Home > News > Advanced functional materials: Based on Cassie Baxter surface construction technology, the design strategy of wearable flexible strain sensor against liquid interference and bacterial adhesion is realized

Advanced functional materials: Based on Cassie Baxter surface construction technology, the design strategy of wearable flexible strain sensor against liquid interference and bacterial adhesion is realized

wallpapers News 2020-09-15

wearable flexible electronic strain sensor has been gradually put into the fields of daily consumer products medical health industry military. In the future wearable flexible electronic strain sensor will be more challenging promising. It will continue to integrate innovate with electronic health artificial intelligence biochip big health cloud data other strategic emerging industries which need to tackle key problems The technical problem is not only the upgrading breakthrough of sensing performance such as ultra sensitivity wide strain sensing range of flexible devices. In order to realize the technology integration application in many fields the wearable flexible electronic strain sensor needs to resist liquid interference in complex operating environment stable sensing operation is an important scientific problem to be solved. Because the complex environment (such as water acid alkali salt microorganism etc.) will interfere with the flexible strain sensor resulting in the instability of electrical properties such as conductivity thus affecting the stability of the flexible strain sensor shortening its service life. For example if bacteria adhere to the surface of the sensor it will produce microbial corrosion damage the conductive layer. If water molecules or other molecules infiltrate into the conductive layer it will not only affect its electrical performance but also produce fouling. The traditional technology to avoid liquid interference is to encapsulate the sensor with polymer but it has some disadvantages such as poor sensing performance complex packaging process. Therefore a scientific hypothesis is put forward to construct Cassie Baxter wetted state directly on the surface of wearable flexible electronic strain sensor without encapsulation so as to realize anti droplet sensing interference reveal its internal mechanism which has important research significance.

research team of Associate Professor Lin Jing of Guangzhou University found that: MWCNT / g-pdms wearable flexible electronic strain sensor based on Wenzel surface wetting state is very vulnerable to external liquid interference in the sensing process. Combined with the experimental data Wenzel surface wetting state liquid interference model analysis we know that the liquid will have the phenomenon of infiltration the conductive path changes the resistance decreases The sensitivity of tensile sensor is decreased the tensile range is limited. Through the analysis of surface wetting theory the reason is that the Wenzel wetted flexible sensor does not have super hydrophobic underwater oil repellent self-cleaning antifouling other properties. It is easy to adhere to water or oil droplets but also easy to adhere to bacteria which makes its electrical performance vulnerable to the interference of various liquids.

Aiming at the scientific problem that the unsealed strain sensor is easy to be interfered by external liquid in the tensile sensing process the research team of

Associate Professor Lin Jing of Guangzhou University proposed a strategy for the first time to realize the anti liquid interference anti bacterial adhesion of the sensor based on Cassie Baxter surface construction technology The key technology theory of liquid interference anti-bacterial adhesion. The technological innovation of

lies in the swich like structure of the sensor structure the bottom layer is a flexible substrate of hyperelastic polydimethylsiloxane (PDMS) the middle layer is a LBL type carbon nanotube / graphene (MWCNT / g) conductive sensing layer (aminopropyl) triethoxysilane (APTES) bonding layer the outer layer is a modified silver nanoparticles fluorination layer. The multi-level structure surface design of F / Ag / MWCNT / g-pdms (famg) sensor realizes the transition from Wenzel to Cassie Baxter It is difficult to overcome the "water barrier" of the sensor because the contact angle between the surface of the air cushion the surface of the air cushion is about 0 ° the contact angle between the surface of the air cushion the surface of the oil droplet is about 4 ° the contact angle between the surface of the air cushion the surface of the water droplet is about 0 ℃( Green tea black tea orange juice cola milk acid (pH = 1) alkali (pH = 10) salt (0.4 mol / L) bacterial droplets (104 CFU / ml) has good anti adhesion anti-interference properties. Its surface has superhydrophobic underwater oil repellent self-cleaning antifouling anti bacteria adhesion other properties. After 1000 stretch retract cycles the sensitivity of the wearable flexible electronic strain sensor is as high as 1989 in the case of liquid interference it has a wide tensile sensing test range (0.1-170%) fast response ability( The response recovery time is 150ms) which shows excellent sensing performance stable anti-interference performance. In the artificial rainfall test the famg wearable flexible electronic sensor which monitors the movement behavior of the electronic bird has strong resistance to liquid interference bacterial adhesion tests the movement behavior of all parts of the human body (pulse wrist finger knee). It realizes the omni-directional accurate monitoring of human activities in complex environment which shows that the sensor has good performance in complex environment Good adaptability.

The theoretical innovation of

is to put forward the design strategy of anti liquid sensing interference reveal the internal sensing mechanism of the new multi-stage structure ultra sensitive wide range strain sensor. It is revealed that the crack propagation effect of MWCNT / g conductive layer the terminal crack propagation effect of APTES / MWCNT / g intermediate isolation layer are the internal mechanisms of producing ultra sensitive. The micro bridge effect of MWCNT the interval effect of APTES / MWCNT / g intermediate isolation layer are the internal mechanisms of producing ultra sensitive The slip effect of the separation layer is the main internal reason for the wide application range of tensile sensing. The construction of multi-stage Cassie Baxter surface wetting state is the key technical theoretical basis for anti-interference of liquid sensing. Superhydrophobic underwater hydrophobic wetting characteristics are the internal mechanism of anti-bacterial adhesion. The relevant achievements of

were published online on advanced functional materials with the title of "anti ‐ liquid ‐ interacting bacterial antiadhesive strategy for highly stretchable ultra sensitive strain sensors based on case ‐ Baxter wetting state"( DOI:10.1002/adfm.202000398 )Associate Professor Lin Jing of Guangzhou University is


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