We demonstrate fabrication of a simple microfluidic device that can be integrated with standard electrophysiology setups to expose microscale surfaces of a brain slice in a well controlled manner to different neurotransmitters.
Abstract
We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The two-level microfluidic device is fabricated using a two-step standard negative resist lithography process 1. The first level contains microchannels with inlet and outlet ports at each end. The second level contains microscale circular holes located midway of the channel length and centered along with channel width. Passive pumping method is used to pump fluids from the inlet port to the outlet port 2. The microfluidic device is integrated with off-the-shelf perfusion chambers and allows seamless integration with the electrophysiology setup. The fluids introduced at the inlet ports flow through the microchannels towards the outlet ports and also escape through the circular openings located on top of the microchannels into the bath of the perfusion. Thus the bottom surface of the brain slice placed in the perfusion chamber bath and above the microfluidic device can be exposed with different neurotransmitters. The microscale thickness of the microfluidic device and the transparent nature of the materials [glass coverslip and PDMS (polydimethylsiloxane)] used to make the microfluidic device allow microscopy of the brain slice. The microfluidic device allows modulation (both spatial and temporal) of the chemical stimuli introduced to the brain slice microenvironments.
Protocol
SU-8 mold fabrication Master preparation The SU-8 master on silicon wafer substrate is prepared using a two-step standard negative resist lithography process. The alignment marks on the silicon wafer are removed using a razor blade as the height of these structures (located along the outer periphery of the wafer) is more than the actual device structures. The silicon wafer is then cleaned using isopropyl alcohol and dried in a stream of N2. Support pillars…
Discussion
Existing macroscale or microscale brain slice perfusion chambers are limited in terms of the spatial resolution they provide to expose brain slices with neurotransmitters. The microfluidic device technology demonstrated here overcomes this limitation using simple bioMEMS techniques. It is anticipated that the simplicity in the fabrication of the microfluidic device and the ease in integrating it with existing electrophysiology setups will allow widespread application of the demonstrated device technology. Interesting exp…
Disclosures
The authors have nothing to disclose.
Acknowledgements
Funding was provided by NIH MH-64611 and NARSAD Young Investigator Award. The authors would also like to acknowledge Adam Beagley, Mark Dikopf, and Ben Smith for their technical assistance.
Materials
Material Name
Type
Company
Catalogue Number
Comment
RC-26GPL
Tool
Warner Instruments
W2-64-0236
Low Profile Large Bath RC-26GLP Recording Chamber
SHD-26GH/10
Tool
Warner Instruments
W2-64-0253
Stainless steel slice hold-down for RC-26G, 1.0 mm thread spacing
Shaikh Mohammed, J., Caicedo, H., Fall, C. P., Eddington, D. T. Brain Slice Stimulation Using a Microfluidic Network and Standard Perfusion Chamber. J. Vis. Exp. (8), e302, doi:10.3791/302 (2007).