Preparation Of Biomass Composite Gel And Its Research On Sensors

Flexible strain sensors have attracted wide attention because of their excellent performance.Material selection and structural design are two important factors driving the development of flexible strain sensors.Natural biomaterials have become a new star in the field of flexible and stretchable strain sensors because of their unique structure,diverse chemical groups,biodegradability and environmental friendliness.In this paper,the biomass composite gel was synthesized from cellulose,tannic acid and other materials,and the application of biomass composite gel in flexible and stretchable strain sensor was studied.Firstly,α-lipoic acid（LA）,Deep eutectic solvents（DES）prepared from choline chloride（Ch Cl）-acrylamide（AM）was used as raw materials to prepare poly LA-DES ionogel.A network structure including covalent bond,ionic bond and high-density hydrogen bond was formed,thus forming a stable ionogel.The prepared poly LA-DES ionogel shows super-stretching（>9000%）,100%ultraviolet blocking ability,adjustable rheological property and adhesiveness,ionic conductivity,anti-freezing and transparency.Because of its good coating ability,the ionogel can be coated on different substrates to assemble strain sensors.When poly LA-DES ionogel is injected into freeze-dried cellulose nanofibrils（CNF）aerogel,a solid gel with good responsiveness will be formed.Secondly,on the basis of poly LA-DES ionogel,cellulose（90μm）was introduced to solidify the liquid gel.The prepared cellulose gel shows good adhesiveness（the adhesion to glass reached 69.3 k Pa）,strong tensile property（2500%）and self-healing property（41%of the maximum stress in 10 s）.At the same time,the cellulose gel has good adhesion on substrates of different materials and shapes,and can be firmly adhered to human skin.The flexible strain sensor assembled based on cellulose gel can be used to monitor the change of relative resistance signal in different actions,and shows continuous and stable signal transmission performance.Finally,using tannic acid（TA）,acrylamide（AM）,acrylic acid（AA）and Fe³⁺as raw materials,poly（acrylamide-acrylic acid）/tannic acid-Fe³⁺hydrogel（poly（AM-AA）/TA-Fe hydrogel）was obtained based on dynamic redox catechol chemistry and iron ion regulation.The obtained hydrogel showed adjustable flexibility,good tensile strain（1500%）,adhesiveness and conductivity(4.45×10^-4 S/cm).The hydrogel is used to assemble primary batteries（the output voltage can reach 0.85 V）designed to provide power for small electric appliances or toys,and is used as a sensor to monitor the relative current changes of different actions,and to monitor various human movements in real time.This research will provide a promising strategy for the preparation of self-powered flexible strain sensors.