Research On High Performance Sensors Based On Graphene Reflection Coupling Structure

Graphene is a two-dimensional carbon material with hexagonal atoms.The thickness of single layer graphene was 0.334 nm,and the transmittance of light reached 97.7%.The interaction of graphene and light is weaker in the case of vertical irradiation,and it is difficult to achieve the requirements of the application device.Studies have shown that graphene has polarization dependence on light absorption under total internal reflection.By adjusting the layer number（thickness）,incident angle and polarization state of graphene,the absorption of light from 0%to 100%is no longer out of reach.In this paper,we enhance the interaction between light and graphene by total internal reflection（TIR）structure,and conduct research on high-performance sensors based on graphene reflection coupling structure.Not only that,through the regulation of refractive index,we found that polarization absorption enhancement is unusually sensitive to medium refractive index.Therefore,combined with the"lab on a chip"technology,the development of the sensor has provided a cutting-edge research idea.Refractive index sensing can be applied to biomedicine and analytical chemistry.In this paper,we will apply refractive index-based sensing in the following areas:1.Graphene-based ultra-sensitive pressure sensor-static detection.Reduced graphene oxide（rGO）is prepared by redox method,combined with reflection coupling structure,based on high-performance rGO glass and smart optical sensing system,an ultra-sensitive microfluidic pressure detection method has been developed.The detection limit and sensitivity of the microfluidic sensor are 1.4×10^-8 and 3.5×10⁹ mV/RIU respectively.The sensing system can detect the ultra-small water pressure of about 283 Pa caused by high-frequency ultrasound.2.Graphene-based ultra-sensitive flow rate detection-dynamic monitoring.High-quality graphene is prepared by an improved low-pressure chemical vapor deposition method.The microfluidic integrated graphene optical sensor realizes ultra-sensitive real-time monitoring of dynamic microfluidic flow rate.The sensitivity and detection limit of the sensors are 4.65×10⁵ mv·s^-1 and 4.9×10^-5 m·s^-1,and accurate measurements for ultra-low flow rates are achieved.3.Graphene-based mechanical wave detection-simulated arterial blood flow by peristaltic pump.We use a peristaltic pump system to simulate the heart pumping process,analyze the single pulse flow rate signal,and establish the relationship between flow rate and pressure.In the experiment,a peristaltic pump was used to simulate the blood supply process of the heart,and the sensor system monitored the flow rate.The frequency range of the peristaltic pump is 0.04-2.5 Hz,the flow velocity measurement range of the system is0.7-15 mm/s,the pressure measurement range is 0.6-14 kPa.This provides a new way to monitor extracorporeal blood circulation for medical treatment of special patients.