Diagnostic Card Fluidics and Sensor Array Design
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Solution Overview
Problem
Existing diagnostic test cards for chemical analysis are costly to manufacture due to complex designs and assembly processes, and they suffer from performance limitations such as limited shelf stability of fluid reservoirs and potential for explosive fluid evacuation, as well as inadequate anaerobic sample transfer and thermostating.
Innovation Solution
A diagnostic card design featuring a simpler, cost-effective construction with a hermetically sealed fluid reservoir, a valve system that connects the reservoir to the sensor region without pressurization, and a sensor array with a metal heater element for precise temperature control, along with a flexible connector for reduced heat loss and efficient thermal bootstrapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex design with numerous process steps and precision assembly steps is used in diagnostic devices, then the device functionality and sensor performance are improved, but the manufacturing cost increases significantly
Solution Approach 1:
The diagnostic device is divided into separate functional modules: a sensor array module, a fluidic module with reservoir, and a processor module. Each module can be manufactured independently using standard processes and then assembled, reducing overall manufacturing complexity and cost while maintaining functionality.
Solution Approach 2:
The fluidic reservoir serves multiple functions: storing calibrator fluid, providing reference levels for sensor calibration, and enabling automated sample transfer. This multi-functionality reduces the need for separate components and assembly steps, lowering manufacturing costs while maintaining device reliability.
2Stability of the object's composition
If a sealed fluid reservoir is used in diagnostic devices, then shelf stability of calibrator fluids is improved, but the device complexity increases due to sealing and rupture mechanisms
Solution Approach 1:
The fluid reservoir is pre-filled with calibrator fluid during manufacturing and hermetically sealed. The seal is designed to remain intact during storage and transport, providing long-term shelf stability. The seal is intentionally designed to rupture under controlled conditions during use, releasing the fluid for sensor calibration without requiring complex active sealing mechanisms.
Solution Approach 2:
A flexible foil seal is used to close the fluid reservoir. This thin film provides effective hermetic sealing for long-term stability during storage. The flexible nature of the foil allows it to be easily ruptured by a piercing element during use, providing a simple and reliable mechanism for fluid release without complex sealing systems.
3Device complexity
If manual fluid propulsion is used in diagnostic devices, then device complexity is reduced, but the precision and reliability of fluid delivery to sensors is compromised
Solution Approach 1:
The system uses gravity-driven fluid flow where the reservoir is positioned higher than the sensor array. Fluid automatically flows from the reservoir through capillary channels to the sensors when the seal ruptures, eliminating the need for active propulsion mechanisms. This passive gravity-driven system provides reliable and precise fluid delivery while maintaining simplicity.
Solution Approach 2:
The fluid delivery system utilizes capillary action and gravity-driven flow rather than active pumping. The fluidic channels are designed with appropriate dimensions and materials to enable controlled flow through capillary forces, providing precise fluid delivery to the sensor array without requiring complex mechanical or electronic propulsion systems.
4Productivity
If pressurization is applied to the fluid reservoir during fabrication, then fluid flow to sensors is enabled, but the potential for explosive fluid evacuation and segmented flow increases
Solution Approach 1:
The reservoir is filled with fluid during fabrication under controlled atmospheric pressure, not pressurization. The hermetic seal is then applied, and the reservoir is stored in an upright position. Fluid flow to the sensors is enabled by gravity and capillary action rather than pressurization, eliminating the risk of explosive evacuation while maintaining reliable fluid delivery.
Solution Approach 2:
The system changes the pressure parameter from pressurized to atmospheric pressure during fluid filling. The reservoir is designed to be filled at atmospheric pressure and sealed, then operates under gravity-driven flow. This parameter change eliminates the harmful effects of pressurization while maintaining adequate fluid flow through proper channel design and gravity assistance.
5Device complexity
If anaerobic sample transfer is not used in diagnostic devices, then device complexity is reduced, but measurement accuracy for dissolved gases like oxygen and carbon dioxide deteriorates
Solution Approach 1:
The fluid reservoir and fluidic channels are designed to be filled and sealed under anaerobic conditions or with inert gas atmosphere. This prevents oxidation and contamination of the sample fluid during storage and transport. The anaerobic environment is maintained from the point of sample collection through the measurement process, ensuring accurate detection of dissolved gases without interference from atmospheric oxygen or carbon dioxide.
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 enables cost-effective manufacturing, improved shelf stability of calibrator fluids, reliable fluid delivery, and precise temperature control, minimizing heat transport and ensuring accurate measurements, particularly for analytes like oxygen and carbon dioxide.
Implementation Method 1
a hermetically sealed fluid reservoir
Implementation Method 2
a sensor array with a metal heater element for precise temperature control
Implementation Method 3
a flexible connector for reduced heat loss and efficient thermal bootstrapping
Implementation Method 4
a valve system that connects the reservoir to the sensor region without pressurization
Data Source
AI summary
The present invention relates to diagnostic devices incorporating electrode modules and fluidics for performing chemical analyses. The invented devices consist of a sensor array formed on an electrode module, the sensor array being contained within a fluidic housing. The electrode module is a laminate of a perforated epoxy foil and a photo-formed metal foil with sensor membranes deposited into the perforations. The fluidic housing is an element consisting of a plastic card-like body with fluidic conduits and a sealed fluid reservoir contained in a foil-lined cavity.