Piezoelectric-enzymatic Reaction Coupling Effect Based On GaN And Self-powered Biosensor

With the development of science and technology,a variety of new electronic skin is emerging.As a new type of sensor,wearable electronic skin may change the traditional medical model.In recent years,the electronic skin developed by people is mainly used to detect human movement and physiological indicators.Human blood contains a lot of biological information.CRP(C-reactive protein)is a special protein in human body.Real-time detection of CRP can effectively prevent and diagnose chronic inflammation such as cardiovascular disease.Although there are many devices that can measure CRP in the body,these devices usually require an external power source,and bulky batteries are not easy to wear.In order to meet the needs of long-term implantation,wearable biosensing electronic skin should have good biocompatibility.In order to better fit the human body,the wearable electronic skin should be soft and flexible.In order to eliminate the trouble of electronic skin frequently replacing the power supply in the human body,the wearable electronic skin should be able to be converted into electrical energy by the mechanical energy generated by the human body motion to maintain its own power supply.In order to further develop wearable biosensor electronic skin,a self-sustaining device without external power supply may have potential applications in low-cost and long-term medical care.In this paper,based on the piezo-biosensor coupling effect of GaN nanowires,a novel self-powered electronic skin for detecting CRP level in body fluids is proposed.The flexible device can work in liquid and measure CRP concentration in real time without any external power supply.The piezoelectric output generated by GaN nanowires can not only be used as the electric energy of the driving device,but also as the biosensor signal to detect the content of CRP.This research result can provide a new material system for the next generation of self-powered wearable biosensors.The specific contents are as follows:(1)Self-powered electronic skin was prepared by simple chemical vapor deposition method and micro-machining technology.In the first step,a GaN nanowire array is prepared by chemical vapor deposition.First,a 5 nm Au layer was evaporated onto a sapphire substrate by electron beam evaporation,and then a gallium nitride nanowire array was prepared using high purity Ga2O3 and ammonia as a precursor.In the second step,a lithographic pattern is formed on a Kapton plate coated with GaN nanowires by photolithography,and then a titanium electrode is evaporated on the lithographic pattern by a vacuum coating technique.In this process,the thickness of the titanium electrode is 1 μm,the length of gallium nitride is about 6 μm,the distance between the two pairs of electrodes is 4 μm,and the distance between two identical electrodes is 10μm.The purpose is to ensure that the gallium nitride nanowires can be placed on the electrode pairs during laying,and it is also possible to prevent the gallium nitride nanowires from being short-circuited on the same electrode and short-circuited.In the third step,the device is immersed in an acetone solution and washed with deionized water to remove the portion containing the photoresist.In the fourth step,the C-reactive protein antibody is dropped on the surface of the sensing unit and dried at room temperature.Four times,and rinse off the firm antibody to the device junction with deionized water.(2)The concentration of CRP antigen in the self-powered CRP electronic skin detection solution.When the electronic skin was placed in a solution containing CRP antigen,the output voltage signal decreased as the concentration of CRP antigen increased.(3)The working mechanism of self-powered CRP electronic skin piezo-biosensor coupling effect.In the sensing process of CRP,the specific binding of CRP antigen antibody will affect the carrier density on the surface of gallium nitride nanowires,thus affecting the piezoelectric output.The voltage output can directly reflect the concentration of CRP antigen in the solution.(4)The Study of self-powered CRP electronic skin for detection of CRP concentration in blood of normal rabbits and fever rabbits.We placed the electronic skin in the blood of the fever rabbit and the normal rabbit separately.The stepper motor controls the hammer to apply a stable periodic external force to the electronic skin.The electronic skin deforms under the external action,thereby generating the piezoelectric voltage.The self-powered electronic skin can measure the concentration of CRP in the blood of rabbits in real time.The output voltage of the electronic skin in the blood of two kinds of rabbits is different,which can easily diagnose the occurrence of inflammation and timely administer drugs,thus minimizing the risk of inflammation.