Magnetic Biosensor Actuation Protocol for Uniform Signal Detection
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Solution Overview
Problem
Magnetic biosensor devices face challenges in achieving uniform and rapid signal detection, particularly in multi-analyte assays or multi-chamber configurations due to uneven magnetic field distribution, which slows down the overall assay speed.
Innovation Solution
A magnetic biosensor device with an electromagnetic unit producing varying magnetic field strengths and a duty-cycle adjustment to optimize the attraction and diffusion of magnetic beads, using a combination of magnetic field directions and actuation protocols to enhance bead distribution and binding efficiency across the sensor surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pulsed magnetic attraction schedule is used to attract magnetic beads to the sensor surface, then the concentration of magnetic particles near the sensor surface increases and the binding process speeds up, but the signal near the center of the attraction magnet increases more rapidly than the signal near the poletips, causing uneven signal distribution and slowing down the overall assay speed
Solution Approach 1:
The patent applies periodic magnetic field actuation with varying duty cycles to alternately attract and release magnetic beads. By switching between different magnetic field strengths in a periodic manner, the system achieves both rapid binding at the center and uniform distribution at the poletips, resolving the contradiction between binding speed and signal uniformity.
Solution Approach 2:
The patent dynamically adjusts the duty cycle of the magnetic field actuation during the assay process. The duty cycle varies over time to optimize bead distribution at different stages: higher duty cycles initially to speed up binding, then lower duty cycles to ensure uniform signal distribution across all sensor regions including poletips.
2Productivity
If only a few positions or Regions-Of-Interest near the center of the magnet are used to circumvent the uneven signal distribution, then the assay speed is improved, but multi-analyte assays or multi-chamber configurations become limited
Solution Approach 1:
The patent makes the entire sensor surface, including regions near poletips, functional for detection by using magnetic actuation protocols that ensure uniform bead distribution across all areas. This enables multi-analyte assays and multi-chamber configurations to utilize the full sensor surface area, maintaining both high productivity and versatility.
3Speed
If the magnetic field is continuously applied to maintain high concentration of magnetic particles near the sensor surface, then the binding process is accelerated, but magnetic beads cannot diffuse away from the surface for proper binding equilibrium
Solution Approach 1:
The patent uses periodic magnetic field application with defined duty cycles to alternately concentrate and release magnetic beads. During the 'on' phase, beads are attracted to the sensor surface for rapid binding; during the 'off' phase, beads can diffuse away to maintain proper binding equilibrium. This periodic action resolves the contradiction between acceleration and equilibrium.
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 solution improves the uniformity and speed of signal detection, allowing for efficient multi-analyte assays and multi-chamber configurations by optimizing the duty-cycle and magnetic field orientation, thereby increasing the number of specific bindings and reducing aspecific bindings.
Implementation Method 1
Magnetic attraction of the beads, also referred to as actuation, is essential in order to increase the performance, i.e. speed, of the biosensor for point-of-care applications
Implementation Method 2
When the magnetic field is switched off, beads will diffuse towards the surface or away from the surface, depending of their original position
Implementation Method 3
The detection means comprised in the magnetic biosensor device comprises a light source for directing light onto the sensor surface at an angle of total internal reflection and a detector for detecting light reflected from the sensor surface
Data Source
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AI summary
The present invention provides a magnetic biosensor device comprising a sensor cartridge for receiving an assay to be tested, an electromagnetic unit for producing a magnetic field at a sensor surface of the sensor cartridge, and detection means for detecting the presence of magnetic particles close to the sensor surface. The electromagnetic unit is adapted to periodically produce a magnetic field having at least a first and a second magnetic field strength, the ratio of the amount of time of applying the first magnetic field strength to the amount of time of the period of applying the first and the second field strength being varied during the measurement. The invention further provides a method for applying a magnetic field to a sensor surface of a magnetic bio sensor device.