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Implementation of BioMEMS for Determining Mechanical Properties of Biological Cells Svetlana Tatic-Lucic, Markus Gnerlich ECE Department, Lehigh University, Bethlehem, PA, 18015, U.S.A. ABSTRACT This paper describes the implementation of a custom-made bio-microelectromechanical system for determining mechanical properties of biological cells, which is used for the measurement of mechanical properties of fibroblasts. Our system consists of several subcomponents: (a) actuator which deforms the cell in pre-determined, step-wise fashion, (b) force sensor that measures force applied onto the cell, (c) set of dielectrophoretic (DEP) electrodes for positioning cells in the desired position, (d) temperature sensors and (e) heater. Preliminary results of the mechanical properties of NIH3T3 cells have been determined using this tool and our cell compression techniques. INTRODUCTION Even though microelectromechanical systems (MEMS) have been researched and developed for several decades now, only relatively recently has their full potential in the fields of medicine and biology been recognized and exploited. Within that framework, their applications are particularly attractive in cell biology, because of the nearly perfect compatibility of their sizes, as well as the simultaneous flourishing of both miniaturization science and bioengineering. Determining mechanical properties of biological cells proved to be a very fruitful BioMEMS targeted application, but it was a challenge because of the lack of techniques that would be capable of executing this task accurately and efficiently on more than one individual cell at the time. The methods to study cell biomechanics can be roughly divided by the techniques used to probe the cells: (a) substrate stretching or stretching a matrix with embedded cells, (b) deflection of micropillars in contact with cultured cells, (c) deformation of a cell using optical or electrical based dielectrophoresis (d), compressing or stretching the cell with microplates and microsprings, (e) aspirating the cell in a micropipette, or (f) locally deforming the surface of the cell with a microneedle, AFM, microbead, etc. Excellent reviews of the use of MEMS to study cell biomechanics are readily available [1] [2] [3] as well as summaries of the relationship between cell biomechanics and disease [4]. Many of these techniques have been reported as proof-of-concept and have been further developed to produce interesting scientific findings about cell mechanical properties. The next step in the evolution of BioMEMS is to produce high-throughput biomedical instruments that are able to test each cell in large populations of cells and produce statistics about the population. In these high-throughput schemes, the key problems are: (1) positioning the cells quickly and

accurately in the “active area” of the testing device, and (2) using MEMS sensing technologies compatible with the cell environment. Microfluidics may be able to address the first problem. Already, research which combines microfluidics with optical DEP h