1. Nano and Microfluidics Laboratory (NMfL) Suspensions and Colloids Ishan Wathuthanthri iwathuth@stevens.edu Department of Mechanical Engineering Stevens Institute of Technology New Jersey, USA

2. Nano and Microfluidics Laboratory (NMfL) Suspensions Particles larger than ~1000nm. Separated by gravity. Examples (sand/water, dust/air)

3. Nano and Microfluidics Laboratory (NMfL) Making An Interesting Suspension Mix two parts cornstarch to one part water. 100ml cornstarch (large beaker) 50ml water (small beaker) Place cornstarch into a ziploc bag and add water. Close bag and mix. Write down some characteristics of this suspension.

4. Nano and Microfluidics Laboratory (NMfL)

5. Colloids Particles upto ~100nm. Cannot be separated by gravity

6. Nano and Microfluidics Laboratory (NMfL) Example of a Colloid- Ferrofluids Ferrofluids- “ferro” iron. Polarized in a magnetic field. Colloidal mixture of iron particles suspended in a carrier fluid. Generally particles ~10nm. Reference- L.Mao and H. Koser.

7. Nano and Microfluidics Laboratory (NMfL) History Developed by NASA in the 1960’s. Method of controlling fluids in space.

8. Nano and Microfluidics Laboratory (NMfL) Review of Magnetism

9. Nano and Microfluidics Laboratory (NMfL)

10. Electromagnet

11. Nano and Microfluidics Laboratory (NMfL)

12. Applications of Ferrofluids Liquid seals in bearings. Used in hard drives/ o-rings.

13. Nano and Microfluidics Laboratory (NMfL) Speakers Used for and cooling around coils.

14. Nano and Microfluidics Laboratory (NMfL) Dampening Internal dampers in shock absorbers and stepper motors etc.

15. Nano and Microfluidics Laboratory (NMfL) Biomedical Application Magnetic cell separation chambers

16. Nano and Microfluidics Laboratory (NMfL) Target delivery agents.

17. Nano and Microfluidics Laboratory (NMfL) Telescopes for Astronomy Research conducted in using ferrofluids for liquid mirrors. http://www.newscientist.com/article/dn15154-morphing- mirror-could-clear-the-skies-for- astronomers.html?feedId=online-news_rss20

18. Nano and Microfluidics Laboratory (NMfL) Thank you. Questions?