Optimization of T-Cell Trapping in a Microfluidic Device

Group #19

Jeff ChamberlainMatt Houston

Eric Kim

MEMS- MicroElectroMechanical Systems

• Batch Fabrication Processes

• Cell Traps– High-throughput

experimentation– Complex biochemical

analysis– Single cell analysis– Reagent

conservation– Quick environmental

changes

Cell Trapping Basics

Reagent #1

Reagent #2

Cells / Media

Trap arrays:

Our Project

• Maximize trap efficiency by improving upon current trap designs.– Trap Efficiency : maximized number of

traps with 1 cell/trap

Cell Viability ResultsFlow Rate = 100 nl/min

Flow Rate = 250 nl/min

SolidWorks® Rendering of a Single Well

Picture of Well Array

• Square or rectangular shaped well of any depth

• Thousands of mirrored wells in one etching

• Front Surface Mirrors with high reflectivity

• Nearly orthogonal views of specimen

200 um200 um

Background & Motivation

Three Dimensional Image Information May Be Important for Biological Studies

• Chemotaxis• Developmental Biology• Cellular Division• Pinocytic Loading • Volumetric Measurements

Our System is Constructed From Silicon Wafer <100>

Methods: Fabrication

Silicon Wafer Silicon Wafer <100><100>Grow SiOGrow SiO22

Spin Coat Mask Spin Coat Mask LayerLayerPattern with Pattern with PhotolithographyPhotolithography Etch with HFEtch with HF

Remove Remove PhotoresistPhotoresist

Etch with KOHEtch with KOH

Coat with Platinum Coat with Platinum or Aluminumor Aluminum

Cutaway ViewCutaway View

SolidWorks® Rendering of a Single Well

Results: Dictyostilium Extrusion

AA

BB

CC

AA

BB CC

Primary ImagePrimary Image

ReflectionReflection

Primary ImagePrimary Image

ReflectionReflection

Reflection of Reflection of the Reflectionthe Reflection

ReflectionReflection

ObjectiveObjective

Coupling Microfluidics With the Pyramidal Wells

Si Wafer

Cross Section of One Well

PDMS

Flow

Flow

PDMSGlass

Pyramidal Well Dimensions

10 20 30 40 50

25

50

75

100

125

150

depth_min = 3.22728 cell_radius

outside_dim = 3.48504 cell_radius

Assuming:

0.5 base = 1.2 cell_radius

Micromirror Well Dimensions

Cell Type Cell Dimensions (um) Minimum Required Depth (um)

Outside Dimensions for Min Depth (um)

T-cells 5 diameter 8.0682 17.4252

Jurkats 10 diameter 16.1364 34.8504

Dendritic Cells 10-20 diameter 16.1364 - 32.2728 34.8504 - 69.7008

Dicti 10-20 diameter 16.1364 - 32.2728 34.8504 - 69.7008

Myocyte 15 by 100 24.6737 54.9399 by 37.9399

10 20 30 40 50

25

50

75

100

125

150

Future Directions

• Single Cell Design– Desire single cell per well for optimal imaging– Possibly controllably coupled with another

As opposed to…

Future Directions

?

• Single Cell Design– Desire single cell per well for optimal imaging– Possibly controllably coupled with another

Future Directions

• Flow Modeling– Design a more efficient trapping system– Use flow data to design trap design that will keep cell in well

?

Future Directions

• PDMS-mirror bonding– Questions to whether the PDMS will bond to the mirror array

– Use SU-80 and glass cover slip with a PDMS external flow system?