Digital Microfluidics Control System II

P15610

Agenda Review

o Problem Statemento Customer Requirementso Engineering

Requirementso Risk Assessment

Market Comparison Functional Decomposition Morphological Chart Concept Selection System Architecture Feasibility Analysis Project Plan

Current state - The current control system is not self contained and uses a class AB amplifier which makes the system large and nonmodular.

Desired state - A fully enclosed control system that efficiently operates the DMF chip while providing accurate feedback.

Project Goals - Make key improvements to functionality of control system, and complete all assigned deliverables.

Repeatable, consistent droplet motion. Durable, lightweight, modular design.

Constraints - Use provided DMF chip, control fluid droplets using electrowetting, use DI water as test fluid, ensure compatibility with peripheral hardware and GUI.

Problem Statement

Customer Requirements

Engineering Requirements

Risk Assessment

Market Comparison

Parameters DropBot NeoPREP

Capacitance Precision ~5pF Not Specified

Droplet Speed Range 0-70mm/s Not Specified

Impedance Precision Not Specified Not Specified

Cost $1500 $150,000

Portability Contained Not Portable

Size 1’x1.5’x1’ 5’x5’x5’

Market Comparison DropBot NeoPREP

Sandia Digital Microfluidics Hub

Functional Decomposition

Morphological Chart

Concept Selection

Oscillator and Demultiplexer

Temperature range:

-10C to 60CCost:$1.00 each

Frequency:100 kHz+Size:Diminutive

Concept Selection

Miniature Circuit Breaker

Trip conditions:5A; 240V

Cost:$18.00

Size:Deck of

cards+

Concept Selection

Server Rack

Weight:2.4 lbs

Cost:$60.00

Size:~Toaster

oven

Concept Selection

Mechanical Heat Sink With Fans

Airflow (HS/fan):55/30 ft3 /min

Cost (HS/fan):$45.00/$4.00

Weight (HS/fan):1.4 lbs/<1 lbs

Size (both):Deck of cards

+

System Architecture

Feasibility Analysis - Capacitive Measurements

Capacitive sensor circuit Circuit should be able to

measure 0.01pF change in capacitance

Sampling Frequency = 4MHz

Requires a comparator

Inexpensive (~$3.00)Example Circuit

Feasibility Analysis - Amplifier

- Requirements are based off the amplifier used in the previous project.

- The current design will use two cascaded common emitter BJTs with a crystal oscillator providing a frequency of 100kHz.

Amplifier Requirements

Input AC Voltage ~117 V

Input AC freq. 60 Hz

Peak Output Voltage

170 Vrms

Capacitive Load 10 nF

Cut off frequency 100 kHz

Voltage gain ~48 dB

Input Resistance 20 kΩ

Ambient Temp. 25 C

Feasibility Analysis - CostElectrical Components Cost (USD)

Control Board $20.00

I/O Board $50.00

Arduino Mega $25.99

Crystal Oscillator $1.00

Amplifier $250.00

Mini Circuit Breaker $5.00

Mechanical Components Cost (USD)

Server Rack $200.00

Fan + Heatsink $60.00

- Rough estimate of Total Cost ~ $600

- Assigned budget is $2000

Feasibility Analysis - Weight

Engineering Requirement: <13,600 g

Engineering Analysis to be Completed

Mechanical - Structural- Shock &

Vibration- Heat

Electrical- Component

Tolerances- Noise Analysis - Power Consumption- Speed of

computation

Project Plan

Questions?