Initial investigation of SU-8 photopolymer as a material for non-invasive endothelial cell research platforms S. Westwood *a , A. Gojova b , B. Kuo b , A. I. Barakat b , B.L. Gray a a Dept. of Engineering Science, Simon Fraser University, 8888 University Ave., Burnaby, BC Canada V5A 1S6 b Dept. Of Mechanical & Aeronautical Engineering, University of California, One Shields Avenue, Davis, CA USA 95616-5294 ABSTRACT This paper presents a preliminary investigation in the usage of the micromachining polymer material SU-8 for the non- invasive shape control and functional study of vascular endothelial cells (ECs). We previously demonstrated a silicon and glass modular microinstrument platform that allowed for a wide range of EC functional response studies. However, we expect SU-8 to provide a more versatile fabrication technology and material for microchannel fabrication and instrumentation, since it is capable of achieving high aspect ratio sensor-compatible structures through simple photopatterning. In this paper, SU-8 microchannels were fabricated on glass slides for straightforward optical observation and biological sampling. Channel widths ranged from 50 to 210 µm, length varied from 100 to 2100 µm, with depth fixed at 100 µm. We plated bovine aortic endothelial cells (BAECs) in the microchannels and used image analysis to determine cellular elongation and orientation. Similar to silicon-on-glass microchannels, the cells become more elongated and oriented along the microchannel axis as the width of the microchannel decreases. Initial results indicate cells plate in the microchannels and on the SU-8 surfaces, whereas in a previous silicon microchannel study, cells plated exclusively on the glass bottom surfaces. This finding has implications for SU-8 as a structural material for microchannel instrumentation. Keywords: Cell platform, cell-based systems, SU-8, endothelial cells, microchannels 1. INTRODUCTION Lab-on-a-chip (LOC) systems represent a sizeable advance in the ability for clinicians and researchers to quickly and cost effectively investigate issues like disease detection, DNA testing, and blood analysis [1]. The shrinking of the conventional lab into an LOC system enables smaller required fluid samples (µL to sub-µL), better process control, and substantial parallelization, which allows for high throughput analysis [2]. Microfluidics has moved beyond the simple ability to make networks of interconnecting channels to the realm of complex microinstruments for functional studies of cells and other biological samples. Such microfluidic instrumentation can be used to realize cell platforms designed specifically for cellular study; that may contain fluidic, electronic, mechanical components, or a combination thereof. Currently, most cellular study is performed in vitro. Cell platforms help to mimic in vivo conditions while providing unique instrumentation for functional cell studies. For example, by incorporating fluid flows, cell platforms can mimic the shear stresses observed in the vascular system [3], or can be fitted with microcantilevers for measuring electrical impedance of a single cell [4]. In addition, cell platforms may be designed as modular to examine various cellular properties via interconnect between microchips [5], simultaneously streamlining cell analysis and reducing costs. Atherosclerosis, or hardening of the arteries, is a disease that can lead to heart attack and stroke [6] and is the leading cause of mortality in the western world [7]. The development of atherosclerosis is characterized by dysfunction of the endothelium, the cellular monolayer lining the inner walls of all blood vessels. Early atherosclerotic lesions develop preferentially in regions of arterial branching and curvature, and these regions are associated with round, or cuboidal, endothelial cells (ECs). In contrast, arterial regions away from branches are associated with highly elongated ECs and * swestwoo@sfu.ca ; ph: 604-291-4371; fax: 604-291-4951 Microfluidics, BioMEMS, and Medical Microsystems V, edited by Ian Papautsky, Wanjun Wang, Proc. of SPIE Vol. 6465, 64650S, (2007) · 0277-786X/07/$15 · doi: 10.1117/12.702280 Proc. of SPIE Vol. 6465 64650S-1