Engineer’s Notebook

Engineering Team Name:________________________

Ingenious! Scheme

Credit: Adam Fenster/University of Rochester

Microfluidics and NanofluidicsDesign of problem-based learning activities in the field of microfluidics for 12-13y old participants“Small Plumbing!”: Empowering the Next Generation of Microfluidic Engineers

Bridle, H.1, Morton, J.2, Cameron P.3, Desmulliez, M.P.Y.4, Kersaudy-Kerhoas, M.1,51Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS2Institute of Photonics and Quantum Systems, Heriot-Watt University, Edinburgh, EH14 4AS3Novo Science Ltd., 3 Hatton mains Cottages, Dalmahoy, Edinburgh, EH27 8EB4Institute of Signal, Sensors & Systems, Heriot-Watt University, Edinburgh, EH14 4AS5Division of Infection and Pathway Medicine, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB Corresponding author: m.kersaudy-kerhoas@hw.ac.uk

Important Timing Criteria

When you hear the whistle blow, your team must move on to the next section with the whistle in the top left corner of the page!

The Project

Aim: To solve a problem using microfluidics that can help scientific research of the wider society. Project Success Criteria: The success of the project will be based on the following three criteria

1. How well does the team work together 2. Can the team design a microfluidic chip to provide a

solution to the given problem 3. Can the team write a scientific report on the testing

of their microfluidic chip Project Skills: The skills that you will require to complete this project are

Teamwork Problem Solving Creativity Written Communication Numeracy

Project Timeline:

Session 1: Class Lecture on Microfluidics Session 2: Design of Microfluidic Chip Session 3: Testing Microfluidic Chip

The Engineering Design Process

Define the Problem

Specify the Requirements

Brainstorm Solutions

Background Research

Build a Prototype Product

Test the Product

Communicate the Results

Your Team

Name(s) of the person(s) helping you Today:

__________________________________________________

__________________________________________________

What do they do?

__________________________________________________

__________________________________________________

Why have they chosen a STEM (Science, Technology, Engineering and Maths) subject?

__________________________________________________

__________________________________________________

Before we start! Let’s meet your team! Discuss with the engineering mentor(s) helping you today. What are their names? Assign a scribe to fill in the questions.

Re-cap: Microfluidic Engineering

In the classroom you learnt about microfluidic engineering. Let’s see how much you remember about these key facts.

Write down 1-2 sentences to answer each of the following questions: What do engineers do? __________________________________________________ __________________________________________________ What are microfluidic chips? __________________________________________________ __________________________________________________ What is the difference between laminar flow and turbulent flow? __________________________________________________ __________________________________________________

http://chemistry.beloit.edu/Edetc/nanolab/shrink/index.html

Re-cap: Reynold’s Number

We can use the Reynolds number to predict if the flow of fluid will be Turbulent or Laminar. We can work out the Reynolds Number using the following equation: Where ρ is the density of the fluid 𝑄 is the volume flow rate of the fluid 𝐷is the hydraulic diameter μ is the dynamic viscosity A is the cross-section area of the tube

Very Large Re (> 2300) = Turbulent Flow Very Small Re (< 2300) = Laminar Flow

𝑅𝑒 =𝜌𝑄D

𝜇𝐴

Reynold’s Number Calculation

Drain Pipe ρ = 1000 Kg/m3

𝑄 = 0.01 m3/s 𝐷 = 0.1 m μ = 0.0009 Kg/ms A = 0.01 m2

Re = ____________ Microfluidic Channel ρ = 1000 Kg/m3

𝑄 = 0.000000001 m3/s 𝐷 = 0.0022 m μ = 0.0009 Kg/ms A = 0.0000001 m2

Re = ____________ Compare your results. Which flow will be Turbulent/Laminar? __________________________________________________

Pipe Diameter = 10 cm

Channel Width = 500 μm

Let’s calculate the Reynold’s number for water flowing through a drain pipe and water flowing through a microfluidic channel.

Roles in the Team

Did you know that there are different types of engineers? Assign each member of your team to an Engineering Role:

Engineer Role and Responsibilities Team Member(s)

Name

Project Engineer (1)

• Time Keeping • Deciding on materials and

equipment to use • Overseeing the design process

Mechanical Engineer (2-3)

• Incorporating the correct processes into the microfluidic chip

• Carrying out the test experiment with the Test Engineers

• Creating solutions to engineering problems

Test Engineer (1-2)

• Deciding how the solution will be tested

• Designing the test experiment • Responsible for the safety of the

testing experiment

Support Engineer (1)

• Transfer of design onto computer software

• Supporting all other engineering roles

Defining the Problem

Ask the Engineering Mentor helping you what the problem is that your team have been asked to solve. Fill in the following: What is the problem or need? __________________________________________________ __________________________________________________ __________________________________________________ Why is it important to solve? __________________________________________________ __________________________________________________ __________________________________________________ How can microfluidics be used to solve the problem? __________________________________________________ __________________________________________________ __________________________________________________

Your team has been asked to use your engineering skills to find a microfluidic solution to a particular problem.

