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 temperat ure difference of two identical heaters, caused by buoyancy of air. Heating as well as temperature sensing of the structures Is carried out using temp erature-dependent platinum resistors. Due to its simplicity the sensor is e asily fabricated in silicon micro-machining technology. The theory describi ng the sensor is presented. The first experiments, using dc signals only, s how adequate sensitivity, although high-accuracy operation is hampered by t hermal drift.