SUMMARY Tissue clearing is a powerful technique that renders large biological samples optically transparent and allows 3D visualization of wide-brain molecular anatomy. To help disseminate this technology, Translucence Biosystems developed a Mesoscale Imaging System™ and, using previous SBIR NIH support, an analytical software package for advanced analysis of brain samples, 3TKTM. While complete solutions exist for imaging and analysis of cleared samples, no complete solution exists for the highly labor intensive and error prone tissue clearing process. Here Translucence Biosystems introduce Clearbot™, an automated system for sample clearing and immunostaining that will complement previous Translucence devices and complete a pipeline for reliable brain- wide molecular anatomy of intact rodent and human tissues. In this Phase I proposal, Translucence Biosystems will build a prototype of Clearbot™ and demonstrate automated brain tissue clearing for whole-brain analysis. Specific aims: Aim 1: Assemble and evaluate a Clearbot prototype: the basic functionality of the prototype developed by an engineering consultant will be evaluated for functionality, robustness, energy consumption, and overall reliability. Aim 2: Evaluate the utility of Clearbot for automated clearing and immunostaining of intact brains: quality and repeatability of tissue clearing will be evaluated using the prototype assembled in Aim 1. Multiple mouse brains will be cleared and immunostained with Clearbot and benchmarked to manual processing done in parallel. This Phase I project will demonstrate the feasibility of developing an automated device that is comparable to or better than manual clearing. Following success of this Phase I feasibility testing, future developments will advance the prototype to a flexible, commercial-grade system with a robust and simple user-interface, helping researchers apply this game-changing technology to their research questions.