure sensor has met several technical bottlenecks.First,the lack of weak pressure perception ability and high sensitivity sensing ability.On the one hand,the sensor with weak pressure perception capacity can sense multiple weak pressure changes,endowing the important physiological signal changes can be detected early and the attack of disease can be reduced and prevented.On the other hand,the high sensitivity sensing capacity can increase the sensor's output performance and measurement range,and then enhance the test reliability and expand application scenarios.Second,the traditional rigid battery,with the drawbacks of inflexibility,large size and big weight,would cause discomfort to the wearer as the power supply for the flexible pressure sensor.Furthermore,the traditional rigid battery cannot provide continuous and stable power supply for the flexible pressure sensor,which makes the device unable to monitor the relevant pressure parameters of human body in real time.To address the above problems,the approach to enhance the force-electric coupling efficiency of the triboelectric/piezoelectric/piezoelectric-enhanced triboelectric flexible pressure sensor is explored,the improvement of the weak pressure perception,sensitivity and measuring range of the sensor by this method is verified,the influence of rigid battery on the wearing comfort and working time of the sensor is eliminated,and the performance and potential application scenarios of the prepared sensor are studied.The main researches are as follows.(1)The research on the force-electricity coupling enhancement based on Maxwell's displacement current transfer theory.The force-electricity coupling mechanism of triboelectric and piezoelectric pressure sensing technology is systematically analyzed.The high efficiency force-electricity coupling method between normal stress and shear stress under multiple degree of freedom condition,and the force-electrical coupling method under piezoelectric-enhanced triboelectric synchronously induced charge output model are proposed.Finally,the PDMS film with micro-frustum-array structure,nanofibers and composite film with high filling ratio are fabricated by exploring the manufacturing process of flexible pressure sensor.(2)The research on the weak pressure perception capacity of the flexible pressure sensor.The micro-frustum-array structure PDMS film-based triboelectric flexible pressure sensor is fabricated based on the high efficiency force-electricity coupling method between normal stress and shear stress under multiple degree of freedom condition.The developed sensor with conformal characteristics has good sensitivity(5.67 V/105 Pa)and could sense weak pressure changes,such as the detailed information of pulse beating and muscle movement.(3)The research on the high sensitivity sensing capacity of the flexible pressure sensor.The piezoelectric-enhanced triboelectric flexible pressure sensor with all-in-one deformationcontact zero-delay structure is fabricated based on the enhancement method under piezoelectric-enhanced triboelectric synchronously induced charge output model.The developed sensor with conformal characteristics has the capacities of weak pressure perception and high sensitivity sensing.Moreover,the developed sensor has high sensitivity(18.96 V/105 Pa)and could sense weak physiological signal and large strain movement signal,such as the detailed information of pulse beating,the pressure of finger sliding and pressing,and the pressure of vola.(4)The research on the flexible and stretchable pressure sensor.The multi-materials mixing process based on the laminar displacement theory is proposed.The piezoelectric flexible and stretchable pressure sensor based on Ba Ti O3/Ecoflex composite film is fabriccated to achieve the perfect fit with human skin.Especially,the stretch rate of Ba Ti O3/Ecoflex composite film can reach 467%.The developed sensor has good electric output and excellent stretchability,which could be attached on the outside of elbow joint to monitor the joint movement under different bending angles and bending speeds.The proposed force-electrical coupling enhancement solves the problem of low weak pressure perception capacity for the triboelectric flexible pressure sensor with skin-conformal characteristic,the problems of low measurement range and low sensitivity sensing capacity for the piezoelectric-enhanced triboelectric flexible pressure with skin-conformal characteristic,and the problem of large strain motion monitoring for the flexible pressure sensor.This research provides a new way for the design system of flexible pressure sensor,showing the broad application in the field of smart medical and human-computer interaction.