P15611: Microfluidics Packaging
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Systems Design

Table of Contents

Systems Design

When considering the overall aims of this project, it is important to remember the packaging device’s role as support to the experimental Digital Microfluidic Chip (DMF). The most important function of the DMF Packaging is to maintain a controlled environment to ensure stable testing conditions for the small volumes of fluids used in the DMF device. In designing for this, we realize the emergence of secondary systems. Although we are enclosing the device, the team aims to to enable environmental control, and allow access to the chip to deliver fluid and electrical signals. These become subsystem considerations. In addition visual access to the chip remains an important part of running experiments. In system design we aim to determine the ways these functions interact with each other and begin to propose potential solutions.

Functional Decomposition

The team broke down the intended functionality of the DMF Enclosure into five primary functions: Deliver Fluid, View Droplet, Provide Electrical Connection, and View Chip. From the functional decomposition we selected concepts around which we could develop our design. This can be seen below:
Functional Decomposition

Functional Decomposition

Benchmarking

Benchmarking proved some difficulty as there are no devices on the market that perform the same functions as this project aims to achieve. Two devices that we looked at were the Sandia Lab Digital Microfluidics Hub and the University of Toronto’s DropBot. The University of Toronto’s Wheeler Laboratory has published a great deal on their DropBot and their resources have proven very useful during our design process.
Sandia National Laboratories' Microfluidics Hub

Sandia National Laboratories' Microfluidics Hub

Wheeler Microfluidics Laboratory's Dropbot

Wheeler Microfluidics Laboratory's Dropbot

Concept Development

Concept Generation

Morph Table

Morph Table

Morphology Chart

Morphology Chart

Concept Selection

public/Systems Level Design Documents/Selection Criteria.JPG

public/Systems Level Design Documents/Selection Criteria.JPG

public/Systems Level Design Documents/Concepts.JPG

public/Systems Level Design Documents/Concepts.JPG

Initial Concept Sketches

Systems Architecture

The systems architecture breaks down the functionality of the design into multiple subsystems, and illustrates how the components work together.
High Level System Breakdown

High Level System Breakdown

Detailed System Breakdown

Detailed System Breakdown

Feasibility

The feasibility analysis was a preliminary portion of the engineering analysis. It was done in order to validate that the intended design is indeed feasible.

Temperature and Humidity

Temperature vs. Vapor Pressure

Temperature vs. Vapor Pressure

The intended design aims to control the relative humidity in the enclosure by use of temperature controls. Research showed us that there exists a relationship between temperature and relative humidity. Relative Humidity is the ratio of the partial vapor pressure to the equilibrium or saturated vapor pressure. Lowering the temperature of a fixed volume of air will cause the equilibrium vapor pressure to decrease and thus the relative humidity to increase.

Viewing Access

Microscope Clearance

Microscope Clearance

A major constraint for the size of the enclosure is the clearance of the microscope. The team physically measured the clearance of the microscope that will be used with this DMF packaging system.

Fluid Delivery

In order to prove the feasibility of the intended fluid delivery system, which involves capillary tubing and pressure controls, the team decided to benchmark against the Sandia National Laboratories' Microfluidics Hub (see Benchmarking above):

Risk Assessment

Systems Design Review

The Systems Level Design Review has been completed. It can be seen here.


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