Optical Waveguide Biosensing With Magnetic Particle Field Cycling
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Solution Overview
Problem
Existing wearable biosensors, such as continuous glucose monitors, are limited in their ability to detect analytes other than glucose and require invasive sampling or bulky lab equipment, failing to meet the demand for low-cost, wearable devices capable of monitoring a wide range of analytes like proteins and small molecules present in interstitial fluids.
Innovation Solution
A device for optical biosensing using magnetic particles, comprising an optical waveguide with tethered magnetic particles, a magnetic field generator, and a capture reagent, which alters the position of magnetic particles within the evanescent field to detect analytes based on output signal changes, utilizing a receiver module for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic particles are tethered close to the waveguide surface, then the sensing sensitivity is improved, but the magnetic field cannot effectively actuate the particles
Solution Approach 1:
The patent uses dynamically adjustable tether lengths that can be controlled via magnetic field application. The tethers allow magnetic particles to transition between extended positions (when magnetic field is applied) and retracted positions (when magnetic field is removed), enabling the system to dynamically adapt the particle-wa g e g u i d e distance based on operational requirements
Solution Approach 2:
The patent introduces an additional spatial dimension by using tethered magnetic particles that can extend perpendicular to the waveguide surface. This vertical dimension allows particles to be positioned at optimal distances for both magnetic actuation and optical sensing, resolving the trade-off between magnetic field penetration depth and evanescent field interaction strength
2Measurement precision
If magnetic particles are held within the evanescent field for detection, then the signal strength is improved, but the ability to perform repeated measurements is reduced
Solution Approach 1:
The patent implements periodic cycling of magnetic field application to alternately hold and release magnetic particles. This periodic action enables repeated measurements by resetting the particle positions between measurement cycles, allowing the same particles to be used for multiple sequential detections without permanent displacement
Solution Approach 2:
The magnetic field generator temporarily discards (releases) magnetic particles from their held position after measurement, allowing them to return to the tethered state. This recovery mechanism enables the same particles to be reused for subsequent measurements, improving productivity while maintaining signal strength
3Device complexity
If standard capture reagent is used, then the device complexity is minimized, but the detection limit for low-concentration analytes is insufficient
Solution Approach 1:
The patent changes the concentration parameter of capture reagents by incorporating gradient concentrations within the hydrogel matrix. This parameter change enables enhanced detection sensitivity for low-concentration analytes while maintaining a relatively simple overall device structure, as the gradient is formed during hydrogel fabrication rather than requiring complex reagent delivery systems
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
Enables non-invasive, low-cost, and wearable detection of various analytes by leveraging magnetic particles and optical waveguides, improving signal-to-noise ratio through repeated measurements and standardization of photonic integrated circuits.
Implementation Method 1
an evanescent field is generated at the exterior surface when the input signal is transmitted into the optical waveguide
Implementation Method 2
a magnetic field generator, the magnetic field generator configured to alternate between a first state in which the magnetic field generator generates a field that forces the plurality of magnetic particles to extend outside of the effective range
Implementation Method 3
the capture reagent holds a first quantity of magnetic particles within the effective range when the magnetic field generator is in the second state and an analyte of interest is not present
Data Source
AI summary
A device for optical biosensing using magnetic particles includes an optical waveguide at least a light source at the input of the optical waveguide, an evanescent field generated at the exterior surface with an effective range, a plurality of magnetic particles tethered to the exterior surface, a magnetic field generator, the magnetic field generator configured to alternate between a first state in which the plurality of magnetic particles extend outside of the effective range and a second state in which the plurality of magnetic particles do not extend outside of the effective range, a capture reagent disposed on the exterior surface that holds a first quantity of magnetic particles within the effective range when the magnetic field generator is in the second state and an analyte of interest is present, and a second quantity when not, producing a first output signal and a second output signal respectively.