Design Of Soft Materials Based E-Skin Sensing Systems

Recently the skin-like sensors made of flexible and soft materials have shown great potential in several applications such as wearable devices,soft robotics,health detecting systems and artificial prosthesis.Owing to their excellent sensing performance and human affinity,they are usually called “e-skin”.With this kind of eskin,we can quantize the complex movements and contact with objects of our hands,which shows promising potentials for safe human-machine interaction.Currently,the challenges in the e-skin systems lie in the improvement of sensitivity,the decrease of thickness,the increase of transparence and the diversity of functions,on which we address to develop the e-skin sensing system in this thesis.In Chapter 2 carbon grease is applied as the soft electrode to fabricate a resistive type filmy strain sensor.The sensor has the thickness less than 0.5mm,47~90% thinner than the existing works,with a high sensitivity of 8.Then,an e-skin system is integrated with 5 sensors to measure the American digit sign language.Machine-learning method is also combined to verify its practicability of the gesture identification.Supported by the experimental data from different subjects,our e-skin system succeeds in identifying American sign language 0–9 with an average accuracy of 98%.In order to solve the shortcoming that the e-skin based on carbon grease in Chapter 2 is not transparent,in Chapter 3 a new ionic hydrogel,is introduced as replacement of carbon electrode.With the ionic conducting hydrogel,a totally transparent resistive strain sensor with good performance is obtained.Therefore,a transparent resistive eskin system containing 10 sensors is integrated with the wireless transmission module,and the verification of more complex sign language is implemented.In Chapter 4,to make the e-skin system with the touch sensing function,ionic hydrogel is also used to manufacture a capacitive type tactile sensor to detect the pressure of fingertip.A series of basic performance tests are conducted and the excellent linearity of this sensor is proved.Combining with graphical display through Matlab,the tactile sensors demonstrate great practicability in daily life applications.