A microfluidic device for marking small tissues

Microfluidics focuses on the handling and analyzing of fluid and biological materials in structures ranging from 10-1000 um. Microfluidic devices, which can be rapidly prototyped within hours, decrease the cost of research by minimizing reagent use and enabling multiple experiments in parallel. Applications of microfluidic technology include identifying diseases and providing point of care diagnostics. In this project, a microfluidic device was developed for marking small tissues. The inspiration of this project was Drosophila (fruit fly) brains used in the study of Parkinson’s disease. Currently, lines of Drosophila are crossed, and the offspring’s brains are removed and analyzed. Dopaminergic neurons on the brains are marked in Eppendorf tubes using a three-chemical process with incubation and wash steps. The brains are removed and studied to see if the genetic cross caused degradation of the neurons. Conventional procedures are timeintensive, require expensive reagents, and are only performed in small batches because the tissues are delicate. The microfluidic prototype incorporated critical design factors for use with Drosophila tissue and in this study we demonstrated operation with a sample tissue. The device includes wells for the brains and serpentine channels to promote mixing. Five brains could be tested simultaneously on a microscope-slide sized device. The delicate tissue is protected because brains are separated into different wells and the flow rates are low. This design is molded into an elastomer and sandwiched between two acrylic plates to enclose the channels. This allows for removal of tissue after microfluidic marking for testing, device reuse, and minimal reagent consumption. Because multiple tests can be performed in parallel the process is also less labor intensive. The successful proof of principle of the device for a sample tissue has been demonstrated and suggests it could be effective for marking Drosophila or other small tissues