The Top Chip is designed for use with the Resealable Chip Interface (Part No. 3000305) and a Base Chip. It features an integrated elastomer gasket which seals with the Base Chip. By using the Linear Connector 4-way (Part No. 3000024) liquid can be pumped into the chip and across the surface of the Base Chip. The chip features four input streams which can be connected with one output stream. This allows the positions of the streams to be controlled and the potential generation of a concentration gradient.