Picoliter Volume Flow Sensors
A portable flow rate sensor for feed back control of picoliter level dispensing and other small volume liquid handling applications.
The flow-sensor is able to measure liquid flows in the range from less than one microlitre per minute up to 100 microlitres per minute. The measurement principle is based on the evaluation of the temperature distribution surrounding a miniaturised heater warming the liquid around some Kelvin. Both the heater and the temperature sensors reside on a thin membrane passed by the liquid from both sides. This principle ensures both high sensitivity and low response time excluding environment influences. Furthermore, no significant failures will be introduced by the ambient temperature.
More details posted here: http://www.htsresources.com/electrocaloric_flow_sensors_mems_device.php