A MICROFLUIDIC MICROELECTRODE ARRAY FOR EXTRACELLULAR RECORDINGS AND FOCAL STIMULATION OF BRAIN SLICES Ading Scott 1* , Matthew Becker 2 , William J. Moody 2 and Albert Folch 1 1 Department of Bioengineering, University of Washington, USA and 2 Department of Biology, University of Washington, USA ABSTRACT We present a microfluidic multi-electrode array (MEA) for studying development in mouse cortical slices. The device is designed to facilitate integrated multimode measurement with the capability to perform simultaneous multi-site extracellular recording, electrical stimulation, and focal chemical stimulation. It is compatible with brightfield and fluorescence micros- copy, enabling simultaneous electrical, optical, and chemical manipulation and characterization of slices with high spatial and temporal precision. KEYWORDS: Electrophysiology, Multielectrode Array, Focal Stimulation, Cortical Slices INTRODUCTION Spontaneous synchronous activity (SSA) during early stages of brain development is important for processes such as cir- cuit formation and cortical neuron migration [1]. Although this activity has been observed for some time, the mechanisms of SSA and its influence on development are not well understood, in part due to the difficulty of characterizing the complex temporal, spatial, and biochemical characteristics of the process. Techniques for simultaneously measuring and manipulating electrical, optical, and chemical properties of tissue are needed to elucidate the mechanisms of SSA. Calcium imaging can be used to provide information about global behavior of the tissue or to isolate activity of specific neuron sub-populations, how- ever it is an indirect measure of electrophysiology and has very limited temporal resolution due to the slow nature of calcium and dye kinetics. Electrical recordings offer exceptional temporal resolution and more direct measurement of activity, how- ever typical recordings have limited spatial resolution and can be difficult to interpret. Moreover, these techniques should be combined with controlled focal chemical stimulation to determine the spatial and temporal influence of specific neurotrans- mitters. Traditional tools such as electrophysiology recording glass pipettes, calcium imaging, and multi-electrode-arrays (MEAs) offer only a subset of these functions. Microfluidic platforms have shown promise for enhancement and automation of electrophysiology measurements. Patch- clamp chips have demonstrated that high quality electrical recordings can be obtained using a microfluidic chip platform [2,3]. Microfluidic perfusion and focal chemical stimulation systems have been combined with traditional electrophysiology techniques such as recording pipettes and Ca imaging, demonstrating the potential utility of microfluidics for controlling the biochemical environment of brain slices [4]. We introduce a polymeric microfluidic MEA on a chip that enables simultane- ous high quality multi-site electrical recording and stimulation, imaging, and focal chemical stimulation. EXPERIMENTAL Figure 1: Side-view schematic (a) and optical micrograph (b) of electrochemical electrode array device. Photographs of de- vices without (c) and with (d) focal chemical stimulation capabilities are shown. 978-0-9798064-4-5/μTAS 2011/$20©11CBMS-0001 42 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences October 2-6, 2011, Seattle, Washington, USA