Magnetic Sensor With Gradient Protective Layer for Biomolecule Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional biosensors face challenges in accurately detecting biomolecules, especially at low concentrations, due to variations in detection results caused by the removal of biomolecules and magnetic beads, which affects the resistance value change of the magnetoresistive effect element.
Innovation Solution
A magnetic sensor with a magnetoresistive effect element configured in a linear shape on a substrate, featuring a protective layer with a thicker top surface layer and a thinner side surface layer, allowing for enhanced biomolecule capture and detection, and a magnetic detection system that applies a magnetic field to generate a stray magnetic field from magnetic beads for accurate biomolecule detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gradient magnetic field or washing is applied to remove excess biomolecules and magnetic beads, then the detection process can proceed, but biomolecules and magnetic beads are removed from the protective layer causing insufficient resistance value change and large variations in detection results
Solution Approach 1:
The protective layer is designed with a thickness gradient in the vertical dimension, being thicker at the top surface and thinner at the side surface. This dimensional variation allows the top surface to retain biomolecules and magnetic beads during washing, while the thinner side surface still permits magnetic field penetration for detection, thus resolving the contradiction between retaining substances and enabling detection.
Solution Approach 2:
Different regions of the protective layer are given different thicknesses to serve different functions: the top surface has greater thickness to retain biomolecules and magnetic beads, while the side surface has lesser thickness to allow magnetic field penetration. This local differentiation resolves the contradiction by optimizing each region for its specific purpose.
2Reliability
If the protective layer is made thicker to retain more biomolecules and magnetic beads, then detection accuracy improves, but magnetic field penetration and resistance value change may be insufficient
Solution Approach 1:
The protective layer thickness is varied in the vertical dimension, creating a gradient structure. This allows the top surface to be thick for retention while the side surface remains thin for magnetic field penetration, thus resolving the contradiction between retention capacity and detection sensitivity.
Solution Approach 2:
The protective layer is designed with non-uniform thickness where different regions serve different functions: thicker regions for retention and thinner regions for magnetic field penetration. This local quality differentiation resolves the contradiction by optimizing each region's thickness for its specific purpose.
3Ease of operation
If washing is applied to remove excess biomolecules, then the detection process continues, but variations in detection results become large especially for low biomolecule concentrations
Solution Approach 1:
The thickness gradient in the vertical dimension allows the protective layer to retain biomolecules and magnetic beads during washing operations. The thicker top surface prevents removal during washing, thereby reducing detection result variations while maintaining ease of operation.
Solution Approach 2:
The protective layer's non-uniform thickness provides localized retention capability during washing: the thicker top surface retains biomolecules and magnetic beads during the washing process, reducing detection variations while allowing the washing operation to proceed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The configuration enables high-accuracy detection of biomolecules by facilitating their capture and reducing variations in detection results, particularly in samples with low biomolecule concentrations, by maintaining the biomolecules and magnetic beads on the protective layer.
Implementation Method 1
a magnetoresistive effect element, the resistance value of which changes in accordance with an input magnetic field
Implementation Method 2
magnetic beads having an affinity for biomolecules in samples are captured on a protective layer via the biomolecules, a stray magnetic field is generated from the magnetic beads
Data Source
AI summary
A magnetic sensor includes a substrate having a first surface and a second surface, which is opposite the first surface, and a detection unit provided on the first surface. The detection unit includes a magnetoresistive effect element, the resistance value of which changes in accordance with an input magnetic field, provided on the first surface, and a protective layer that covers at least the magnetoresistive effect element. The magnetoresistive effect element is configured in a linear shape extending in a first direction on the first surface. The detection unit has a first width, which is a length in a second direction, orthogonal to the first direction, and a second length, which is greater than the first width. The first width is the length of the detection unit on the first surface, and the second width is the length of the top surface of the detection unit.