The 10th International Conference on Miniaturized Systems for Chemistry and Life Sciences (μTAS2006) November 5-9, 2006, Tokyo, Japan 4-9903269-0-3-C3043 © 2006 Society for Chemistry and Micro-Nano Systems 1507 A CELL-RELEVANT MICROGRADIENT ENVIRONMENT Thomas Frisk 1 , Susanna Rydholm 2 , Helene Andersson 3 , Hjalmar Brismar 2 , Göran Stemme 1 1 Microsystems Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden 2 Cell Physics, Royal Institute of Technology 3 Nanobiotechnology, Royal Institute of Technology tfrisk@kth.se Abstract A device for microgradient cell environment has been designed, built and successfully evaluated with gel embedded MDCK cells. Keywords: gradient, cells, culture, 3D 1. Introduction With confocal microscopy new knowledge in cell physiology is acquired daily. However, most cell assays today are carried out either as multiwell plate assays, or in standard petridish assays. These two methods have different features and foci, but they have in common the large amount of cells submitted for treatment and imaging. In order to study only a few cells on a more detailed level[1, 2] in a relevant context, we have designed, built, and evaluated a microfluidic system. It features 1) immobilization of cells in three dimensions, 2) transportation of cell nutrients and treatments as well as removal of residual products, 3) an extremely stable and physiologically relevant gradient of chemical concentration distribution around the cell. Previous efforts in this field by our group revealed a few very important issues, indicating that microfabrication would be the enabling technology for experiments on cells in asymmetric environments. 2. Experimental The ‘micromolar per micrometer’ gradient chip was manufactured with standard microfabrication methods including two soft masks and photolithography, DRIE and anodic bonding of 300 μm thin silicon to 170 μm thin glass. The smallest cell assay chamber measures length 100 μm by width 100 μm and height 50 μm. Figure 1. Gel cavity before glass lid bonding and backside hole etching.