Pipette providing sampling via back-and-forth movement of the piston

A computer-readable medium having stored thereon computer-readable instructions that, when executed by a processor, cause a device to:

• (a) switch a valve to provide communication between a first chamber and an exterior of a body of the device wherein the body houses a nozzle, the first chamber, a second chamber, a channel formed in the nozzle, and a piston mounted to slide within the first chamber and the second chamber;
• (b) switch the valve to provide communication between the second chamber and the channel, wherein the second chamber and the channel are isolated from the first chamber;
• (c) slide the piston in a first direction decreasing a first volume of the first chamber and increasing a second volume of the second chamber thereby aspirating a first volume of liquid into a tip of the device;
• (d) switch the valve to provide communication between the first chamber and the channel;
• (e) switch the valve to provide communication between the second chamber and the exterior of the body;
• (f) slide the piston in a second direction opposite the first direction increasing the first volume of the first chamber and decreasing the second volume of the second chamber thereby aspirating a second volume of liquid into the tip of the device;
• and
• (g) repeat (a)-(f) until a selected volume is aspirated into the tip of the device.