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This work describes the design of a holder for a quartz crystal microbalance for space application. The main objectives of the conceived system are to hold the quartz crystal providing adequate support in the expected mechanical and thermal environments, and to assure the functionalities of the instrument, i.e. measuring the oscillation frequency and the crystal temperature or heating the crystal during regeneration phases. A kinematic mounting has been designed to be manufactured by stereolithography because this technology allows achieving high spatial resolution and complex shapes that are needed to implement an easy assembling and mounting of the holding system. Moreover, the 3D printing technology would provide a cost-effective solution even for small series production.

This research activity investigates the temperature-frequency relationship of quartz crystal microbalance for thermogravimetric analyses in space. The microbalance configuration is innovative because of built-in heater and temperature sensor made by metallic films deposited on the crystal. This configuration allows direct temperature measurement over the sensing area, an essential feature for a thermogravimetric sensor that must operate in a wide temperature range, in transient conditions and/or with unknown external heat flux. In fact, beside the deposited mass, the oscillating frequency of the crystal strongly depends on the temperature of the electrode area. In this work, the effect of the temperature on the microbalance frequency has been addressed for the case of uniform distribution, in the temperature range from −20°C to 100°C but the methodology hereafter presented, can be applied to vider temperature ranges where a specific microbilance might be required to operate.

Quartz crystal microbalances have been used as measuring and monitoring devices for particle deposition on sensitive surfaces such as optical mirrors, thermal radiators, solar arrays, and other equipment used in space exploration. Moreover, microbalances have been applied in space to perform thermo-gravimetric analyses in order to infer about the type of volatile and condensable material. When the object of contamination monitoring is an intrinsically cold surface, e.g. a radiator, an effective cooling is required to achieve the same (or slightly lower) condensing temperature. The cooling problem of the microbalance sensing area has found promising solution from the use of thermoelectric coolers, the only compact and lightweight devices that can be housed in a typical microbalance envelope. Nevertheless, performance of the thermoelectric element at low temperature is a known issue so that restricts most applications above −40°C therefore there is a lack of data about performances below that temperature and characterization in expected environment is generally required. Thus, in this work cooling performance of commercial thermoelectric elements has been assessed at low temperature along with its survival to thermal cycling in off condition, in order to assess its applicability for the space borne microbalance under development.