Towards low-cost printed flow sensors

Air conditioning systems need permanent monitoring of the mass and energy flows in the air ducts to assess their proper operation and detect and correct changes that may occur over time. This is a prerequisite for energy efficiency and demanded by recent legislation like the Energy Performance of Buildings Directive issued by the European Union. Such distributed monitoring systems require low-cost and robust flow sensors that need not be extremely precise, but should give a good indication of the flow distribution within the air conditioning system. In this paper we present a technology feasibility study to implement flow sensors based on thick-film thermopiles printed by silk screen printing on a plastic carrier film. Finite element simulation studies prove the viability of the sensor concept, and first samples of the printed Ag-Ni thermopiles demonstrate the feasibility of the production technology.