Pinching channels for fractionation of fragmented samples

A method of separating a sample material into a plurality of separated components and isolating one or more of the separated components in a device, the method comprising:

• loading a sample material into a loading well in fluid communication with a separation channel of a device;
• separating the sample material into a plurality of separated components in the separation channel, the separated components forming a stream;
• transporting the stream of separated components into a switching region of the device;
• transporting first and second buffer streams into the switching region on either side of the component stream such that the first and second buffer streams constrain and elongate the component stream as it is transported through the switching region;
• directing a first portion of the stream of separated components, a first portion of the first buffer stream, and a first portion of the second buffer stream out of the switching region and into a waste leg of the device;
• directing a second portion of the stream of separated components, a second portion of the first buffer stream and a second portion of the second buffer stream out of the switching region and into a collection leg of the device, the collection leg having a first end and a second end;
• directing a third portion of the stream of separated components, a third portion of the first buffer stream and a third portion of the second buffer stream out of the switching region and into the waste leg of the device;
• and
• collecting a separated component from a collection well disposed in the collection leg between the first and second ends of the collection leg.