Miniature Paramagnetic Oxygen Sensor Using Hall Voltage Detection
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Solution Overview
Problem
Conventional oxygen sensors are large, expensive, and require skilled operators, limiting their deployment in smaller scale applications, while existing miniature sensors lack the accuracy and reliability for widespread use in consumer products and medical applications.
Innovation Solution
A miniature gas sensor leveraging the paramagnetic properties of oxygen to measure Hall voltage induced by gas molecule segregation in a magnetic field, utilizing a micro-channel in a semiconductor substrate with an integrated or external magnet, and a differential sensor configuration for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional oxygen sensors are used, then measurement accuracy is achieved, but device size becomes large and cost increases
Solution Approach 1:
The sensor is divided into micro-scale components including a micro-channel cavity, integrated Hall effect sensor, and thin-film magnet, allowing the functional elements to be segmented and integrated on a single chip while maintaining measurement accuracy
Solution Approach 2:
The Hall effect sensor and magnet are integrated within the micro-channel cavity structure, creating a nested configuration where the sensing elements are contained within the micro-scale gas chamber, achieving high precision in a compact form factor
2Reliability
If conventional oxygen sensors are used, then reliable oxygen detection is achieved, but device complexity and operational difficulty increase
Solution Approach 1:
The magnet, Hall effect sensor, and micro-channel cavity are merged into a single integrated device structure, eliminating the need for separate components and reducing system complexity while maintaining reliable oxygen detection
Solution Approach 2:
The sensor utilizes the inherent paramagnetic properties of oxygen molecules directly, requiring no external reagents, catalysts, or complex processing steps, thereby simplifying operation while ensuring reliable measurement
3Volume of moving object
If miniature sensor scale is reduced, then device size decreases, but measurement accuracy and reliability deteriorate
Solution Approach 1:
The sensor exploits the paramagnetic susceptibility parameter of oxygen molecules, which remains constant regardless of scale, allowing accurate measurement to be maintained at micro-scale dimensions through proper utilization of this intrinsic molecular property
Solution Approach 2:
The mechanical or chemical sensing mechanisms of conventional sensors are replaced with a magnetic field-based Hall effect detection system, which operates effectively at micro-scale dimensions without sacrificing measurement precision
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 miniature sensor provides fast response times, low power consumption, and indefinite lifetime, enabling accurate oxygen concentration measurement, suitable for integration in consumer devices and medical applications, with potential for detecting other paramagnetic gases.
Implementation Method 1
A miniature gas sensor leverages paramagnetic properties of oxygen gas to measure a Hall voltage induced by gas molecule segregation in an applied magnetic field
Implementation Method 2
Certain atoms, including oxygen, have a net magnetic dipole moment that tends to align in an external magnetic field
Data Source
AI summary
A miniature oxygen sensor makes use of paramagnetic properties of oxygen gas to provide a fast response time, low power consumption, improved accuracy and sensitivity, and superior durability. The miniature oxygen sensor disclosed maintains a sample of ambient air within a micro-channel formed in a semiconductor substrate. O2 molecules segregate in response to an applied magnetic field, thereby establishing a measureable Hall voltage. Oxygen present in the sample of ambient air can be deduced from a change in Hall voltage with variation in the applied magnetic field. The magnetic field can be applied either by an external magnet or by a thin film magnet integrated into a gas sensing cavity within the micro-channel. A differential sensor further includes a reference element containing an unmagnetized control sample. The miniature oxygen sensor is suitable for use as a real-time air quality monitor in consumer products such as smart phones.