Nanostructured thermomechanical cantilever switch
OwnerWilliam N. Carrinventor
Life of this patent
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Abstract
A thermally-sensitive cantilever sensor switch with a bimorph structure based on phononic cantilever structure. Phononic structure increases switch sensitivity to incident absorbed radiation. In embodiments the zero power switch is sensitive to ambient temperature and/or incident absorbed radiation. In embodiments, multiple switches are configured within a spectrometer to provide a means of monitoring toxic components within a media of interest such as smokestake effluents and hot emitters. The switch may be structured with sensitivity to incident radiation within wavelength bands ranging from ultraviolet (UV) to MHz.
Claims40
A thermomechanical cantilever sensor switch (TCSS) comprising at least one cantilever with bimorph structure, actuated in response to internal cantilever temperature, wherein:
- each cantilever is suspended from a surrounding substrate;
- each cantilever provides an electrical connection between an actuated metal contact disposed on the distal end of the at least one cantilever and a stationary electrical contact disposed on the surrounding substrate;
- each cantilever comprises first and second isothermal, planar bimorph elements with differing thermal coefficients of expansion, thereby providing a means for actuation of the distal end of the cantilever in the plane of the surrounding substrate in response to internal temperature of the bimorph elements;
- each cantilever comprises phononic structure disposed within the length of the cantilever providing enhanced thermal isolation for the isothermal, planar bimorph elements with respect to the surrounding substrate;
- the phononic structure comprises structural sites separated by distances less than the mean free path (mfp) length of at least some heat conducting phonons, wherein thermal conductivity within the phononic structure is reduced;
- the phononic structure provides an increase in the ratio of electrical conductivity to thermal conductivity within the length of the phononic structure;
- and
- the sensor switch TCSS status is determined by a physical gap between two metal contacts, wherein at least one metal contact is an actuated contact disposed on the distal end of a cantilever, with ON status when the metal contacts touch, and
- an OFF status when the two metal contacts do not touch.
A thermomechanical cantilever sensor switch (TCSS) configured with a first and second actuated electrical contact actuated independently to provide a SPST switch function, wherein the first contact is disposed-on, and electrically-connected with, a first bimorph within a first cantilever, and the second contact is disposed on and electrically-connected with a second bimorph within a second cantilever, wherein both cantilevers are suspended from a surrounding substrate;
- The bimorphs each comprise two fused legs, wherein each leg comprises a different thermal coefficient of expansion (TCE);
- the first bimorph of the first cantilever is thermally-connected to thermal absorbing structure.
- the electrical status ON and OF is defined by the actuated electrical contacts in touching and not touching positions, respectively;
- the electrical status ON or OFF is determined by the temperature differential between the two bimorphs;
- the first and second cantilevers comprise phononic MEMS structure disposed to provide thermal isolation between the respective bimorphs and the surrounding substrate;
- the thermal isolation provided by the phononic MEMS structure increases the thermal sensitivity for actuated movement of each electrical contact;
- the phononic MEMS structure comprises phononic crystal with elements disposed in an orderly format, and/or scattering elements disposed in a random format;
- the first and second electrical contacts are electrically connected through each respective first and second cantilevers to external contacting pads disposed on the surrounding platform.
- the switch status ON or OFF changes as the intensity of incident radiation heating the morph within the first cantilever reaches a specific level.
the two cantilevers are configured to provide a quiescent electrical status of the TCSS of normally-ON or normally-OFF.
The thermal absorbing structure is disposed within the bimorph, or thermally-connected to thermal absorbing structure disposed in close proximity to the bimorph, providing a sensitivity to incident radiation absorbed from an external photonic source;
Dependencies are inferred from the claim text.