Abstract: The invention refers to a multifunction sensor system and a corresponding method for supervising room conditions, comprising a temperature sensor, a humidity sensor, an ultrasonic transducer for emitting ultrasonic waves and being positioned in a fixed distance to a reflecting fixed reflective surface. For calculating the CO2 concentration in the supervised room, the time of flight of ultrasonic waves between the transducer and the fixed reflective surface is measured, and the CO2 concentration is calculated from the output values of the temperature sensor, the humidity sensor and the measured time of flight.

Abstract: A transducer (800) is provided where a membrane (830) is formed over a front substrate (615); and a piezoelectric layer (820) is formed over the membrane (830) at an active portion (821) and peripheral portions located adjacent the active portion (821). A patterned conductive layer including first and second electrodes (840, 845) is formed over the piezoelectric layer (820). Further, a back substrate structure is provided having supports (822, 824) located at the peripheral portions adjacent the active portion (821). The height (826) of the supports (822, 824) is greater than a combined height (828) of the patterned piezoelectric layer and the patterned conductive layer. Many transducers may be connected to form an array, where a controller may be provided for controlling the array, such as steering a beam of the array, and processing signals received by the array, for presence or motion detection and/or imaging, for example.