Biosensor Using Double Pass Light Transmission for Magnetic Particle Detection
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Solution Overview
Problem
Existing biosensing methods using magnetic nanoparticles are complex, costly, and require specific optical elements or large electromagnets, limiting their practicality and sensitivity for detecting target analytes.
Innovation Solution
A compact, flexible, and inexpensive biosensor utilizing a suspension of magnetic particles with an oscillating uniaxial magnetic field and a light source, where light intensity is modulated and measured after passing through the particles multiple times, allowing for sensitive detection without the need for polarized light or large electromagnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light polarization rotation is measured to detect analytes, then detection sensitivity is improved, but device complexity and cost increase due to requiring aligned polarizers and optical elements
Solution Approach 1:
The invention extracts and eliminates the complex optical elements (polarizers, aligned optical components) from the detection system while retaining the core detection function through a simplified light intensity modulation approach that measures analyte-induced changes without requiring polarization measurement
Solution Approach 2:
The invention uses a simplified optical measurement approach that copies the essential detection principle (measuring light interaction changes) without requiring the full complexity of polarization rotation measurement, achieving comparable sensitivity through intensity modulation alone
2Ease of operation
If electromagnets generating rotating magnetic field are used, then magnetic particle manipulation is improved, but device size increases limiting practical applications
Solution Approach 1:
The invention replaces the mechanical electromagnet system with a permanent magnet, eliminating the need for electrical power and complex control while maintaining effective magnetic field generation for particle manipulation
Solution Approach 2:
Instead of using an active electromagnet system that generates magnetic fields through electrical current, the invention inverts the approach by using a passive permanent magnet that provides the necessary magnetic field without requiring power supply or complex control electronics
3Measurement precision
If scattered light at large angle is measured, then magnetic bead detection is improved, but signal intensity becomes extremely low requiring large area photodetectors
Solution Approach 1:
The invention changes the measurement dimension from large-angle scattered light detection to forward-transmitted light intensity measurement, achieving equivalent detection sensitivity with significantly higher signal intensity using a compact photodetector
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 biosensor achieves sensitive and cost-effective detection of target analytes by modulating light intensity through a compact setup, suitable for various devices and applications, including diagnostic purposes, with flexible options for light sources and particle properties.
Implementation Method 1
a magnetic field generation unit generating an oscillating uniaxial magnetic field... whereby the suspension of magnetic particles is modulated such that the intensity Itrans of light transmitted through the suspension of magnetic particles is modulated
Implementation Method 2
light from the light source and the oscillating uniaxial magnetic field is propagating substantially parallel along an incoming direction... light transmitted through the optical reservoir has an intensity Itrans... measuring the intensity Itrans of the light transmitted through the suspension of magnetic particles after the light has passed through the optical reservoir at least two times
Data Source
AI summary
Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample. The setup may be implemented in a disc and optical pick-up head configuration.