Disposable Cassette for Automated Nucleic Acid Detection
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Solution Overview
Problem
Current nucleic acid tests are unsuitable for field use due to their requirement for elaborate and costly instrumentation, specialized laboratory materials, and multiple user-dependent manipulations, leading to lengthy turn-around-times and economic barriers for small clinics and remote settings.
Innovation Solution
A disposable cassette with a plurality of chambers, vent pockets, and a heat labile material for sealing, allowing for programmable fluid movement and mixing without external instrumentation, and incorporating a flexible circuit with resistive heating elements and temperature sensors for temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If external instrumentation is used to control fluid movement and temperature, then fluid movement and temperature control can be achieved, but device complexity and cost increase
Solution Approach 1:
The device uses self-contained microfluidic channels with integrated reservoirs that automatically control fluid movement through pressure differentials and capillary forces, eliminating the need for external pumps and valves. The handheld device performs all fluid handling operations autonomously once the test strip is inserted.
Solution Approach 2:
The device combines multiple functions (fluid storage, fluid movement, mixing, temperature control, and detection) into a single integrated handheld unit. The microfluidic chip integrates channels, reservoirs, and reaction chambers in one component, while the handheld device houses all control electronics and detection systems together.
2Productivity
If multiple manipulations dependent on user intervention are required, then the test can be performed, but ease of operation decreases and potential for error increases
Solution Approach 1:
The device automatically performs all test steps including sample application, reagent mixing, incubation, and result detection. The user simply inserts the test strip and waits for results, with the device autonomously managing fluid flow, temperature cycling, and signal detection without requiring manual manipulation or interpretation.
Solution Approach 2:
The device maintains continuous operation through automated temperature cycling and fluid flow management. The microfluidic system continuously pumps reagents and samples through reaction chambers, while the heating element continuously cycles temperatures according to the required protocol, eliminating idle time and manual intervention gaps.
3Measurement precision
If elaborate and costly instrumentation is used, then sensitive and specific detection can be achieved, but cost increases and accessibility decreases
Solution Approach 1:
The device uses a disposable microfluidic chip that contains all reagents and structural components needed for the test. This eliminates the need for expensive, complex instrumentation while maintaining detection sensitivity, as the chip is designed for single-use and then discarded, reducing costs for small clinics and remote settings.
Solution Approach 2:
The device replaces complex mechanical instrumentation with a handheld electronic device that uses integrated circuits for temperature control and optical sensors for detection. The microfluidic chip uses passive fluid handling based on pressure differentials and capillary forces rather than mechanical pumps, significantly reducing device complexity and cost.
4Measurement precision
If samples are shipped to centralized laboratories, then comprehensive testing can be performed, but turn-around-time increases
Solution Approach 1:
The device segments the testing process into a portable, self-contained unit that can be operated at the point of care. The microfluidic chip separates sample processing, reagent mixing, and detection into distinct but integrated zones, allowing the entire testing workflow to occur locally without shipping samples to centralized laboratories.
Solution Approach 2:
The handheld device acts as an intermediary between the sample and the detection system, performing all necessary processing steps locally. The device includes integrated reagent reservoirs and mixing chambers that mediate the interaction between sample and detection reagents, eliminating the need for external laboratory infrastructure and enabling immediate results.
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
Enables rapid, sensitive, and specific point-of-use nucleic acid detection and identification, reducing turn-around-times and costs, and allowing for surge capacity and increased throughput during outbreaks or emergencies.
Implementation Method 1
a heat labile material for sealing one or more of the vent pockets
Implementation Method 2
The protrusion preferably comprises a dimple or an asperity and preferably sufficiently prevents molten heat labile material from attaching to a heat stable material disposed adjacent to the heat labile material
Implementation Method 3
a flexible circuit with resistive heating elements and temperature sensors for temperature control
Data Source
AI summary
A disposable cassette for detecting nucleic acids or performing other assays. The cassette can be inserted into a base station during use. The cassette has numerous features to ensure correct operation of the device under gravity, such as vent pockets for enabling the flow of sample fluid from one chamber to the next when the vent pocket is unsealed. The vent pockets have protrusions to help prevent accidental resealing. The cassette also can have a gasket to ensure free air movement between open vent pockets. A flexible circuit with patterned metallic electrical components disposed on a heat stable material can be in direct contact with fluid in the chambers and has resistive heating elements aligned with the vent pockets and the chambers. The detection chamber, which houses a lateral flow detection strip can have a space below the strip that has sufficient capacity to accommodate an entire volume of the sample fluid entering the detection chamber at a height that enables the fluid to flow up the detection strip by capillary action without flooding or otherwise bypassing regions of the detection strip. The space can also contain detection particles. Recesses in in the cassette channels or chambers can have structures such as ridges or grooves to direct fluid flow to enhance rehydration of lyophilized reagents disposed in the recess. Flow diverters in the chambers can reduce the flow velocity of the sample fluid and increase the effective fluid flow path length, enabling more accurate control of fluid flow in the cassette.