1. ME-381 Dec. 5Xiaohui Tan, Rui Qiao A STUDY ON CELL ADHESION BY USING MEMS TECHNOLOGY Rui Qiao Xiaohui Tan ME-381 Dec. 5

2. Xiaohui Tan, Rui Qiao Presentation Outline Introduction and motivation Current MEMS systems in this area Our idea Conclusion

3. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Meaning of this research Understand the evolution of tissues and organs Manipulate the adhesion http://health.allrefer.com/

4. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Why MEMS? Cells and MEMS are in the similar scale Cells can survive on artificial surfaces The microfabrication technique is relatively mature

5. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Some of Current Models Single MEMS sensor A bed of microneedles

6. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Model I In-situ adhesion studies of a single living bovine endothelial cell using MEMS sensor The MEMS sensor consists of a cantilever beam made of Single Crystal Silicon (SCS), 1200 µm long x 11.5 µm deep x 4 µm wide, coated by a thin native silicon dioxide layer.

7. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Experimental System

8. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Experimental Result The adhesion properties of a single living bovine endothelial cell was studied. Quantitatively it has been found that a focal adhesion site, prior to failure, applies 37 nN of force onto the MEMS sensor.

9. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Focal adhesion Procession of a breaking filopodia

10. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Discussion This work is one of the earliest studies on cell adhesion. The device is quite simple and they can measure the magnitude of the adhesion force This device doesn’t have much control on the contact of the cell and the beam Can only measure the force form on contact region

11. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Model II Cells lying on a bed of microneedles: An approach to isolate mechanical force

12. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Strategy A strategy to independently manipulate mechanical compliance and surface chemistry: for small deflections, the deflection is directly proportional to the force applied by the attached cell

13. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Fabrication

14. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Fabrication Cont’d

15. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Result Both the magnitude and direction of the adhesion forces can be obtained

16. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Advantages Less assumptions Can capture the magnitude also the direction of the force at the same time The mechanical property of the substrate can be easily changed without change the material of the substrate

17. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Disadvantage The resolution of this model only in micrometer scale while the focal adhesion is also in this scale Improving the resolution means increasing the density of posts in the array, which leads to a high requirement of deflection measuring precision

18. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Our idea Use the membranes to measure the focal adhesion forces. As the deformation is vertical, the dots could be very close without any interactions h

19. ME-381 Dec. 5Xiaohui Tan, Rui Qiao MEMS System Cell Membrane Fabricate an array of membranes on a silicon wafer. Those membranes will deform under cell adhesion

20. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Fabrication process wafer1wafer2 hydrophobic alkanethiol protein-resistant hydrophilic alkanethiol Photolithograph Cast PDMS Electrical etching Microcontact printing

21. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Measurement Use optical readout to detect the displacement of each membrane

22. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Discussion Advantage –Can improve the spatial resolution –Can determine the adhesion force from each focal contact site. Disadvantage –Cannot get the direction of the force –Readout device is complicated

23. ME-381 Dec. 5Xiaohui Tan, Rui Qiao Conclusion Introduced two MEMS system already used. Provided a new device, which needs experiment to prove With the size of device decreasing, NEMS system will act important roles in this area

24. ME-381 Dec. 5Xiaohui Tan, Rui Qiao ACKNOWLEDGEMENT Professor Horacio D. Espinosa TA: Yong Zhu Team members