Microfabricated devices for the spatial and temporal control of the cellular and tissue microenvironment

The cell microenvironment is an integral component of cellular behavior. At a given moment, a cell is bombarded by signals and cues from the environment, which all are processed and integrated into specific behaviors. It is difficult examine how a particular cue affects a cell in its natural environment due to the interference of other signals. Therefore, the ability to control the microenvironment of cells and tissues is necessary to study cell interactions. Towards this end, four different devices were developed to aid in the study of cell and tissue behavior. First, oxygen-sensitive microwells were microfabricated microwells that were embedded with an oxygen responsive dye for the purpose of measuring the oxygen tension of isolated cell clusters. The device is a simple and quick method to measure the oxygen levels without disturbing the cells in culture and is compatible with high-magnification modalities. The second device is a calibration tool for fast-scan cyclic voltammetry (FSCV) that utilizes microfluidics to improve the electrode calibrations for FSCV. The µFC is simple device that switches between buffer and dopamine and this yielded electrode calibrations with faster rise times and a more stable peak current. The µFC reduced the number of external electrical components previously needed for this calibration and produced linear calibrations over a range of concentrations. The last two devices stem from a common idea – the ability to precisely control chemical delivery to cells and tissues. The automated chemical delivery device (ACDD) was utilized for the study of yeast chemotropism on agarose and was able to produce a consistent gradient that caused orientation of yeast cells towards the higher concentration end of the gradient. Lastly, an expanded ACDD was developed for a higher degree of control over chemical delivery to cells and tissues.