The UPSICAP passive and active sensors measure ambient temperature and relative humidity. The tiny (9 mm × 8 mm) passive elements vary their capacitance with humidity and their resistance with temperature, and they are fully interchangeable without recalibration. Owing to the sensors' patented four-layer construction, condensation and water immersion have no effect on their accuracy or their response time (0.25s), according tothe company. Recently devised by UPSI, this range of ambient sensors presents long-term stability and can operate from a 0 percent to 100 percent RH, and -90°C to +85°C. MSS bi-faceT technology is also available as plug-in micromodules (pinned board-level components or housed modules with Molex milli-grid sockets) with digital output for immediate application by end customers. Versions are available for humidity only, or humidity and temperature. Output frequency varies with humidity (7.2 kHz to 5.8 kHz), and temperature is accurately indicated optionally by NTC variable resistance, linear platinum sensor, or linear voltage output consuming <1 mW. To avoid instability and inaccuracy, the capacitive humidity cell is directly built on the active substrate´s upper side, and the digital output conditioner is integrated on the reverse side. Additional modules are available with mA to 20 mA output for humidity and temperature sensing. These products are suitable for use in applications such as air conditioning (HVAC), weather measurement (radiosonde), home appliance, aeronautics, archiving conservation, military, qualification laboratories.