Design ReviewP15611: Digital Microfluidics Packaging

● Background: 2 - 4● System Analysis: 5 - 7● Concept Development: 8 - 12 ● System Level Proposal: 13 - 18● Engineering Analysis: 18 - 24● Action Items: 25 - 29

Presentation Summary - 1

Problem Statement - 2The goal is to create an enclosure that can deliver fluid and provide a controlled environment for the DMF device.

● Must allow easy camera and microscope access. ● The enclosure must allow for electrical connections to the chip.● Should allow for environmental control and monitoring to maintain

droplet size.● Must adhere to electrical safety and cleanliness standards.● Should allow for easy access to chip between tests.

Current Device - RIT - 3● Eventual goal: ELISA Assay● Will be used in the DMF Lab

○ Resistance Model between Plates

● 120 Channels● Lacks Environmental Controls● Open Chip Enclosure

Current Device - DropBot - 4 ● University of Toronto’s

Wheeler Lab● 320 Channels● Microdrop Graphical User

Interface● Large Enclosure● Measures Position, Velocity,

and Driving Forcehttp://microfluidics.utoronto.ca/dropbot/

Customer Requirements - 5

Engineering Requirements - 6

House of Quality - 7Top 4: Environmental Control, Budget, Maximum Size, Test Setup Time

Size & Setup Time were more important than we expected.

Functional Decomposition -8

Morphological Chart - 9

Morphological Chart - 10

Selection Criteria-11● Cost● Completion Time● Set-Up Time● Ease of Chip Access● Size● Weight

● Environmental Stability● Material Quality (Viewing)● Budgetary Efficiency● Ease of Use● Power● Precision/Accuracy

Concepts - 12

Concept I: Minimal Design Concept III: Alternate DesignConcept II: Dream Machine Concept IV: Selected Design

Pugh Charts - 13

● Concepts III & IV are both are similar in scope● Concept I offers few features and does not make most

efficient use of budget

Concept Sketch - 14

Concept Sketch - 15

Systems Architecture - 16

Systems Architecture - 17

Feasibility - Humidity/Temperature - 18

● Relationship between humidity and temperature

● Warm air holds more moisture than cool air● Approximate relationship:

○ 20 degree F increase decreases humidity by 1/2

Temperature 40 degree F 60 degree F 80 degree F

Relative Humidity 100% 50% 25%

Feasibility - Humidity/Temperature - 19

● Relative Humidity = Partial Pressure/Equilibrium Vapor Pressure

● We are attempting to put the system to its equilibrium point

● Vapor Pressure of water only interacts with water (Dalton’s Law)

● Lowering temperature lowers equilibrium vapor pressure of all reagents

http://crescentok.com/staff/jaskew/isr/chemistry/class16.htm

Feasibility - Temperature Monitoring- 20

● Thermocouple costs range from a few dollars all the way up to 30 dollars per couple.

● More expensive couples are electrically insulated.

● The thermocouples leads can be as small as .0005 inches.

● Standard couple calibrations allow for versatility.

http://www.omega.com/pptst/HSTC.html

Feasibility - Humidity Monitoring - 21

● Digital measurement of the Humidity can done using either capacitive or resistive sensors.

● The cost for the individual sensors range from a few dollars up to 100 dollars.

● The actual size of a capacitive sensor is a 3x3 millimeter squared.

http://www.silabs.com/products/sensors/humidity-sensors/Pages/default.aspx

Feasibility - Viewing access - 22

http://www.zeiss.com/microscopy/en_us/home.html

Feasibility - Fluid Delivery - 23Sandia National Laboratories:● Microfluidics hub with capillary tubes as

fluid delivery medium.● An applied pressure source is used to form a

droplet on the surface of the chip.● DMF actuation separates the droplet from

the capillary tubing.

Kim, Hanyoup, Michael S. Bartsch, Ronald F. Renzi, Jim He, Jim Van De Vreugde, Mark R. Claudnic, and Kamlesh D. Patel. "AUTOMATED SAMPLE PREPARATION PLATFORM FOR NEXT GENERATION DNA SEQUENCING USING A DIGITAL MICROFLUIDIC HUB." (n.d.): n. pag. Sandia National Laboratories, United States of America. Web. <http://www.rsc.org/images/LOC/2011/PDFs/Papers/253_1121.pdf>

Feasibility Peer Review - 24● Look into pressure controls● Consider material for enclosure

○ Preference towards plastic for insulation and electrical safety

○ Glass to prevent autofluorescence effects when using a microscope

Engineering Analysis Needed - 25

● Virtual Model Analysis○ Determine Compartment Volume○ Position capillary tubing, sensors, etc○ Ensure correct sizing of system components

● Calculate temperature requirement for desired relative humidity.

● Calculate pressure required to dispense the desired volume of fluid.

● Test Capillary Function○ Verify fluid delivery

● Test Humidity and Temperature Sensors○ Verify sensor accuracy

● Test Microscope Compatibility○ Verify fluorescence compatibility○ Verify microscope can focus

Test Plan - 26

Project Plan-Subsystems Design - 27

Projected Budget - 28

Risk Assessment - 29

Questions?

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