A STUDY ON CELL ADHESION BY USING MEMS

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

Presentation Outline • • ME-381 Introduction and motivation Current MEMS systems in this area Our idea Conclusion Dec. 5 Xiaohui Tan, Rui Qiao

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

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

Experimental System ME-381 Dec. 5 Xiaohui 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 n. N of force onto the MEMS sensor. ME-381 Dec. 5 Xiaohui Tan, Rui Qiao

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

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

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

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

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

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

Fabrication process • • Photolithograph wafer 1 Cast PDMS Electrical etching Microcontact printing wafer 2 hydrophobic alkanethiol protein-resistant hydrophilic alkanethiol ME-381 Dec. 5 Xiaohui Tan, Rui Qiao

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

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

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