Nanofluidic flowmeter using carbon sensing element

Abstract

The field of nanofluidics dealing with nL fluids is growing, and sensors for monitoring ever smaller flow rates (/spl sim/nL/min) are needed. This paper presents a new, sensitive micromachined thermal sensor for measuring flow rates. The integrated sensor uses a high-TCR (temperature coefficient of resistance) carbon sensing element obtained from ion-implanted parylene. The ion-implanted carbon element has a high temperature coefficient of resistance of -2%//spl deg/C and is embedded in a freestanding microchannel suspended from the substrate. The developed sensor has been characterized for flow measurements with a volumetric flow sensitivity of 380 /spl mu/V/(nl/min) under a constant current bias with a power consumption of only 28 /spl mu/W. To our knowledge, this is the first such nanofluidic carbon flow sensor and its sensitivity is better than any of flow sensors reported to date.