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
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?
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