BioMEMS Device Integration, Packaging and Control for BioMEMS Rubloff Research Group Accomplishments

BioMEMS Device Integration, Packaging and Control for BioMEMS Accomplishment Microfabricated SU8 on a Pyrex wafer defines the microchannel structure Patterned gold electrodes define the readily addressable assembly sites SU8-PDMS junction by pressure provides leak-tight and nonpermanent sealing Fluidic/electric ports provide transport and electric signal for biochemical assembly LabView-based control system coordinates liquid transport and electrodeposition Significance Integrated microfluidic system provides electric signal and optical access for biochemical assembly Nonpermanent sealing provides ex situ, post-process analysis Reusable packaging components Microfluidic Control System provides systematic operation process People involved Jung Jin Park, Xiaolong Luo, Theresa Valentine, Gary Rubloff Collaborations with Reza Ghodssi, Hyunmin Yi, Greg Payne, Bill Bentley Links

BioMEMS Device Integration, Packaging and Control for BioMEMS Publications X. L. Luo, A. T. Lewandowski, H. M. Yi, R. Ghodssi, G. F. Payne, W. E. Bentley and G. W. Rubloff, “Reproducible Assembly and Catalytic Activity of a Metabolic Pathway Enzyme in Reusable BioMEMS Devices”, Lab on a Chip, Submitted. J. J. Park, X. L. Luo, H. M. Yi, T. M. Valentine, G. F. Payne, W. E. Bentley, R. Ghodssi and G. W. Rubloff, “Chitosan-mediated in situ biomolecule assembly in completely packaged microfluidic devices”, Lab on a Chip, 2006, 6, 1315-1321. J. J. Park, T. M. Valentine, R. Ghodssi, and G. W. Rubloff, “Integrated Chip and Package Design for Surface-Controlled Bioreaction Processes with Robust, Reusable Fluidic Sealing“, Proceedings of MicroTAS 2005, 9th International Conference on Miniaturized Systems in Chemistry and Life Sciences (2005) Presentations J.J. Park, M.A. Powers, X. Luo, R. Ghodssi, and G.W. Rubloff, “BioMEMS Chip and Package Design for Surface-Controlled Bioreaction Processes”, American Vacuum Society 52nd International Symposium & Exhibition, Boston, MA, October 30-November 4, 2005.

Biopolymer-based BioMEMS BioMEMS refers to the application of microelectromechanical systems (MEMS) to biology. Current bioMEMS devices are either semiconductor-based or polymer-based, mostly PDMS. A biopolymer-based bioMEMS devices are created when chitosan is enlisted. The unique properties of aminopolysaccharide chitosan confer the bioMEMS device with special advantages such as reusability and low average-use cost.

BioMEMS Device Design and Fabrication Fluidic I/O Pyrex Electrical I/O Drilled holes in 4” Pyrex Au deposition and patterning patterning SU8 microchannel sidewall 500 mm Microchannel Electrode Optical micrograph Compression bolt Here is the design of microfluidic device. 6 identical microchannels and gold electrodes are fabricated on a 4“ Pyrex wafer for multiple experiments. Each microchannel has 2 gold electrodes as a working and counter electrode. There are reservoirs where fluid direction abruptly changes. And there are drilled holes in the center and edge of the Pyrex wafer for compression bolt passing through. I will explain this part in a few slides. If you see the figure on the bottom, it shows magnified view of red box. The channel width is 500 micron, height is 150 micron. (875 microliter = whole channel volume) Patterned gold electrode is located inside micro channel. And this is the optical image of fabricated microfluidic device. Top right image show fabrication steps of microfluidic device. Channels are fabricated of SU8 negative photo resist by photolithography. Upon exposure, cross-linking proceeds in-two-steps (1) formation of a strong acid during the exposure process, followed by (2) acid-initiated, thermally driven epoxy cross-linking during the post exposure bake (PEB) step. Electrode (1 mm x 0.5 mm) Pyrex Pyrex Gold SU8 Microchannel ( 500 mm) Side wall (400 mm x 150 mm)

Compression Sealing SU8 knife edge / PDMS gasket sealing SU8/PDMS compression seal Top sealing plate Pyrex Microfluidic channel SU8 Micro-knife-edge Pyrex 500 mm To show compression sealing technology, schematic cross sectional view of the microchannel is shown. A flexible thin film PDMS gasket layer is spun on the top sealing plate then is pressed against the top of the SU8 sidewalls, which act as “micro-knife-edges” that locally deform the PDMS to make a leak-tight seal. To evaluate the performance of the sealing technique and the overall microfluidic device and packaging design, we used colorful solution for visual observation. A close-up view of one of the microchannels with blue dye solution shows well-defined channel structure, two gold electrode sites at the bottom of the channel and connected to the I/O port, all-transparent materials for in situ optical examination and leak-free sealing. Transparent package allows the optical examination. Micrographs also confirm that our compression sealing technology is successfully achieved. It is very robust sealing. The sealing was ok up to 50 ml/min flow rate and pressure. This corresponds to the pressure value obtained by hagen-poiseuille (pressure driven flow) equation. Water viscosity 1 centipoise = 1 mPa·s = 0.001 N sec / m ^2 1 atm = 1bar = 1x10^5 Pa Testing flow rate: ~ 50 ml/min

Microfluidic Package Features Optical micrograph Non-permanent sealing Fluidic and electrical I/O Reusable packaging components Transparency for optical access PDMS/Top sealing plate I/O ring Microfluidic device Top compression plate Bottom plate Fluidic I/O Electrical I/O Optical micrograph Microfluidic channel Fluidic I/O Electrical I/O This figure on the left shows schematic side view of packaging system. Microfluidic device is inserted into the package. Flexible pdms layer is put over the microfluidic device. By compression action, robust fluidic sealing and fluidic connection from external source to the microchannel is achieved. For fine tuning of the force distribution, set screws are provided in the top compression plate. These can be used to modulate the deflection of PDMS layer to optimize the fluidic sealing. This is a exploded view. A I/O ring carries fluidic I/O connectors, delivering fluids and current through the package to the microfluidic device. Importantly the package provides non permanent sealing for ex situ analysis. It is reusable and we can rapidly exchange microfluidic device for next experiment.

BioMEMS Device and Control System Water, PBS, Chitosan …… PC with LabView Flow Control Electric signal Control Valve Micropump Fluid flow Counter electrode Chitosan Power supply Products or waste waste (c) Fluidic I/O Electric I/O Channel Electrode (b)