This document outlines the design and development of a low-cost, electricity-free thermopneumatic micropump aimed at low-resource settings for point-of-care diagnostic applications. The pump operates by generating heat through the reaction of magnesium-iron alloy with saline, which pressurizes a membrane to dispense fluid. Detailed sections cover design optimization, material selection, fabrication processes, and testing methods to ensure functionality and reliability in field conditions.

1. Electricity-free Thermopneumatic Single Dose Micropump
for Low-Resource Setting Applications
Jeff Briner
Travis Gehman
Tariq Packer
Dharma Varapula

2. Objective
To develop a low-cost, micropump for low-
resource setting (LRS)

3. Literature Review
A typical MEMS thermopneumatic
micropump by Jeong and Yang (2000)
[1]
A peristaltic PDMS thermopneumatic
micropump by Jeong et al (2005) [2]

4. Literature Review
A thermopneumatic dispensing
micropump by Cooney et al
(2004) [3]
A thermopneumatic micropump
using surface tensions by Jun et
al (2007) [4]

5. Design - Need statement
There is a need for a
1. simple,
2. inexpensive, and
3. electricity-free
fluid actuation device for point-of-care diagnostics
technology for Low-Resource Setting (LRS).

6. Design Overview
● Existing thermopneumatic micropumps have
non-uniform flow and/or use electricity
● Design principle:
● Reaction of MgFe with saline water generates heat
● Perfluorocarbon (PFC) vaporizes stretching the
elastomeric membrane
● The membrane pressurizes the dispensing chamber
resulting in the efflux of fluid

7. Design Details

8. Design Details/Optimization
1. Depending on MgFe particle size, cellulose matrix porosity
heat generation is controlled
2. Volume of dispensing chamber along with amount of PFC
affects the flow rate
3. MgFe+wick can be made replaceable to allow reuse
4. An array of single units can be used for multiple doses on
the same chip

9. Material Selection [3]

10. Material Selection

11. Material Selection

12. Material Selection

13. Parts
- (3x) 40 mm x 62.5 mm x 2 mm PMMA =
$0.42
- Small strip of cellulose/paper = $0.01
- 2g Mg Fe alloy powder = $0.15
- Copper heating plate = $0.02+$0.25
- 25 mm diameter rubber membrane = $0.10
- Perfluorocarbon liquid = $0.10
- Assembling cost $1.00
Final cost $1.84

14. Fabrication
1. Laser ablation and steralization
2. Base assembly
a. Cellulose wick
b. Heating plate
c. Mg Fe alloy
d. Middle layer
3. Final Assembly
a. Perfluorocarbon fill
b. Seal Rubber membrane
c. Top layer

15. Laser Ablation
Base Layer Middle Layer

16. Laser Ablation
- Removal process
using a CO2 laser
- 2 mm thick PMMA
- Red denotes 1.5 mm
depth removal
- Purple denotes 1.55
mm depth removal
- Blue denotes 0.5
depth removal
Top Layer

17. Base Assembly
1. Sterilization of top layer, middle layer and
membrane
2. Apply surfactant to microchannel in bottom
layer
3. Insertion of paper wick around the edge of
the well

18. Base Assembly 2
1. Insert Copper heating plate into indentation
2. Fill space with Mg Fe alloy powder
3. Apply grease to metal for seal with the
second layer
4. Bond the middle layer to the bottom layer
using acetonitrile.

19. Final Assembly
1. Insert Perfluorocarbon into well formed by
the copper
2. Adhere Membrane to formed indentation
3. Bond the top layer to the middle layer using
acetonitrile.

20. In Field Use
1. Insert pumped material into chamber via
insertion hole
2. Seal insertion hole
3. Insert water into capillary

21. Testing
Multi-phase testing
- Design Testing
- MgFe heat generation
(Bomb Calorimeter)
- MgFe heat generation
vs Particle size
- MgFe heat generation
within chip
- Test Expansion Fluids
- Expansion
- Wettability
(Bomb Calorimeter)

22. Testing
Multi-phase testing
- Implementation Testing
- Response Time
- Correct Dosage
- Scaling Restraints
- Post Manufacturing
Testing
- Shelf Life
- Resistance to
environment
- Ambient Temperature
Actuation
Expected Response Curve

23. Interconnection
Interconnection
- Simple inlet reservoir similar
to lab for actuation
- Exit
- Push to connect ports
- Screw on ports
Mitra/Chakraborty

24. References
[1] Jeong, Ok Chan, and Sang Sik Yang. "Fabrication and Test of a Thermopneumatic Micropump with a
Corrugated p+ Diaphragm." Sensors & Actuators: A.Physical 83.1 (2000): 249-55.
[2] Jeong, Ok Chan, Sin Wook Park, and Sang Sik Yang. "Fabrication and Drive Test of a Peristaltic
Thermopnumatic PDMS Micropump." Journal of Mechanical Science and Technology 19.2 (2005): 649-54.
[3] Cooney, Christopher G., and Bruce C. Towe. "A Thermopneumatic Dispensing Micropump." Sensors &
Actuators: A.Physical 116.3 (2004): 519-24.
[4] Jun, Do Han, Woo Young Sim, and Sang Sik Yang. "A Novel Constant Delivery Thermopneumatic
Micropump using Surface Tensions." Sensors & Actuators: A.Physical 139.1 (2007): 210-5.
For more info on MgFe: http://en.wikipedia.org/wiki/Flameless_ration_heater

25. Answers
Questions?