A pressure sensor that combines two principles of measurement into one integrated unit with optical and electronic parts is fabricated and tested. The sensing element for both integrated parts is an embossed silicon diaphragm that deflects under differential pressure. The optical part of the sensor is based on Fabry-Perot interferometry; the electronic part of the sensor is based on the piezoresistive effect in silicon. In the application of Fabry-Perot interferometry, the sensing element utilizes an optical cavity, where interference of multiple reflections changes with movement of the diaphragm caused by pressure. In the application of the piezoresistive effect, a change in the electrical resistivity of a sensor material is induced by mechanical stress in the diaphragm and detected by a Wheatstone bridge circuit. The advantages of introducing the embossed diaphragm in sensor fabrication and its benefits for integration are discussed. The existence of a nearly ideal Fabry-Perot interferometer in the optical part of the sensor is demonstrated experimentally. Noise characteristics of the Fabry-Perot part of the sensor are presented. The independently produced electronic output serves to establish the quiescence point (Q-point) of the output from the optical part of the sensor.

Behavior consistent with Coulomb-mediated high-T$_C$ superconductivity is shown to be present in the intercalated group-4-metal nitride halides A$_x$(S)$_y$MNX, where the MNX host (M = Ti, Zr, Hf; X = Cl, Br) is partially intercalated with cations A$_x$ and optionally molecular species (S)$_y$ in the van der Waals gap between the halide X layers, expanding the basal-plane spacing d. The optimal transition temperature is modeled by T$_{C0}$ ${\propto}$ {\zeta}$^{-1}$({\sigma}/$A$)$^{1/2}$, where the participating fractional charge per area per formula unit {\sigma}/$A$ and the distance {\zeta}, given by the transverse A$_x$-X separation ({\zeta} < d), govern the interlayer Coulomb coupling. From experiment results for {\beta}-form compounds based on Zr and Hf, in which concentrations x of A$_x$ are varied, it is shown that {\sigma} = {\gamma}[v(x$_{opt}$ $-$ x$_0$)], where x$_{opt}$ is the optimal doping, x$_0$ is the onset of superconducting behavior, v is the A$_x$ charge state, and {\gamma} = 1/8 is a factor determined by the model. Observations of T$_C$ < T$_{C0}$ in the comparatively more disordered {\alpha}-A$_x$(S)$_y$TiNX compounds are modeled as pair-breaking by remote Coulomb scattering from the A$_x$ cations, which attenuates exponentially with increasing {\zeta}. The T$_{C0}$ values calculated for nine A$_x$(S)$_y$MNCl compounds, shown to be optimal, agree with the measured T$_C$ to within experimental error. The model for T$_{C0}$ is also found to be consistent with the absence of high-T$_C$ characteristics for A$_x$MNX compounds in which a spatially separated intercalation layer is not formed.