1. Paper Microfluidic Devices
Design Automation for Paper Microfluidics with Passive Flow Substrates
Joshua Potter, William H. Grover, and Philip Brisk
GLSVLSI 2017

2. Outline Introduction & Motivation The Design Framework
Experimental Efforts
Future Work

3. Introduction & Motivation
Design Automation for Paper Microfluidics with Passive Flow Substrates

4. Introduction
The most familiar application of paper microfludics is the home pregnancy test
Additional tests exist for urinalysis (e.g. diabetes)
Low cost
Materials and labor mostly
Reduces the need for sophisticated testing equipment
Point of care
Promises to allow for low-cost, in the field diagnostics and treatments

5. Motivation
The promise of a greater array of diagnostics and treatments
By reducing the amount of man hours needed to develop and test designs
Adaptive Diagnostics
Potential for greater efficacy, efficiency, and accuracy of diagnostics and treatments
Additional design constraints
Fluid dynamics involving capillary action, backflow pressure, volume and flow limitations need to be accounted for in design and fabrication
Environmental factors such as temperature, humidity, barometric pressure may also affect devices

6. Motivation Increasing complexity
a) Symbolized trigger valve b) Time-sequential photographs showing that the gated fluid (blue) was released by the triggering fluid 1
Three fluid lateral flow test based on four fluidic valves 2
1) Chen, Hong, et al. "A fluidic diode, valves, and a sequential-loading circuit fabricated on layered paper." Lab on a Chip (2012):
2) Gerbers, Roman, et al. "A new paper-based platform technology for point-of-care diagnostics." Lab on a Chip (2014):

7. Motivation Hand-designed and fabricated
Requires significant work to produce modifications and iterations
Need for a dynamically generated, parameterized approach
Programmable micropad for urinanalysis 3
3) A. W. Martinez, S. T. Phillips, Z. Nie, C.-M. Cheng, E. Carrilho, B. J. Wiley, and G. M. Whitesides. Programmable diagnostic devices made from paper and tape. Lab-on-a-Chip, 10(19):2499{2504, 2010.

8. fMUX
A version of the multiplexer presented by Martinez, et al.3 built in our framework
Parameterized to allow the end user to specify the number of channels to be selected from
The framework generates the necessary layers and channel placements from a minimum of 2 channels to a maximum based on the size of the substrate(s)
2, 4, 6 and 8 channel fluidic multiplexers (fMUX)
3) A. W. Martinez, S. T. Phillips, Z. Nie, C.-M. Cheng, E. Carrilho, B. J. Wiley, and G. M. Whitesides. Programmable diagnostic devices made from paper and tape. Lab-on-a-Chip, 10(19):2499{2504, 2010.

9. The Microfluidic Framework
Design Automation for Paper Microfluidics with Passive Flow Substrates

10. Framework Overview Stand-alone application developed in C++
Analogous in many ways to chip fabrication
Design process accounts for various conditions and constraints
Fluids and Substrates are characterized within the framework
Desired device(s) with parameters are specified and then the framework generates a layout (if viable) and output to standard printing formats or JSON netlists

12. Design Automation for Paper Microfluidics with Passive Flow Substrates
Experimentation
Design Automation for Paper Microfluidics with Passive Flow Substrates

13. Experimental Setup Wax-based printer Cellulose-based paper substrates
Hydrophobic wax inks allow for printing fluid barriers
Reheated wax penetrates paper to create barriers for the entire thickness of the paper
Cellulose-based paper substrates
Initial tests utilize known paper substrates for consistency

14. Initial Demonstration Tests
A rough, simple pattern printed on a substrate saturated with water dyed with food colorant
Edges folded under to suspend substrate above lab surface
Otherwise, when fluid saturates substrate, fluid will flow across lab surface
Surface not level or even causing erratic fluid travel

15. Raceway Calibration Device
Designed to test various channel widths
Examine volume to distance travel
Variable measurement ticks for in situ measurement of fluid travel

16. Border Containment Tests
Initial experiment using the Raceway Calibration Device
Channels specified with 2.0mm borders
Fluid containment failure due to uneven substrate surface and non-level conditions
Demonstrated need for testing rig

17. Test Rig
Developed and constructed by the authors to provide level surface to substrate under test
Substrate tautly suspended on two sides
Keeps fluid and substrate from contacting lab surface

18. Bullseye Calibration Device
Designed to test fluid travel at various orientations
Can test sink-to-source or source-to-sink
Variable channel lengths and widths, each independently specified
Radial measurement ticks from source to sinks

19. Border Containment Test using Bullseye Device
0.5 mm
1.0 mm
1.5 mm, some leakage
upper right
2.0 mm

20. Design Automation for Paper Microfluidics with Passive Flow Substrates
Future Work
Design Automation for Paper Microfluidics with Passive Flow Substrates

21. Future Work
Capture of environmental conditions within the framework to allow for accurate simulation within the framework prior to fabrication to validate generated devices
Create profiles of various fluids and substrates to determine both successful placement of components and viability of routing solutions of layouts

22. Future Work
Integrating design automation algorithms such as placement and routing of paper microfluidic components within the physical constraints of passive flow and flow-resistant substrates
Explore the applicability of printable circuits for control of fluids over hydrophobic surfaces

23. Design Automation for Paper Microfluidics with Passive Flow Substrates
Conclusion
Design Automation for Paper Microfluidics with Passive Flow Substrates

24. In Conclusion Paper-based microfluidics:
provide portable laboratory tests without expensive actuation equipment
reduce the cost of fabricating new devices and performing diagnostic tests
The authors’ software framework:
can simplify and automate the design process
helps device designers more rapidly prototype new designs and applications through automation
Reduces the time and materials needed to develop and iterate devices

25. Acknowledgements National Science Foundation
This work was supported in part by NSF Award #

26. Thank you!