Novel Surface Acoustic Wave Sensor And Microfluidic Device Applied In Health Care

With the rapid development of science and medical treatments,the average life span of human has greatly increased,and China will inevitably enter the aging society.Early diagnosis of diseases and real-time health monitoring will become particularly important in the future.Existing medical testing instruments are very large,expensive,and are not suitable for ambulatory monitoring at home.Therefore,miniaturized,portable,and wearable medical testing instruments have great development prospects in the field of medical health.Sensors are the core electronic units in medical testing instruments.They can convert the analog quantity in the environment into observable digital quantities.The development of high-performance,miniaturized sensors is a current research hotspot.In recent years,the surface acoustic wave?SAW?devices have received much attention in the field of sensing.Compared with traditional sensors,SAW sensors have the advantages of small size,high sensitivity,low cost,low power consumption.And SAW device can be used as a passive wireless sensor,which is very suitable for use in the medical health field.SAW devices can also be used in microfluidic for precise manipulation,sorting,patterning,and pumping of cells,and have great application prospects in the tissue engineering and regenerative medicine fields.The applications of novel SAW devices in the medical health field were explored and investigated,and the paper mainly includes two aspects:1.Small and wearable novel SAW sensors;2.SAW microfluidic devices.Two types of SAW sensors have been fabricated and assessed for monitoring respiration that is suitable for anOSAS monitoring application.One is on a flexible ZnO/PI and another is on a Li NbO3 bulk substrate.First,two kinds of SAW sensors were used for wired measurement.The response time and recovery time of the Li NbO₃SAW sensor were 1.86 s and 0.75 s,respectively and that of the flexible SAW sensor were 1.125 and 0.75 s,respectively.The sensitivity of Li NbO₃ SAW and flexible SAW sensors is approximately 2.7 MHz/50%RH?caused by surface condensation?and 0.36MHz/50%RH?caused by humidity changes?.The Q of Li NbO₃ SAW sensor is 18600,which is further used for wireless passive respiration monitoring.The SAW sensor was glued onto a flexible antenna,and then attached on the upper lip of the volunteer.Because the Q of the sensor is not high enough and the antenna is not perfect,only short distances of stable measurements can be achieved.But the distinction between the test results ofOSAS and normal breath was obvious.We also fabricated and assessed ZnO/Al flexible SAW UV sensors with different wavelengths,and the wave mode corresponding to each resonant peak was determined by COMSOL simulation.In order to minimize the effect of temperature,the mode with the smallest TCF?A0 mode,100?m?was selected for spin coating the sensing layer.The sensing layer is 3D T-ZnO MNs material,which has extremely high pore density?up to 98%?,large surface-to-volume ratios,and stable chemical/physical properties.The UV sensitivity of the SAW sensor is increased from-3.03×10^-6 to-5.25×10^-6cm²m W^-1 with the application of a T-ZnO MN layer.At the same time,we bend a flexible SAW UV sensor with a wavelength of 400?m at different angles,and test the UV characteristics of the device under different strains.In addition,the measured sensitivity to the UV intensity is demonstrated to be significantly modified under bent conditions.For the application of microfluidics,we realized microparticle patterning and 3D manipulation of yeast cells inside a chamber with a height of 1 mm using thin film ZnO/Si SAW devices.We systematically investigated the effects of standing SAW?SSAW?frequency on 3D line patterns.We have also achieved precise position control of the microparticles in the direction of SAW propagation by changing the phase angles of the SAW.It is an important biomedicine-related application in microarrays,tissue engineering and regenerative medicine.In addition,a numerical model has been developed to investigate the SAW acoustic field and the 3D motions of microparticles under the acoustic radiation forces within a microchamber.