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We assess the impact of the fabrication-related variability of the thickness of the effective gap layers on the transmission (TX) and reception (RX) performance of a reverse-fabricated CMUT array by means of finite element analysis (FEA). The extreme values of the thickness of the passivation layers and of the cavity height, obtained by interferometry measurements during in-line wafer inspection, are applied to the simulated design of a reverse-fabricated CMUT array of circular cells. The analysis follows a 2-by-2 factorial approach to evaluate the variability of the TX and RX sensitivity amplitude, phase, and bandwidth caused by the fabrication tolerances, and compute the main effects and interactions of the effective gap layers.

This work reports on the investigation of the element beam pattern of a 2D CMUT spiral array by finite element analysis, aiming at assessing the effect of the transducer integration with the ASIC on the fluid-coupled transmission performance. The array element acoustic directivity is computed for the clamped substrate condition and compared with that obtained by coupling the transducer with a Benzocyclobutene (BCB) layer, used as an underfill between the CMUT and the ASIC. Different packaging solutions are considered and their effect on the element directivity is compared. The CMUT spiral array element is experimentally characterized in water-coupled transmission operation using a hydrophone to validate the finite element simulation.

The increasing spread of pervasive technology has led to the fast development of human-centered connected systems, such as cloud-based voice services, assisted driving systems, domotics control systems, personal digital assistants. The user interacts with these systems by speaking to an artificial intelligence, which interprets the speaker's requests and takes decision accordingly. In such scenario, the real-time collection of personal information from the speaker's voice is a key-function to develop in order to offer personalized services. Gender is part of the basic information needed to customize the user experience. Furthermore, knowledge about the sex of the speaker also proves useful in automatic speaker recognition and voice-based identity recognition systems, since it restricts the search space to individuals of one gender, thus speeding up the system response. Therefore, gender recognition techniques through speech analysis have largely attracted the researchers' attention. Speech analysis is usually performed by extracting some features from the speech signal that can be affected by additional factors other than the gender: emotional state of the speaker, for example, is conveyed in the speech by altering some parameters that take part to the gender recognition process. At the same time, the outcome of emotion recognition systems based on speech analysis can be affected by the speaker's gender. This paper briefly summarizes the techniques used to perform gender recognition through speech analysis and proposes a practice to take gender into account in emotion recognition methods.

Due to the growing demand for humidity control systems, there is a need for small, cheap, accurate and reliable sensors for air relative humidity (RH) measurements. In this paper, a resonant air relative humidity sensor is presented. The sensor is based on a quartz crystal coated on both surfaces with a hygroscopic polymer. Due to the adsorption of water molecules, the polymer mass increases accordingly with the surrounding air humidity, causing the decrease of the device resonance frequency. By measuring the sensor resonance frequency, an accurate RH measurement can be obtained. Experimental results are shown, comparing the fabricated sensor behavior with a commercially available RH sensor.