Fabrication and testing of a SU-8 thermal flow sensor
ABSTRACT In this work, a microthermal flow sensor integrated in a completely polymeric based microfluidic chip is presented. The fabrication process is based on photolithography of SU-8 layers to pattern the fluidic channels, surface treatment processes in order to improve adhesion of metal layer on top of the polymer, and the use of an adhesive bonding of two patterned SU-8 layers, allowing an easy packaging and integration with other SU-8 based devices like micropumps, microvalves, etc. Characterization of the device shows its successful performance detecting flows in the order of tens of μl/min, working at heater temperatures from 60 °C down to 40 °C. Moreover, the sensor exhibits a linear response at flows below 25 μl/min and the detection of volumes in the range of nanoliters. Such characteristics of the sensor are of great interest for its use in biological applications.
Full-textDOI: · Available from: Luis J Fernandez, Apr 15, 2015
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ABSTRACT: In this paper, the design, fabrication, and response characteristics of the micromachined flow sensor were presented. The flow sensor comprising of two hot wires detects the flow rate by measuring the heat transfer of the two hot wires with mesh-membrane structure, which were supported by double-layer cantilevers and suspended in the flow channel. Polydimethylsiloxane instead of glass was used to fabricate the flow channels and seal the flow sensor at the room temperature, owing to its intrinsic structural economic, simplicity, and reliability. Moreover, the fabrication process of the flow sensor can avoid a high-temperature bonding process, resulting in higher sensitivity. The experimental results have indicated that the proposed flow sensor exhibited a linear response for flow rates up to 10 sccm, and the resolution of the flow sensor was less than 0.1 sccm. The four-cycle experiments suggested a reliability and repeatability of the proposed flow sensor.Journal of Microelectromechanical Systems 06/2013; 22(3):723-729. DOI:10.1109/JMEMS.2013.2242311 · 1.92 Impact Factor
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ABSTRACT: This paper presents a micro flow sensor based on two heaters acting also as temperature sensors. The two heating/sensing elements of the sensor are arranged in the diagonal arms of the Wheatstone bridge and suspended in an airflow channel by solid beams. The length of the heater and the distance between the heaters were optimized by numerical modeling. The solid beams were fabricated by a heavily doped p-type silicon layer and a silicon nitride layer, which was immune to airflow disturbances and thermal noises. The experimental results indicated that the micro flow sensor with a high sensitivity of 0.30 mV/(ml/min) exhibited an excellent linear response within the range of 0.5–6 sccm. This micro sensor demonstrated great potentials in biological applications, micro gas chromatography systems, medical instrumentation and process control.Sensors and Actuators A Physical 04/2013; 193:25–29. DOI:10.1016/j.sna.2013.01.010 · 1.94 Impact Factor
Microsystem Technologies 01/2015; DOI:10.1007/s00542-015-2423-9 · 0.95 Impact Factor