Diamond Microfluidic Cell for Portable Spin Resonance
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Solution Overview
Problem
Standard NMR devices are unsuitable for integration into microfluidic cells due to their large size and low sensitivity, which limits their ability to resolve precise chemical shift information without strong magnetic fields, making them impractical for portable analytical devices.
Innovation Solution
A microfluidic cell with a diamond sensor containing quantum spin defects, such as NV- defects, is used to detect spin resonance signals, allowing for sensitive chemical shift analysis at lower magnetic field strengths, facilitating miniaturization without compromising functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard NMR devices use inductive rf pickup coils to generate oscillating magnetic field and sense changes, then signal detection is achieved, but device size becomes very large and sensitivity is insufficient for small sample volumes
Solution Approach 1:
The patent replaces the traditional inductive rf pickup coil system with a magnetoresistive sensor system. The magnetoresistive sensor uses a thin strip of ferrous material where resistance changes in response to magnetic field changes, substituting the electromagnetic induction mechanism with a resistive sensing mechanism that enables miniaturization while maintaining detection capability
Solution Approach 2:
The patent changes the sensing mechanism from inductive to magnetoresistive, fundamentally altering how magnetic field changes are detected. This parameter change allows the sensor to be much smaller while achieving comparable or improved sensitivity for detecting NMR signals from microfluidic sample volumes
2Measurement precision
If SQUIDs are used as NMR signal sensors, then signal detection capability is improved, but cryogenic cooling requirements make the device unsuitable for portable applications
Solution Approach 1:
The patent employs magnetoresistive sensors that operate at ambient conditions without requiring cryogenic cooling infrastructure. These sensors can be manufactured using standard semiconductor fabrication techniques, making them inexpensive and suitable for disposable or portable applications, unlike expensive and complex SQUID systems
Solution Approach 2:
The patent extracts the cooling system requirement entirely from the NMR detection system by using magnetoresistive sensors that operate at room temperature. This removes the bulky cryogenic infrastructure while retaining the core signal detection function
3Measurement precision
If alkali-vapour atomic magnetometers are used as NMR signal sensors, then signal detection is achieved, but the requirement for heated vapour cells makes the device unsuitable for portable analytical devices
Solution Approach 1:
The patent uses magnetoresistive sensors that require no heating, no vapour cells, and no complex maintenance. These sensors can be fabricated as simple integrated circuits and used in portable, disposable configurations, eliminating the thermal management complexity of alkali-vapour systems
4Volume of moving object
If magnetoresistive sensors are used in microfluidic cells, then device miniaturization is achieved, but sensitivity is insufficient to resolve precise chemical shift information without strong magnetic fields
Solution Approach 1:
The patent merges the magnetoresistive sensor directly with the microfluidic channel structure, placing the sensor in intimate proximity to the sample. This integration maximizes the magnetic field coupling between the sample and sensor, improving sensitivity to chemical shift information while maintaining miniaturization
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 diamond-based microfluidic cell enables sensitive detection of chemical shifts and magnetic fields, enabling the construction of a small, portable spin resonance device capable of detailed chemical analysis with reduced magnetic field requirements.
Implementation Method 1
A magnetoresistive sensor comprises a thin strip of ferrous material in which a change in resistance occurs when a magnetic field is applied perpendicular to the direction of current flow. The change in resistance is measured and is indicative of changes in the localized magnetic field.
Implementation Method 2
NMR devices function on the principle that certain nuclei possess a quantum spin which generates a magnetic field. By applying a static magnetic field to a sample the spins of these nuclei are preferentially aligned with the applied magnetic field. An oscillating radiofrequency magnetic field is then applied to the sample and the frequency varied. When the oscillating magnetic field comes into resonance with a nuclear spin it flips the nuclear spin to be oriented against the direction of the static magnetic field.
Implementation Method 3
a sensor comprising a diamond material, wherein the diamond material forms at least a portion of a wall defining the microfluidic channel; a plurality of quantum spin defects within the diamond material, uniformly spaced from the channel along its length, and suitable for sensing spin resonance signals from a fluid sample
Data Source
Figure 1(a)~2(b)
Figure 3~4
Figure 5
AI summary
A microfluidic cell comprising: a microfluidic channel (32) for receiving a fluid sample; and a sensor (30) located adjacent the microfluidic channel; wherein the sensor comprises a diamond material comprising one or more quantum spin defects (34). In use, a fluid sample is loaded into the microfluidic cell and the fluid is analysed via magnetic resonance using the quantum spin defects.