US Patent 9360164 Particle manipulation system with stay-wet algorithm

A MEMS-based particle manipulation system which uses a particle manipulation stage and a sensor to detect when the sample volume is exhausted or nearly exhausted. The sensor sends a signal to a fluid control means that reverses the pressure between one of the output channels and the input channels, to keep the surfaces wet with a volume of the sample fluid. This volume can be maintained in the channel until an operator intervenes, or it can be repeatedly shuttled back and forth between the input channel and an output channel. By keeping the channels wet, material from the sample stream does not become adhered to the channel walls, which might otherwise irreversibly change or damage the device.