The Study Of The Fabrication/Characterization/Application Of The Lignin-based Piezoresistive Sensor

Piezoresistive sensor can convert force signal to electrical resistance signal.It's widely used in the information technology,electronic engineering and mechanical engineering.Traditional piezoresistive sensor are usually fabricated by metal or silicon,these materials are hard to naturally degradation and will bring about massive problems in environmental protection accompanied by other pollutions such as water and soil pollution.With the widely application of electronic devices,the non-degradable and heavy-metal pollution problems has drawn people's attention.Based on lignin,a green environmentally friendly recyclable biomass,we fabricated a carbon array through direct laser writing carbonization(DLWc)technology.By utilizing the piezoresistive characterization of carbon materials,a biomass-based carbon array force sensor is efficiently fabricated.Through using the theory of the piezoresistive,converting humidity signal to force signal,the force sensor is successfully applied to detecting humidity.The specific topics are listed below:(1)Through water solution cast,a soft crack-free lignin film with controllable thickness is fabricated on the PET substrate.Different conductive carbon line is fabricated through the DLWc of lignin film at different laser power.Raman spectroscopic,XPS,FTIR and SEM is also performed to characterization the morphology and structure of the DLWc carbon of lignin.This work laid the foundation for the following research of the manufacturing-structure-property of the DLWc carbon sensor.(2)Piezoresistive sensor is fabricated through the DLWc of lignin film.Multiscale modeling structure is also changed through changing the laser power of DLWc.Dynamic mechanical analyzer/digital multimeter system is applied to investigate the response of the lignin sensor to strain.Through using the multi-level structure design method,a line-line contact area sensor(LLAS)with higher sensitivity is also successfully fabricated.Long term stability test is also applied to investigated its possibility in practical application.The result shows that compared to PLS sensor,multi-level structure designed LLAS sensor effectively improved the stability of the DLWc lignin sensor,and gives a guarantee in the quality of the produced sensor.(3)Humidity sensor is fabricated through the DLWc of lignin film.Different humidity sensor is also fabricated through changing the laser power of DLWc.DMA with humidity accessories together with DMM is applied to investigated the response of resistance of humidity sensor to humidity change.The laser effect of laser power to humidity response was studied through performing cyclic test and stage stability test.The humidity sensor shows a consistency response to the humidity with the humidity change.The mechanism of humidity sensor is explained by combining the FTIR and XPS result of the DLWc carbon line.This new kind of process to fabricate humidity sensor will surly bring about new mind to sensor manufacturing.