Group R14300 –

Digital Microfluidics

Peter Dunning

Paulina Klimkiewicz

Matthew Partacz

Andrew Greeley

Thomas Wossner

Wunna Kyaw

Problem Statement

• Need for point of care medical testing devices where

access to conventional tests is restricted

o Ex: Doctor’s Offices, Remote Areas, Battlefields

• A solution must be portable and cheap

Problem Statement

• Lab-on-a-chip devices

are capable of

miniaturizing and

automating biological

protocols.

• Devices suited for

commercial use have

just started to be

developed.

http://2.imimg.com/data2/GK/EX/MY-920622/micro-biological-testing-250x250.jpg

http://www.lionixbv.nl/technology/technology-microfluidics.html

Digital Microfluidic Devices -

Electro-wetting

Cross-section view of Digital Microfluidic device. Dotted

line indicates the shape of the meniscus before

actuation. Modified from [2]

“Top view of flow on a ring structure” [3]

● Array of electrodes which use

the electrowetting effect to

manipulate droplets.

Voice of the Customer

Voice of the Customer

Functional Decomposition

Much room for

creativity

Little to no room

for creativity

Medium amt. of

room for creativity

Project Breakdown

• Control System

• Fluid Delivery System

• Fabrication

• Automation

• User Interface

• Packaging

Control System - Specs and Metrics

Problem: Can an Arduino board be used to control a DMF device

to the same or better accuracy as a NI PXI control system?

What Do We Need?• Generate a sine wave

• Amplify the wave to a large voltage (~90-110 Vrms)

• Measure capacitance with a good resolution (~0.2pF)

• Complete the protocol quickly (~30min)

• Move/Merge droplets quickly (~100ms)

• Split droplets quickly (~500ms)

What Do We Know?• Benchmark: Dr. Schertzer completed these protocols at the

University of Toronto using a National Instruments (NI) control

system, a signal generator, and an amplifier

Control System - Potential Concepts

Benchmark - Control System used in Schertzer et al

1. NI PXI System

a. Signal Generator

i. Voltage: 10Vp-p

ii. Frequency: 10kHz

b. Controller

c. Matrix-Switching Device (4

inputs / 32 outputs)

2. Agilent 4288A Capacitance Meter

a. Resolution to ~0.20 pF

3. Custom Amplifier

a. Voltage: 90-110 Vrms

Control System - Potential Concepts

- Generates a sine wave

• Voltage: up to 20 Vp-p

• Frequency: (0.1-50)kHz

Signal Generator BoardControl Board

- Controls is a shield for the

Arduino Microcontroller

Switching Board

Arduino Dropbot System in Fobel et al

Trek Model PZD700A High Voltage

Amplifier

• Input Voltage: 0 to ±10 VDC

• Output Voltage: 0 to ±700 VDC

- Droplet was found to

completely cover an electrode

in 200ms

• Arduino is open source

o firmware

o pin mapping

o board schematics

• KiCAD Hardware designs

available for Board designs

• 320 independent channels and is

highly modular

Control System - Potential Concepts

- Controls Signal Generator Board, High Voltage Switching Board

- Can estimate drop position, velocity

- Software Available:

● Arduino firmware

● C++ Software

● Microdrop Plugin

Arduino Mega 2560 Microcontroller

• Arduino is open source

o firmware

o pin mapping

o board schematics

• KiCAD Hardware designs

available for Board designs

• 320 independent channels and is

highly modular

Arduino Dropbot System in Fobel et al

Control System - Feasibility

● The Arduino Dropbot system used in

Fobel et al paper was able to

instantaneously measure droplet

velocity, capacitance, and impedance

in real time.

● Arduino has:

a. Software: C++ software, Open

source firmware

b. Hardware: Microcontroller with

board schematics, and pin

mapping

● Dropbot has:

a. Software: Open source firmware,

Microdrop Plugin

b. Hardware: KiCAD models to

create the boards

Potential Staffing Needed

● Mechanical Engineering

● Electrical Engineering

● Software Engineering

● Computer Engineering

Fluid Delivery System-HOQ

Fluid Delivery System-Specs and Metrics

Problem:

Is there a specific delivery system so that the desired

volume of fluid can be extracted within the desired

time?

What We Need

• Droplet to be extracted between .5s and 5s.

• Droplet Volume must be within 3% error of desired

volume.

What We Know

• Conventional Biological Protocols have been using

pipettes and Syringes

• Duke University have used Reservoirs in their DMF

Devices.

Fluid Delivery System-Concepts

• Syringe

o .55 L ± .028

• Pipette

o 1µL ± 4%

• Reservoir

o Volume from User Input

• Plug-in Canister

o Desired Volume can be extracted

• Combination of These

Fluid Delivery System- Feasibility

• Solutions

o Reservoir system will allow us to easily dispense

the fluids to the DMF device.

Using together with Pipettes will allow us to

accurately dispense the desired droplet volume.

o Plug-in Canister can be programmed to dispense

the right amount while easily detachable and

portable.

