Microfluidic Systems in

Environmental Monitoring

Stephan Warnat, PhD Mechanical and Industrial Engineering,

Montana State University 20. October 2017

Water Monitoring Water quality described by: • Physical • Chemical • Biological characteristics of water. Measurements of water quality indicate health of ecosystem.

Remote sampling2,3 1 http://www.shorelinewa.gov/government/departments/public-works/surface-water-utility/water-quality-monitoring 2 www.in-situ.com 3 www.upstatefreshwater.org

Manual sampling1

Expensive Low spatial and temporal resolution

Determining Water Quality Parameters

Physical

• Temperature

• Pressure

• Flow

Biological

• Cell count

• DNA/RNA

• Fluorescence

Chemical

• pH

• pCO2

• Conductivity

Harmful Algae Bloom

T. Sellers Dramatic Algal Blooms in Lake of the Woods Call for Dramatic Action. 01.12.2015 http://tpwd.texas.gov/landwater/water/environconcerns/hab/ga/killphotos.phtml

Some Toxins are dangerous for animals and humans

How to measure changes?

Cell vs. system size

Plant, animal & human cells

Bakteria

MEMS, Microdluidic

Virus

Protine

DNA

Atoms

Transistor size

Structural sizes of

modern transistors

Mic

ro-E

lectr

onic

s

& M

EM

S

NE

MS

What is MEMS?

MEMS is an engineering discipline that studies the design and fabrication of micrometer to centimeter scale systems.

MEMS allow us to create artifical systems that are on the same scale and functionality as insects.

M icro E lectro M echanical S ystem

Scandia Lab

MEMS Example

Accelerometers, gyroscopes (airbag, Wii, EPS, …)

Flow sensors (Mass flow controller,

breath control, …)

Microoptics (Navigation Systems,

optical communication, …)

Microphones in cell phones Needles (Atomic force microsscope,

Medical applications,…)

And more!

Reference on request.

MEMS advantages

On-Chip (phosphate) in microfluidic package1.

Numerous benefits: - Reducing the sensor cost (batch fabrication) - Precise control of dimensions - higher processing speed, high accuracy - High abundance (multiple sensors of same and different kind on small foot

print) - reproducibility, - making the entire sensing system portable

1 Am Jang et al 2011 Meas. Sci. Technol. 22 032001

Challenges

Box

Sensor Sensor

Concept Challenges • Sensors

• Stiffness • Chemical

• Actuators • Media mixing • DEP

• Peripheries • Filter • Pumps

Science Translational Medicine 6 May 2015 Vol 7 Issue 286

Actuator: Media mixing RP Mixing nozzle

Herringbone mixer

Mixing of two fluorescent media

Biological: Cellular Stiffness

10 µm

Biogeochemistry1 Harmful Algal Blooms2 Stiffness change during chemical treatment

10 µm

Allow to study dynamics of cell state.

1 Wilken S. et al, Limnol. Oceanogr., 56(4), 2011, 1399-1410 2 B. Tesson, B. Charrier. Frontiers in Plant Science, V5, Article 471, 2014

Sensor: cell stiffness

Substrate

Frame (d ~ 0,7-0,9 dCell)

Glass

Cell

Stiffness ∝ ∆𝑡, 𝑑𝐹𝑟𝑎𝑚𝑒, 𝑑𝐶𝑒𝑙𝑙 0, Media

Hydrodynamic measurements

Easy to integrate in fluidic system

Micro-Squeezer

Si fabrication with permanent cover (bond)

Material and design development on the micro scale.

MSU Microfabrication Centre

Yeast : Cell differentiation

Compressed State

Non-Compressed State

Viable vs non-viable

S. Warnat, H. King, C. Forbrigger, T. Hubbard. JMM. 25,2,1420-25. JMM Highlight 2015

Reliability

System in seawater: • Corrosion of adhesion promotor • Electrical short between electrodes

Device not functional

Si Atomic Layer Deposition

TiO2 , Al2O3 – lamination stack

5min 80 µm

Not coated

S. Warnat, C. Forbrigger, T. Hubbard, T. Bertuch, G. Sundaram. JVAC A, 33 01A126, 2015

Summary

• Water sampling is important • High spatial and temporal density of multi parameter

field • MEMS allows ‘low-cost’ development

– … and more advantages

• Integration is challenging • Examples:

– Stiffness – Rupture Force – Reliability – (electrochemical sensor)

Acknowledgements

• Mechanical Engineering Dr. T. Hubbard, Dr. M. Kujath, Dr. D. Groulx

R. Schwartz, H. King, C. Forbrigger, B. Barazani

• Process Engineering and Food Science Dr. A. Macintosh, Dr. A. Donaldson

• Medicine Dr. A. Fine

S. Boyd

• Oceanography Dr. D. Wallace, Dr. H. MacIntyre

• Physics Dr. L. Kreplak, Dr. I. Hill