Electricity-free Thermopneumatic Single Dose Micropump for Low-Resource Setting Applications

Jeff BrinerTravis Gehman

Tariq PackerDharma Varapula

Objective

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

Literature Review

A typical MEMS thermopneumatic micropump by Jeong and Yang (2000) [1]

A peristaltic PDMS thermopneumatic micropump by Jeong et al (2005) [2]

Literature Review

A thermopneumatic dispensing micropump by Cooney et al (2004) [3]

A thermopneumatic micropump using surface tensions by Jun et

al (2007) [4]

Design - Need statement

There is a need for a1. simple, 2. inexpensive, and3. electricity-free fluid actuation device for point-of-care diagnostics technology for Low-Resource Setting (LRS).

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

Design Details

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 reuse4. An array of single units can be used for multiple doses on

the same chip

Material Selection [3]

Material Selection

Material Selection

Material Selection

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

Fabrication

1. Laser ablation and steralization2. Base assembly

a. Cellulose wickb. Heating platec. Mg Fe alloy d. Middle layer

3. Final Assemblya. Perfluorocarbon fillb. Seal Rubber membranec. Top layer

Laser Ablation

Base Layer Middle Layer

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

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

Base Assembly 2

1. Insert Copper heating plate into indentation2. 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.

Final Assembly

1. Insert Perfluorocarbon into well formed by the copper

2. Adhere Membrane to formed indentation3. Bond the top layer to the middle layer using

acetonitrile.

In Field Use

1. Insert pumped material into chamber via insertion hole

2. Seal insertion hole 3. Insert water into capillary

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)

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

Interconnection

Interconnection- Simple inlet reservoir similar

to lab for actuation

- Exit- Push to connect ports- Screw on ports

Mitra/Chakraborty

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

Answers

Questions?