Research On Applications Of Self-powered Biosensors Based On Nanogenerator In Medical Signal Monitoring

As a new energy harvesting device,the nanogenerator can transform the distributed mechanical energy into electrical energy to continuously power wearable medical electronic devices.More importantly,the nanogenerator can also be used as a self-powered sensor to actively detect the static and dynamic processes caused by mechanical vibration with the output voltage or current signal,thus avoiding the inconvenience of medical electronic devices relying on battery power and realizing the intelligence of medical devices.Therefore,this paper mainly focuses on the mechanical energy harvesting and self-powered sensing characteristics of piezoelectric nanogenerator(PENG)and triboelectric nanogenerator(TENG),and aims to develop effective energy capture devices and sensitive self-powered biomedical sensors.The main research contents and achievements are summarized as follows:(1)Preparation and applications of PVDF/PDMS/CNT PENG.Utilizing PDMS as the matrix material,mixed with piezoelectric PVDF and conductive CNTs to prepare the PVDF/PDMS/CNT piezoelectric composite elastomer.Then,PVDF/PDMS/CNT PENG was designed by pasting copper electrodes in the two side of elastomer.The prepared PVDF/PDMS/CNT piezoelectric composite elastomer had superior mechanical strength and viscoelasticity.The piezoelectric performance test results showed that PVDF/PDMS/CNT PENG had very stable electromechanical conversion performance,and its output voltage increased with the increase of the content of PVDF and CNTs in the composite elastomer,the frequency of mechanical loading,and compression deformation,respectively.Application researches showed that the PVDF/PDMS/CNT PENG as an energy harvester could effectively collect the energy of mechanical vibration to light up the LED bulb;The designed self-powered smart insole could sensitively perceive the movement information of the human body such as walking,running and jumping.Based on this piezoelectric composite elastomer PENG,a hydrophobic intelligent artificial arterial tube was designed.Experiments showed that it had good blood pressure and blood flow frequency responsiveness,which had the potential of being implantable artificial blood vessels to realize the monitoring of heart rate and blood pressure of patients after surgery.Therefore,the prepared PVDF/PDMS/CNT PENG as a self-powered sensor shows potential application value in biomedical monitoring.(2)Preparation and applications of superhydrophobic liquid-solid contact TENG.A TENG substrate with a sandwich structure was prepared by using two pieces of double-sided tape to paste a fingertip structured copper electrode,then a layer of silica nanoparticles was deposited on the surface of the substrate to prepare a superhydrophobic liquid-solid contact TENG.The experimental results showed that the prepared superhydrophobic liquid-solid contact TENG had good flexibility and self-adhesiveness,and had super repulsive force to a variety of solutions including blood,and the contact angle is close to 160°.The electrical output performance results showed that the droplets of various solutions had sensitive current output when rolling on the surface of the superhydrophobic TENG,and the output current increased with the increase of the volume and height of the droplet respectively.The smart umbrella prepared based on superhydrophobic liquid-solid contact TENG could effectively collect the energy of raindrops;The prepared drainage bottle droplet sensor could monitor the drainage of the patient’s wound effusion in real time;The prepared tubular droplet counter has a function of precisely droplet counting.The simulated infusion experiment showed that the frequency of the current signal generated by the designed intelligent venous infusion set increaseed with the increase of the infusion speed,and could accurately monitoring the infusion operation.Therefore,the designed super-hydrophobic liquid-solid contact TENG with good flexibility,self-adhesiveness,super-repulsive effect of multiple solutions and sensitive electricity generation characteristics had shown potential application value in biomedical sensing.(3)Research on the applications of fabric TENG constructed by cellulose-based conductive macrofiber.Using BC as the matrix material,BC/CNT/PPy composite conductive macrofibers were prepared by wet drawing and wet twisting after physically doping CNTs and in-situ oxidative polymerization of PPy.The test results showed that the mechanical tensile strength and electrical conductivity of the BC/CNT/PPy composite conductive macrofibers reached 449 MPa and 5.32 S/cm,respectively.Degradation experiments showed that the BC/CNT/PPy composite conductive macrofibers could complete the degradation of the matrix material BC within 108 hours under the action of cellulase.The fabric TENG prepared by using BC/CNT/PPy composite conductive macrofibers as the electrode material had two working modes: contact-separation and single electrode.The fabric TENG in the contact-separation mode had a maximum output voltage of 170 V,a short-circuit current of 0.75 μA,and an output power of 352 μW under the action of mechanical force,which could successfully charge the capacitor and drive the operation of electronic devices.The fabric TENG in single-electrode mode could be used as a self-powered sensor attached to different parts of the human body to effectively monitor the movement of the human body.Therefore,the prepared fabric TENG had potential applications in the energy supply of electronic devices and human motion monitoring.In summary,this paper mainly prepared elastomer PENG,superhydrophobic liquid-solid contact TENG and fabric TENG,and used their self-powered sensing characteristics to design various biomedical sensors,such as smart artificial arterial tubes,drainage bottle drop sensors,tubular drop sensors,intelligent venous infusion detector and fabric motion sensors.These biomedical sensors could effectively monitor biomedical signals,and had shown potential application value in fields such as health care,intelligent medical treatment,and real-time monitoring of physiological signs.