How is a Microfluidic Chip Made?

A microfluidic chip is made up of a stack of carefully designed layers, which are sealed together using a glue.

The top and bottom (substrate) layers provide the roof and floor for the channels in the middle layer. Inlet and Outlet holes are required in the top layer to put the fluid in/let the fluid out.

Substrate Base

200 μm thick layer with microfluidic channels

Top Layer

Fluid Inlet Holes Fluid Outlet Holes

Microfluidic Channels

Example of a complete microfluidic chip

How is a Microfluidic Chip Made?

How are the holes and channels created? The equipment that will be used to manufacture the prototype of your microfluidic chip is called a Laser Cutter. This machine uses a laser beam of very high power to cut through materials including plastic and paper.

Technical Specifications Maximum Cut Depth = 150-1000 μm Minimum Channel Width = 150-500 μm Maximum Sample Area = 10 cm x 10 cm

Brainstorm Microfluidic Solutions

Start by writing down they key design requirements for your chip. The 1st process that the chip must do is to: __________________________________________________ __________________________________________________ __________________________________________________ The 2nd process that the chip must do is to: __________________________________________________ __________________________________________________ __________________________________________________ The 3rd process that the chip must do is to: __________________________________________________ __________________________________________________ __________________________________________________

You are now ready to design a microfluidic chip that will solve your problem.

Which material do you require to make your chip?

Circle the material that is the best to use for your chip.

Plastic

Pros: Cheap, Strong, Easy to Use. Cons: Difficult to Decompose

Paper

Pros: Very Cheap, Easy to Decompose, Renewable Cons: Fragile, Only Use Once

Spie.org

What processes must your chip perform?

Circle all process modules that will be required for your chip.

Inlets and Outlets What they do: Allow fluid in and Out of the microfluidic chip.

In Out

Channels What they do: Connect process modules together.

Delays What they do: Connect process modules together over long path to allow time for a reaction to occur.

What processes must your chip perform?

Mixers What they do: Introduce turbulent mixing to speed up mixing.

Separators or Filters What they do: Separate components of a fluid by diffusion, or application of an external force.

Reactors or Chambers What they do: Provide a chamber in which multiple fluids can interact or react.

Albert Folch, University of Washington

Comsol.com

What processes must your chip perform?

Gradient Generators What they do: Mix fluids together to provide a gradient in mixture composition at the output.

Custom Modules If you require any custom modules specific to your problem, draw them here. Check with your Engineering Mentor if any custom modules are required.

M. Khine, University of California

Designing Your Microfluidic Chip

Now that you know which processes modules you require, use the plastic process modules and large sheets of paper to finalise your microfluidic chip design. Before you start, think of how many different layers you need for you design: Number of layers needed:_____

Designing Your Microfluidic Chip

Once you have finalised your design you are ready to draw it using a computer. Doing so will generate a digital file that will be used by a laser cutter to cut each layer of your design.

The Support Engineer will draw the final design onto the Computer Aided Design (CAD) software, with the help of your Engineer Mentor.

Turn the page to see some examples of what Engineers use their computer software to design…

Designing Your Microfluidic Chip

Did you know that Engineers use computer software to design all of these things?

Top: Stadium Left: Prosthetic Knee Right: Engine

The Project Engineer, Mechanical Engineers and Test Engineers must now design a suitable experiment to test your Microfluidic chip. You must find out and report how well does your chip solve the original problem? Use the space in the next two pages to draw a diagram of the experimental set-up that you will use to test your chip. Then fill in the Risk Assessment. Use the following questions to help you design your experiment: What pieces of equipment will you require? (microscope, fluid pump, beaker, etc.) What chemicals will you require? (water, coloured dyes, polystyrene beads, etc.) Do you require electricity? How long will it take? Do you need to repeat it? How will you know if it worked?

Testing Your Microfluidic Chip

Test Experiment

Test Experiment

Safety – Risk Assessment

It is very important to consider all of the safety risks involved in testing your microfluidic chip. These risks could be due to moving parts, sharp objects, high temperatures, or laser radiation. It is important to write down what precautions will be taken to minimise all of the safety risks involved. Risk 1: __________________________________________ What precautions will be taken to minimise these risks? ________________________________________________ ________________________________________________ ________________________________________________ Risk 2: __________________________________________ What precautions will be taken to minimise these risks? ________________________________________________ ________________________________________________ ________________________________________________

Safety – Risk Assessment

Risk 3: __________________________________________ What precautions will be taken to minimise these risks? ________________________________________________ ________________________________________________ ________________________________________________ Risk 4: __________________________________________ What precautions will be taken to minimise these risks? ________________________________________________ ________________________________________________ ________________________________________________

Build a Prototype

Congratulations! Your design is ready to be built into a prototype microfluidic chip at Heriot-Watt University. You will receive regular updates about how your chip is being made, photos of what it looks like and any problems that have been found along the way.

