Cam-Based Fluid Delivery System for Microfluidic Assays
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Solution Overview
Problem
Existing microfluidic assay systems face challenges with fluid delivery due to user-dependent consistency, bulky and noisy pneumatic systems, and reliability issues related to temperature and atmospheric pressure, which affect the accuracy and precision of fluid delivery.
Innovation Solution
A compact cam-based control system using a single stepper motor to actuate an array of fluid reservoirs through cams with different profiles, ensuring precise and sequential fluid delivery, reducing noise and complexity, and maintaining accuracy across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pneumatic systems are used to drive fluid along the required path, then fluid delivery can be achieved, but the system becomes expensive, complex, noisy, and dependent on ambient air pressure and temperature
Solution Approach 1:
The patent replaces the pneumatic system with a direct mechanical actuation system. A motor drives a cam mechanism that directly actuates pistons to push fluid through microfluidic channels, eliminating the need for pneumatic components, air pressure regulation, and associated control systems. This mechanical substitution reduces complexity, cost, and environmental dependencies while maintaining reliable fluid delivery.
2Device complexity
If a single stepper motor is used to actuate blister packs, then the system becomes more compact, but precise control of multiple fluid releases requires complex cam profiles and sequencing
Solution Approach 1:
The patent segments the cam mechanism into multiple independent cams, each with specifically designed profiles that correspond to different fluid reservoirs. Each cam controls one or more pistons, and the cams are arranged on a common shaft to enable sequential actuation. This segmentation allows a single motor to precisely control multiple fluid releases through carefully designed cam profiles, achieving both compactness and sequencing precision.
Solution Approach 2:
The cam profiles are pre-designed and pre-configured on the cam shaft to establish the precise sequencing and timing of fluid deliveries. The relative positions and geometries of the cams are fixed during manufacturing, so that when the motor rotates the cam shaft, the predetermined sequence of piston actuations occurs automatically. This preliminary configuration eliminates the need for complex real-time control logic while ensuring precise fluid delivery sequencing.
3Adaptability or versatility
If multiple sets of pistons are operated independently using a cam shaft with clutch system, then each piston set can be controlled separately, but the system becomes more complex with direction-dependent cam rotation
Solution Approach 1:
The patent employs a dynamic cam mechanism where the cam shaft can rotate in either direction, and the cam profiles are designed to accommodate bidirectional rotation. The clutch system is simplified or eliminated by designing cams that function correctly regardless of rotation direction, allowing independent control of different piston sets through directional rotation without adding excessive complexity. This dynamic design provides adaptability while maintaining system simplicity.
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 reliable, precise, and scalable fluid delivery, minimizing the risk of out-of-order fluid flow and backflow, while being unaffected by atmospheric changes, thus enhancing the reliability and precision of assays.
Implementation Method 1
A cam-based control system in which a single motor acts on a cam shaft on which are mounted a plurality of cams with different profiles which in turn act on an array of fluid reservoirs so as to burst the blisters in a predetermined sequence
Data Source
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AI summary
There is provided an assay fluid delivery system comprising an array of fluid reservoirs (62), each of which is selectively actuatable to deliver a respective fluid to a fluid channel structure; and a fluid delivery control system (50) comprising a plurality of reciprocally mounted actuators, each associated with a respective reservoir and being movable between a retracted position and an actuating position at which it causes fluid to be delivered from the corresponding reservoir, a plurality of cams (22) with different profiles mounted on a common, rotatable cam shaft (6), each cam being engaged with a respective one of the actuators whereby rotation of the cams causes movement of the corresponding actuators between the retracted and actuating positions, and a motor coupled to the cam shaft for rotating the cam shaft, wherein the cams are shaped relative to one another so as to cause the corresponding actuators to actuate the reservoirs in a predetermined sequence and for predetermined respective times.