The present invention discloses a method and apparatus for testing the operational capability of flexure area equipped sensors especially those made of micromachined silicon. A thermal actuator beam is provided to bridge the structures which are joined by the flexure area. During the test, the beam's temperature is changed relative to that of the flexure area so as to provide a differential expansion or contraction. The result is that the flexure area bends and conventional bending sensors for the flexure area can sense the amount of bend. By comparing the actual amount of bend sensed with the amount expected from the temperature change applied to the beam, the operational capability can be determined.

A differential pressure transducer is provided in which first and second diaphragms are formed within a block of material, such as monocrystalline silicon. Each diaphragm carries a support for a bridge. The supports are offset from the center of the diaphragms such that deflection of the diaphragms imparts a degree of lateral motion to the respective support. The bridge is held within an evacuated cavity and the resonant frequency of the bridge is a function of the difference in pressure action of the diaphragms.

A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

An optically coupled resonant pressure sensor includes a deformable diaphragm and an optically coupled resonator fixedly attached to the deformable diaphragm. The resonator includes a resonator body and a laterally offset photodiode adjacent to the resonator body. The resonator is driven by an electric field generated between the laterally offset photodiode and the resonator body when an incident light strikes the photodiode. Pressure applied to one side of the deformable diaphragm causes a shift in a resonant frequency of the resonator. Also disclosed are a method and system for determining pressure.