Magnetoelastic Sensitive Microfluidic Chip For Plasma Viscosity Measurement

Medical research shows that human plasma viscosity can be used for early diagnosis of some diseases.There is great important clinical significance.The conventional equipment is often not applicable due to its high cost and high sample volumes.It also needs professional operation and regular maintenance.Various MEMS-based resonating sensors have attracted great interest due to its high measurement precision and low volume liquid consumption.But,the fabrication of piezoelectric material based MEMS resonating sensor is complicated.Microcantilever which is one type of MEMS resonating sensor usually needs complicated optical equipment to detect the resonant parameters.This paper introduces a novel microfluidic chip based on magnetoelastic resonating sensor.The microfluidic chip is mainly comprised of four parts,namely,planar measurement coil,microfluidic system,sensor positioning slot layer and magnetoelastic sensor.The magnetostrictive material based magnetoelastic sensor is a wireless resonating sensor that is operated through magnetic fields completely and has a high quality factor in liquid.It is character with large measurement range.The planar coil is used to both actuate the sensor oscillation and detect the resonant frequency signal of the sensor.The planar coil can be fabricated by MEMS technology and integrated.Positioning slot layer was designed to fix sensor position.The microfluidic system was made of PDMS.The size of liquid chamber was designed according to magnetoelastic sensor.The planar coil and microfluidic system have been designed and fabricated.At last,the chip integration can be realized by simple bonding.Glycerol/water solutions with known densities and viscosities was measured by the microfluidic chip.The result shows that the chip works in large viscosity range.Meanwhile,the resonance frequency shift of the magnetoelastic sensors was measured using glycerol/water solutions with finely adjusted viscosities varying from 1.0cP to 3.0cP,which covers the viscosity range of blood plasma.The calibration curve of the sensor was obtained from the measurement results.On this basis,we measured the human plasma viscosity,which validated the feasibility to distinguish normal and abnormal human plasma viscosity with the proposed microfluidic chip.In addition,this paper investigated the effect of different resonance modes of magnetoelastic sensor to viscosity measurement.The Sample volume requirement is less than 100μL.The chip has realized the fast measurement.It is of great significance to the development of portable measurement technology in the future.