Research On Highly Sensitive And Flexible Fingertip Tactile Sensing Technology

There are many types of wearable devices available today.Different kinds of sensors provide strong technique support for acquisition of human physiological data.Flexible wearable sensors are lightweight,portable,low cost,and excellent in electrical performance.For example,artificial "electronic skin" combines various types of flexible sensors to sense external stimuli.The purpose of the artificial skin is to mimic the specific functions of human skin.This is very important for the development of intelligent robots.Tactile pressure sensing is one of the most important functions of electronic skin.Tactile pressure sensors are capable of quantifying the contact force between human body and the external environment,and then converting the contact force into an electrical signal.The development of wearable pressure tactile sensing tends to be miniaturized and specific.For example,a pressure sensor for fingertip touch can not only feedback the force on the fingertip,but also identify objects with different shapes and surface roughness.Firstly,this paper studies the application of a droplet-based capacitive flexible pressure sensor in the tactile perception of intraocular pressure.The sensor utilizes the sensing mechanism of the electric double layer capacitance at the contact of the electrode-electrolyte solution to achieve high-sensitivity capacitive pressure sensing.The sensor consists of a fully flexible material with a very simple construction.We applied this sensor to the intraocular pressure measurement of invitro pig eyes to verify the potential application of the sensor in the measurement of intraocular pressure.Secondly,in order to overcome the inconvenience caused by the external wires of the active device,we introduce the LC resonance component into the droplet sensing theory to realize the passive wireless pressure sensing device.The sensor has a capacitance of tens of picofarads,which greatly reduces the interference of parasitic capacitance and significantly enhances measurement accuracy.At the same time,the sensor has ultra-high sensitivity and excellent signal reproducibility,and is minimally affected by temperature.The geometry of the sensor is optimized to create a wearable device that can be worn at the fingertips and applied to the tactile perception of contact forces in motion mechanics.Finally,in order to expand the detection specificity of our wearable pressure tactile sensors and better simulate human skin,we designed a three-dimensional force sensor.The sensor is capable of detecting the force tangent to the sensor surface while measuring the normal pressure.The sensor includes four parallel plate capacitors.Because of the symmetry of the device,information of the normal and tangential forces can be obtained.At the same time,by introducing porous elastic materials working as the dielectric of the capacitor,the stiffness of our sensor decreases,which greatly improves the device sensitivity.