GMI Magnetic Bead Detection Technology Combined With Paper Chip

Magnetic bead detection technology has been widely used in the detection of magnetic beads,tumor markers,cells,bacteria,and microorganisms.This paper introduces in detail the magnetic bead detection technology based on the magnetic sensor and the practical application of the magnetic bead detection technology in the field of biomedicine.It focuses on the case of using the GMI sensor for magnetic bead detection and biological detection,and proves that the GMI magnetic bead detection technology have considerable application value in Magnetic beads,tumor markers detection and soon.Based on previous achievements and experience,this paper proposes to replace the traditional microfluidic chip with a paper chip as a separate detection tool,and combine the GMI sensor to establish a new type of magnetic bead detection technology to explore the feasibility of this technology in magnetic bead detection.The main research contents of the full text are as follows:1.By studying the output characteristics of the sensor to the unidirectional magnetic field,the output signal of the sensor has a linear relationship with the external magnetic field within the range of ±0.5Oe.The sensor has a good detection ability and the sensitivity is as high as 89V/Oe.2.This thesis specifically studied the five paper chip manufacturing processes:embossing method,pasting method,painting method,punching needle cutting method,and knife cutting method.The feasibility of the corresponding method is judged from the aspects of whether the actual area of the circular detection area of the paper chip is close to the theoretical area and whether the circularity value of the detection area is close to 1.Through the comparison of these five processes,it is determined that the paper chip produced by the die-cutting method has a high success rate,a standard detection area size,and can be mass-produced,and it is suitable as a separate platform for carrying magnetic beads.In this paper,the paper chip with filter paper as the base of the detection zone is called the three-dimensional paper chip,and the paper chip with the PVC film as the base of the detection zone is called the two-dimensional paper chip.3.Use three-dimensional and two-dimensional paper chips as the magnetic bead carrier for detection,and study the influence of the distribution of magnetic beads in different paper chips on the detection of magnetic beads.The results are as follows:(1)Study the influence of different external magnetic fields on the detection of magnetic beads.The results of using two paper chips to detect magnetic beads are similar: when the applied magnetic field is 0.5Oe,the sensor has the strongest detection ability;when the applied magnetic field is higher than 0.5Oe,the detection ability of the sensor decreases instead.This shows that the sensor's detection performance of the magnetic bead signal is determined by the strength of the magnetic bead's dipole field and the detection performance of the sensitive element under the action of an external magnetic field.When the applied magnetic field exceeds the anisotropy field of the magnetic sensor,even if the magnetic bead is more magnetized,the sensitivity of the sensor to the external magnetic field begins to decrease,resulting in the weakening of the magnetic bead signal collected by the sensor.(2)Study the influence of the diameter of the detection zone on the detection of magnetic beads.The detection results using the two paper chips as the magnetic bead carrier have something in common: when the diameter of the detection area is2 mm,the magnetic bead signal induced by the magnetic sensor is stronger than3 mm.This is because the detection zone with a diameter of 2mm restricts the magnetic beads to a space closer to the sensor,so the signal sensed by the sensor is stronger.(3)Use a two-dimensional paper chip as the detection platform,set the concentration of magnetic beads at 10pg/mL,and study the influence of different magnetic bead solutions on the detection of magnetic beads.The results show that when the amount is less than 7.5?L,the signal of the magnetic beads increases with the increase of the amount of magnetic beads;when the amount is higher than 7.5?L,the signal of the magnetic beads basically remains unchanged.This result is related to the phenomenon of magnetic bead clusters.The cluster phenomenon suppresses the dipole field enhancement effect of the high-density magnetic beads.(4)Study the influence of magnetic bead concentration on magnetic bead detection.The results of using different paper chips to detect magnetic beads are very different: the signal of magnetic beads in the three-dimensional paper chip first increases and then decreases with the concentration dilution,and the signal of the magnetic beads in the two-dimensional paper chip first decreases and then increases with the concentration dilution.This is due to the difference in the distribution of magnetic beads in the three-dimensional space of the paper fiber and the plane of the PVC film.