Application of a microflown as a low-cost level sensor

In this paper we present a novel 'spirit level' sensor derived from a well known thermal flow sensor. The operation principle is based on the temperature difference of two identical heaters, caused by buoyancy of air. Heating as well as temperature sensing of the structures is carried out temperature-dependent platinum resistors. Due to its simplicity the sensor is easily fabricated in silicon micro-machining technology. The theory describing the sensor is presented. The first experiments, using dc signals only, show adequate sensitivity, although high-accuracy operation is hampered by thermal drift.