A Silver Nanowire Flexible Strain Sensor Based On Photopolymerized-ultrasonic Pattern Enhancement

Silver nanowire flexible strain sensors have wide applications,and the silver nanowire flexible strain sensor with in-plane structure has become one of the most popular research topics because of its advantages of thin thickness,light weight,high transmittance and flexibility.However,the existing studies on silver nanowire flexible strain sensor with in-plane structure have defects like low sensitivity(Gauge Factor,GF < 30)and insensitive to tiny strain detection.Through patterning silver nanowire flexible strain sensor,the sensitivity can be greatly improved.However,the existing patterned silver nanowire film preparation processes have some shortcomings such as:(1)Precision laser slicing machine;(2)expensive customized molds;(3)Toxic chemical reagents.To solve the above problems,we propose a novel preparation process of patterned conductive film with the self-made photopolymerization formula as the adhesive and photoresist to achieve the photopolymerized-ultrasonic patterned silver nanowire conductive film.After obtaining the optimal preparation conditions through optimized experiments,the patterned preparation process will be applied to silver nanowire flexible strain sensor,and a silver nanowire flexible strain sensor based on photopolymerized-ultrasonic pattern enhancement will be achieved.Then the enhancement effect of different patterns on the flexible strain sensors will be explored.Finally,the sensor will be applied to detect the movement of human epidermis.The specific research work of this paper is summarized as follows:(1)The preparation process of photopolymerized-ultrasonic patterned silver nanowire conductive film.The preparation process of photopolymerized and ultrasonic patterned flexible silver nanowire film was optimized in terms of three factors: photopolymerization formula,exposure time and ultrasonic time.The highest integrity(99.1%)and the lowest residue(0.92%)silver nanowire film pattern was obtained by using photopolymerization formula II,180 seconds exposure and 90 seconds ultrasonic treatment.The silver nanowire pattern with a minimum linewidth of 30 ?m was obtained under the optimal experimental conditions.Finally,profile scan of the silver nanowire film pattern showed that the average thickness of the silver nanowire film pattern was 1.6 ?m,and the silver nanowire in the film pattern was distributed evenly,which proved that the photopolymerized-ultrasonic patterned flexible silver nanowire film preparation process had great stability.(2)The enhancement effect of patterning design on the performance of silver nanowire flexible strain sensor.The preparation process of photopolymerized-ultrasonic patterned flexible silver nanowire film was applied to flexible strain sensor with patterned in-plane structure,and a silver nanowire flexible strain sensor based on photopolymerized-ultrasonic patterned enhancement was achieved.Then,the electromechanical properties of the flexible strain sensor with different pattern structures,length and linewidth parameters was tested.The results showed that the silver nanowire flexible strain sensor with linear structure,60 ?m linewidth and 8 mm length had the best sensitivity.The sensitivity of the sensor reached 10486.7 at 8% stretching range.Besides,response and stability of the flexible strain sensor were tested.Sensor showed quiet response that less than 20 ms and great stability under 4800 repeated tensile.The transmittance of the sensor is over 80% in the visible light transmittance test.The sensor was applied to monitor human pulse and laryngeal node movement successfully.