Humidity Sensors from Honeywell

Honeywell is cemented traditionally strong position of the humidity sensor, expanded its series of hih. Now, developers are available humidity sensors in versions and with additional hydrophobic filter, as well as sensors for SMT-mounting. Used for measuring humidity sensors based on different physical principles and implementation of various technologies. We can distinguish four basic types of sensors: capacitive, resistive, based on tin oxide and aluminum oxide. Let us consider briefly the characteristics of each type. Of those presented four main types of measuring humidity in the best possible combination of parameter is the capacitance. It provides a wide measurement range, high reliability and low cost by using microelectronic technology. The latter allows the capacitance of a planar type thin-film method.

Due to this we have the miniature size of the sensitive element, the possibility of implementing on-chip application-specific integrated circuits for signal processing. Processability and high yield crystals provide a low cost of production of this type. Thus, for capacitive humidity measurement method is the best. We now consider the distinctive features of capacitive humidity sensors, offered to our attention a company Honeywell. The sensing element is a multilayer structure. On a silicon wafer deposited platinum film, which forms the first electrode of the capacitor. Insulator between the plates is a thermoset polymer, on top of which is made the second plate of the capacitor – the platinum film with perforations, allowing moisture to penetrate to the absorbent layer and change its relative dielectric constant of , and accordingly – and the capacity C of the capacitor.

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