Thin Film Particle Sensor with 3D Electrode Array
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Solution Overview
Problem
Current particle sensors for conductive fluids are costly, lack accurate sample volume selection, and fail to verify sample presence and flow rate effectively, limiting their sensitivity and practicality for low-cost, disposable applications.
Innovation Solution
A microfluidic sensor with stacked planar thin film layers and electrodes arranged in a 3-dimensional array, allowing single-file particle travel through a particle interrogation zone, with flow termination and detection structures to manage sample volume and flow rate, enabling nonvisual verification and estimation of sample presence and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional particle sensors are used, then particle detection capability is achieved, but cost is high and sample volume control is inaccurate
Solution Approach 1:
The sensor is divided into multiple functional zones including a sample introduction zone, particle interrogation zone, and waste collection zone. This segmentation allows for simplified manufacturing of each zone while maintaining overall detection accuracy, enabling low-cost disposable sensor production.
Solution Approach 2:
The patent introduces a vertical dimension to sample volume control through stacked planar thin film layers with electrodes arranged in a 3-dimensional array. This multi-layer structure enables accurate sample volume selection and flow rate estimation without increasing lateral complexity, resolving the contradiction between detection precision and manufacturing cost.
2Reliability
If conventional sensors without flow control are used, then simple operation is maintained, but sample presence verification and flow rate estimation are not possible
Solution Approach 1:
The sensor structure performs multiple functions simultaneously: particle detection, sample presence verification, and flow rate estimation. The same electrode array and fluid path structure enable all three functions without requiring separate dedicated components, thus improving reliability without proportionally increasing device complexity.
Solution Approach 2:
The sensor uses its own structural features (electrode arrangement, fluid path geometry) to automatically verify sample presence and estimate flow rate without requiring external verification systems. The sensor structure itself provides the means for quality control, reducing overall system complexity.
3Measurement precision
If particles are not constrained to single-file travel, then fluid flow is unrestricted, but particle detection accuracy decreases
Solution Approach 1:
The fluid path has different geometric properties in different zones: a wider sample introduction zone for unrestricted flow, and a narrow interrogation zone for single-file particle travel. This local variation in geometry allows high fluid flow rates overall while ensuring accurate particle detection in the measurement zone.
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 provides a low-cost, disposable sensor capable of accurate particle detection and flow rate estimation, suitable for applications like blood cell counting and whole milk analysis, offering rapid point-of-care testing and potential for reuse.
Implementation Method 1
Pioneering work in particle detection by measuring impedance deviation caused by particles flowing through a small aperture between two containers of electrically conductive fluid is disclosed in U.S. Pat. No. 2,656,508 to W. H, Coulter. Coulter's name is now associated with the principle of particles causing a change in electric impedance as they occlude a portion of the aperture.
Implementation Method 2
measuring impedance deviation caused by particles flowing through a small aperture between two containers of electrically conductive fluid
Data Source
AI summary
A Coulter-style, microfluidic sensor formed by stacking a plurality of substantially non-electrically conductive layers, typically formed from thin polymer films. Certain layers carry patterned electrodes that are arranged to permit their connection to an electrical interrogation circuit. Electrodes may be disposed in a 3-dimensional array in the sensor. A fluid path through the sensor includes an orifice sized to promote single-file travel of particles. The orifice may be defined by the entrance to a hole passing through at least one layer and at least one electrode. Particles entrained in an electrolytic carrier fluid may be detected, or otherwise characterized, by interrogation circuitry connected to the sensor. Certain sensors may include portions of a fluid path disposed parallel to the layers. In certain preferred embodiments, the sensor is carried by a cartridge, which is adapted to couple with an interrogation platform. Desirably, such coupling places the sensor in-circuit with operable interrogation electronics, as well as with a fluid-flow control device. Structure included in a cartridge may provide fluid sample loading, routing, and storage capabilities.