Magnetic Biosensor Differential Detection via Insulator Thickness Variation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic-field biosensors face challenges in accurately detecting magnetic nanoparticles attached to biological materials due to interference from externally applied magnetic fields.
Innovation Solution
The proposed magnetic-field biosensor incorporates a substrate with multiple magnetic-field sensing elements, an insulator with varying thicknesses, and receptors configured to attach to biological materials. The biosensor uses a differential output from pairs of magnetic-field sensing elements, one with a receptor and one with a deterrent layer, to detect magnetic nanoparticles while mitigating the effect of applied magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single magnetic-field sensing element is used to detect magnetic nanoparticles, then the device structure is simple, but the detection accuracy is reduced due to interference from externally applied magnetic fields
Solution Approach 1:
The sensor is divided into multiple sensing elements (first and second magnetic-field sensing elements) with different insulator thicknesses. Each element experiences different magnetic field conditions, allowing differential measurement that cancels out common-mode interference from externally applied magnetic fields while preserving nanoparticle detection capability.
Solution Approach 2:
Different regions of the sensor have different insulator thicknesses (first plurality of portions with first thickness, second plurality of portions with second thickness). This creates local variations in magnetic field exposure, enabling the first sensing element to detect both applied field and nanoparticle field, while the second element detects primarily the applied field for subtraction.
2Measurement precision
If the insulator thickness is uniform across all sensing elements, then the manufacturing process is simple, but the ability to differentiate between applied magnetic field and nanoparticle magnetic field is reduced
Solution Approach 1:
The insulator is designed with deliberate local thickness variations - first plurality of portions have first thickness and second plurality of portions have second thickness. This controlled non-uniformity creates the necessary differential magnetic field exposure to enable field differentiation, while the thickness values remain within manufacturable ranges.
Solution Approach 2:
The insulator thickness parameter is intentionally varied between different regions of the sensor. By changing this geometric parameter, the magnetic field shielding effect is modulated, allowing the sensing elements to experience different field conditions necessary for differential measurement and interference rejection.
3Measurement precision
If magnetic-field sensing elements are directly exposed to externally applied magnetic fields, then the signal strength from magnetic nanoparticles is enhanced, but the interference from the applied magnetic field increases
Solution Approach 1:
Different sensing elements have different insulator thicknesses creating local variations in magnetic field exposure. The first sensing element experiences stronger field (both applied and nanoparticle), while the second experiences primarily applied field, enabling differential measurement that enhances nanoparticle signal while rejecting interference.
Solution Approach 2:
The externally applied magnetic field, which is normally a harmful interference, is converted into a useful reference signal. By having one sensing element primarily detect the applied field and another detect both applied field and nanoparticle field, the applied field becomes part of the measurement that can be mathematically subtracted, leaving only the nanoparticle signal.
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
This configuration allows for improved detection of magnetic nanoparticles by reducing the impact of externally applied magnetic fields, enhancing the sensitivity and accuracy of the biosensor.
Implementation Method 1
Each of the magnetic nanoparticles generates a magnetic field. For example, the magnetic nanoparticle 124a generates a magnetic field 128a.
Implementation Method 2
The magnetic nanoparticles collectively behave like a super paramagnet and are configured to align with an externally applied magnetic field 120.
Data Source
AI summary
In one aspect, a magnetic-field biosensor includes an insulator and a plurality of magnetic-field sensing elements that includes a first and a second magnetic-field sensing elements. The insulator has a first and a second plurality of portions, and the second plurality of portions is thicker than the first plurality of portions. The magnetic-field biosensor further includes a first receptor configured to attach to biological material and being on a first portion of the first plurality of portions and directly above the first magnetic-field sensing element; and a second receptor configured to attach to the biological material and being on a first portion of the second plurality of portions and directly above the second magnetic-field sensing element. Outputs of the first and the second magnetic-field sensing elements are used to sense a magnetic field from a first magnetic nanoparticle by reducing an effect of an applied magnetic field.