In the next session, you will be given your microfluidic chip to test! You will need to carefully carry out the test experiment that you designed and record the results. There is more information at the end of your notebook on writing a scientific report. Remember that the team with the best microfluidic chip design and report will win the competition (turn the page to find out more). Good Luck!

Next Session – Testing Your Chip

Competition

The winning team who fills in their Engineering Notebook correctly and produces the best Engineering Report will be announced at the Award Ceremony at the Royal Society in Edinburgh.

This team will have the opportunity to exhibit their winning microfluidic chip at a science fair and tell the public about what their chip does.

Report

Writing a comprehensive scientific report is vital to tell the rest of the world about the engineering solution that you have created. You must present a critical evaluation of your experimental testing results, describing what tests you carried out and what the results were. Below are the key components of an experimental report. Introduction Describe the problem and describe what your solution to the problem is. Say what current solutions are available and explain why your solution is better. Experimental Method Describe the method that you used to test your product. There must be enough detail so that another engineer could repeat your test by reading your report. Results State clearly what the results of your tests were. Bad or unexpected results are just as useful as good results, so make sure to include all relevant information. Conclusions State the main results of your test and compare the performance of your product to other solutions that are currently available. Is your product better or worse?

References

Cover Photo: Ramprasad, VR (2013) [Photograph] At: http://www.tracktec.in/2013/10/Super-thin-membranes-clear-the-way-for-chip-sized-pumps.html (Accessed on 10.11.14) Polymer Microfluidic Photo: Lewotsky, K (2010) [Photograph] At: http://spie.org/x43433.xml (Accessed on 10.11.14) Paper Microfluidic Photo: Polymer Microfluidic Devices, Syntec Optics [Photograph] At: http://syntecoptics.com/polymer-microfluidic-devices/ (Accessed on 10.11.14) Gradient Generator Photo: Chemical & Engineering News (2007) [Photograph] At: https://pubs.acs.org/cen/news/85/i49/8549news2.html (Accessed on 10.11.14) Team Photo: Our Team. Oil Gas Engineering Consultancy (2014) [Photograph] At: http://www.oilgasec.com/ (Accessed on 11.11.14) Reaction Chamber Photo: University of Washington (2014) [Photograph] At: http://www.washington.edu/news/2008/01/10/source-images-microfluids-photo-gallery (Accessed on 17.11.14) Drain Pipe Image: Recycore Technology [Image] At: http://www.recycoretechnology.co.uk/images/drain_pipe_110_160.jpg (Accessed on 11.11.14) Microfluidic Cross Section Image: Resonetics [SEM Image] At: http://www.resonetics.com/pages/markets-invitro.php (Accessed on 11.11.14) Football Stadium: AMENFIS (2014) [Image] At: https://www.amenfis.com/training/autocad/ (Accessed on 17.11.14) Engine: 3D RussianCAD (2014) [Image] At: http://www.3dcadworld.com/russian-cad/ (Accessed on 17.11.14) Prosthetic Knee: Bailey-Parks Urethane (2012) [Image] At: http://www.baileyparks.com/blog/urethane-molding/polyurethane-and-prosthetics-manufacturing/ (Accessed on 17.11.14) Laser Cut Wood: Free Art Friday Atlanta [Photo] At: http://www.fafatl.com/2014/04/16/laser-cutting-vendors-in-atlanta/ (Accessed on 18.11.14) Engineering Design: Marc Automation [Photo] At: http://marcautomation.com/website/Design_Engineering.aspx (Accessed on 18.11.14) AutoCAD workspace: Qweas [Image] At: http://www.qweas.com/downloads/graphic/cad/screenshots-mesh-to-solid-for-autocad.html (Accessed on 18.11.14) Problem Image: Primary Blogger [Image] At: http://wilbo168.primaryblogger.co.uk/problem-solving-maths-games/ (Accessed on 11.11.14) Whistle Image: IconArchive [Image] At: http://www.iconarchive.com/show/soccer-icons-by-artua/whistle-icon.html (Accessed on 11.11.14)

School session 2: 1h30

Group meet with you> Discuss who you are, what you are doing, (bring props)

10min

Re-cap the techniques/building blocks/material 5min

Introduce and choose the different roles 5min

WHISTLE – Move to Next Stage

Discuss the problem 5min

Recap how are chips made 5min

Establish requirements 5min

Choose Process Modules 10min

WHISTLE – Move to Next Stage

Draw/draft system 15min

WHISTLE – Move to Next Stage

Draw system on CAD, Design Test Experiment, Discuss risk assessment

20min

Discuss report + Any Questions 5min