The Study Of A Self-Powered Flexible Electronic-skin For Visual-Image Recognition And Behavior Intervention

Human perceives the surrounding environment through methods of perception,including vision,olfaction,audition,tactility and gustation.With the development of wearable electronics,the emerging electronic-skin(e-skin)for detecting environmental changeor body activity has been extensively explored in recent years,such as the tactile e-skin.For realizing visual-image recognition,retina is a key film-shaped tissue behind the vitreous-body,which directly detecting light and outputting/transmitting bioelectricity signal to the nervous system.In future medical care,the vision e-skin as artificial retina integrated with the human body may play an important role in vision reparation or expansion,such as helping blinds re-see the blue sky or high-risk workers see the ultraviolet.At present,some research groups have reported various flexible photodetecting electronics.The general idea of the device design is constructing an integrated flexible system including photodetector array,information analyzer,signal transmitter and electricity power unit.The complex integrated units in the system raise the production cost and bring difficulty in its promotion/extending.A battery-free or self-sustainable vision e-skin may have potential application in synthetic eye and artificial intelligence with low-cost and long-term utility.Another problem is to input the photodetecting signal into the brain for participating in the vision perception and relevant behavior intervention.A new self-powered brain-linked vision electronic-skin(e-skin)for mimicking retina has been realized from Ppy/PDMS triboelectric-photodetecting pixel-addressable matrix.The e-skin can be driven by human motion,so no external electricity power is needed in both photodetecting and signal transmitting processes.Specific studies are as follows:(1)Fabrication of a self-powered flexible vision e-skin:In the fabrication procedure,standard photolithography,printed circuit board technique,PDMS soft-template method,electron beam evaporation process,and electrochemical polymerization are successively exploited.A flexible PDMS film(4 cm×3.5 cm×0.5 cm)treated by inductively coupled plasma method acts not only as flexible substrate of the device but also as the negative triboelectric material.On the top side of the PDMS film,a patterned Cu network located in the groove of PDMS is applied to support Ppy and works as top electrode.On the other side of the PDMS film,there is a whole Cu back electrode(thickness=100 nm)for collecting the current signal.The top Cu electrode is inlaid in the PDMS film,and Ppy is deposited on the copper by electrochemical workstation.Conducting polymer Ppy plays an important role in the e-skin because it is both the triboelectric and photodetecting material.(2)Illumination detecting:The triboelectric output of the e-skin is significantly dependent on the photo illumination,which can act as visual bionic electric impulse.Taking blue illumination(405 nm)as an example,as the e-skin is exposed to 100 ?W cm-2 blue illumination,the output current decreases from 7.5 to 4.9 nA,and the response is 34.3%.And the response of the e-skin keeps stable with different bending angles and force.The e-skin is flexible enough to combine with human body and can be driven by blinking eyes to detect UV illumination.In addition,the 4×4 photodetecting unit matrix in the e-skin can map single-point and multi-point illumination-stimuli(visual-image recognition)via the multichannel data acquisition method.(3)Biological perception involvement and behavioral intervention:We implante vision electronic skin into mouse brain's primary motor cortex(M1).The triboelectrical stimulation which depends on external light stimulation can be treated as the afferent impulse,and then the brain can use this information to analyze,decode,and deliver behavioral photoresponse.As the devices are slapped,the mouse's tail rapidly uplifts and falls.If the triboelectric stimulus is small(the devices are under UV illumination),the mouse keeps statically.Therefore,this new type of vision electronic skin realizes biological perception participation and behavioal intervention,which has a great promotion effect on implantable devices such as bionic retina.