• Staffing Required:o Students in the Mechanical Engineering discipline

o Students in the Industrial Engineering discipline

Fabrication- HOQ

[10]

Fabrication: Potential Concepts

Common

Techniques:Photolithography and

wet or dry etching (clean room)

Solutions outside the clean room:

• PDMS stamp used to transfer a

pattern onto a gold surface

• Desktop laser printer pattern

transfer: directly onto sheet of

polyimide

• Permanent marker electrode array

outline

Dielectric: Saran wrap

Hydrophobic coating: Rain-X

Fabrication: Feasibility

Microcontact printing (microCP) [7]

• PDMS stamp used to deposit patterns of self assembled

monolayers onto a substrate

• device capable of full range of operations: dispensing,

merging, motion and splitting

Formed from circuit board substrates and gold compact

disks using rapid marker masking [8]

● procedure capable of producing devices with 50-60 μm

spacing between actuating electrodes

● saran wrap used a removable dielectric coating

● rain-x: hydrophobic coating

● able to move merge and split 1-12 μL droplets

Desktop Laser Printer Pattern transfer [9]

• Droplet motion: comparable to performance on chips

made by photolithography

• ultrarapid: 80 chips in 10 mins

Automation - HOQ

Automation - Specs and Metrics

Problem: Can a protocol be automated using existing

computing methods and hardware?

What Do We Need?• Data Storage (~0.5GB)

• Send Signal

• Receive Signals

• Processor (>10kHz, ~0.5GB)

• Motion Planning

What Do We Know?

• Many algorithm based computing solutions

already exist, just must be tailored for this

specific application

Automation - Potential Concepts

How to compute:

• Existing computer

• On-board processor

• Open-source system

Function:

• Inputs: state of each electrode, protocol

• Process: compute necessary move, merge, mix &

split instructions for a specified protocol

• Outputs: signals to activate control system

switches, error signal to the user interface, result

Automation - Feasibility

Needed

Features:Available Solutions:

Data Storage Memory Card, HD, SSD,

Peripheral networking, ROM

cartridge

Send Signals Analog signals, digital signals

Receive

Signals

Many ways to process signals..

Processor Micro-processor, multi-core

processor

Motion

Planning

Grid based algorithm, Sampling

based algorithm

Each feature has many well known solutions. This project is determined to be feasible.

User Interface HOQ

User Interface - Potential Concepts

-Computer program w/ visual

display (i.e. LabVIEW VI)

-Touchpad

-Manual input (i.e. turn dials)

-Remote communication (i.e.

email)

-LED indicators

-Combination of these

LabVIEW Front Panel [4]

Example of “lab

on a chip” [5]

Handheld DMF

device [6]

User Interface - Feasibility

Technical Feasibility

-Concepts for the user interface exist in many forms

-Many existing DMF devices are able to accept

instructions and output results via a user interface.

-Example: RIT currently uses LabVIEW interface

provided by National Instruments

Staffing Requirements

A few IE, ME, and EE students, possibly a CE as well

Packaging HOQ

Packaging-Concepts

Minimizing Evaporation

• Humidity sensing/controlo Humidifier/hygrometer/controls

• Temperature sensing/controlo Refrigerator/thermometer/controls

• Hybrid

Packaging-Feasibility

Verify that size and weight constraints are

met:

Staff required: Several ME students, several

EE students, possibly IE students

Questions/Areas of Uncertainty

• How will environmental controls be

implemented?

• Chip form factor?

Next Steps

• Confirm ER’s

• Continue to refine HOQs

• Examine resource and staffing

requirements

• Begin PRP development

• [1] Mark, D., Haeberle, S., Roth, G., Von Stetten, F., and Zengerle, R., 2010, "Microfluidic Lab-on-a-

Chip Platforms: Requirements, Characteristics and Applications," Chemical Society Reviews, 39(3),

pp. 1153-1182.

• [2] Cho, S. K., Moon, H. J., and Kim, C. J., 2003, "Creating, Transporting, Cutting, and Merging Liquid

Droplets by Electrowetting-Based Actuation for Digital Microfluidic Circuits," Journal of

Microelectromechanical Systems, 12(1), pp. 70-80.

• [3] Fair, R., The Electrowetting Effect (in Air), February 1, http://microfluidics.ee.duke.edu/

• [4] http://www.mstarlabs.com/software/labview.html

• [5] http://www.inc.com/magazine/201111/innovation-a-blood-test- on-a-chip.html

• [6] http://doktori.bme.hu/bme_palyazat/2011/tudomanyos_muhely/ szenzorlabor_en.htm

• [7] Watson, Michael W. L., Mohamed Abdelgawad, George Ye, Neal Yonson, Justin Trottier, and Aaron

R. Wheeler. "Microcontact Printing-Based Fabrication of Digital Microfluidic Devices." Analytical

Chemistry 78.22 (2006): 7877-885. Print.

• [8] Abdelgawad, Mohamed, and Aaron R. Wheeler. "Low-cost, Rapid-prototyping of Digital

Microfluidics Devices." Microfluidics and Nanofluidics 4.4 (2008): 349-55. Print.

• [9] Abdelgawad, M., and A. R. Wheeler. "Rapid Prototyping in Copper Substrates for Digital

Microfluidics." Advanced Materials 19.1 (2007): 133-37. Print.

• [10] Schertzer, M. J., R. Ben-Mrad, and Pierre E. Sullivan. "Mechanical Filtration of Particles in

Electrowetting on Dielectric Devices." Journal of Microelectromechanical Systems 20.4 (2011): 1010-

015. Print.

References

End

Questions?