This Small Business Innovation Research (SBIR) Phase I project will design and build a reloadable printhead for ink-jet deposition of biological fluids into microarrays. Production of mid range microarrays (hundreds of different fluids) is not best addressed by the existing tools. Photolithography is expensive and with long turnaround time and existing single jet devices have large volumes. The reloadable printhead will fill this market segment. The first step in this project will be to optimize the geometrical dimensions of the printhead using numerical simulations and models for a low loading volume and for best operation. Special printheads will be built for evaluation and simulation verification. The second step would consist of the actual fabrication of the devices. Functionality of the fabricated printheads will be verified using a set of oligonucleotide probes designed to detect polymorphism in the Human Leukocyte Antigen (HLA) genes. Current research indicates a correlation between the class II HLA polymorphism and the occurrence of cervical cancer. Microarrays produced with a reduced set of probes will be fabricated and hybridized with prefabricated target DNA. A design of a full probe set will be made considering the use of the reloadable printhead to fabricate microarrays for investigating genetic susceptibility of cervical cancer.<br/><br/>The commercial application of this project is in the area of microarrays. On completion of the work through Phase I and Phase II, revenues are expected to be obtained through sales of the printhead and printing systems for microarray production, and through actual production .