Herein we report the fabrication of an advanced sensor for the detection of hydrogen sulfide (H S) at room temperature, using thin films of rare-earth metal (RE)-based metal-organic framework (MOF) with underlying fcu topology. This unique MOF-based sensor is made via the in situ growth of fumarate-based fcu-MOF (fum-fcu-MOF) thin film on a capacitive interdigitated electrode. The sensor showed a remarkable detection sensitivity for H S at concentrations down to 100 ppb, with the lower detection limit around 5 ppb. The fum-fcu-MOF sensor exhibits a highly desirable detection selectivity towards H S vs. CH , NO , H , and C H as well as an outstanding H S sensing stability as compared to other reported MOFs.

This work reports on the fabrication of an advanced capacitive sensor based on a MFM-300 (In) MOF for the detection of SO2 at room temperature. The sensor revealed remarkable SO2 sensitivity down to 75 ppb with excellent stability and selectivity to other common gases/vapors.

This work reports on the fabrication and deployment of a select metal-organic framework (MOF) thin film as an advanced chemical capacitive sensor for the sensing/detection of ammonia (NH) at room temperature. Namely, the MOF thin film sensing layer consists of a rare-earth (RE) MOF (RE-fcu-MOF) deposited on a capacitive interdigitated electrode (IDE). Purposely, the chemically stable naphthalene-based RE-fcu-MOF (NDC-Y-fcu-MOF) was elected and prepared/arranged as a thin film on a prefunctionalized capacitive IDE via the solvothermal growth method. Unlike earlier realizations, the fabricated MOF-based sensor showed a notable detection sensitivity for NH at concentrations down to 1 ppm, with a detection limit appraised to be around 100 ppb (at room temperature) even in the presence of humidity and/or CO. Distinctly, the NDC-Y-fcu-MOF based sensor exhibited the required stability to NH, in contrast to other reported MOFs, and a remarkable detection selectivity toward NH vs CH, NO, H, and CH. The NDC-Y-fcu-MOF based sensor exhibited excellent performance for sensing ammonia for simulated breathing system in the presence of the mixture of carbon dioxide and/or humidity (water vapor), with no major alteration in the detection signal.

A magnetic nanocomposite has been implemented as artificial hair on a giant magnetoimpedance (GMI) thin-film sensor for flow sensing. The 500 μm long and 100 μm in diameter pillars are composed of iron nanowires incorporated in polydimethylsiloxane (PDMS). The nanowires' length and diameter are 6 μm and 35 nm, respectively. Upon fluid flow, the pillars are deflected, causing a change in the magnetic field at the GMI element and a corresponding change in impedance. The permanent magnetic behavior of the nanowires in combination with the GMI sensor and the high elasticity of the PDMS pillars result in a high-performance flow sensor with low power consumption and potential for remote detection. No additional magnetic field is required to magnetize the nanowires or bias the sensor, which simplifies miniaturization and integration in microsystems. At a power consumption of 31.6 μW, air flow rates up to 190 mm s(-1) can be detected with a sensitivity of 24 mΩ (mm)(-1) s and a resolution of 0.56 mm s(-1) while the range for water flow is up to 7.8 mm s(-1) with a sensitivity of 0.9 Ω (mm)(-1) s and a resolution of 15 μm s(-1). When power consumption is reduced to as low as 80 nW a high resolution of 32 μm s(-1) is still maintained.

Synthesis of CNT-HKUST-1 composite thin films.  Investigation of morphological, crystalline, and Raman-scattering characteristics of composite thin films.  Coating of HKUST-1 and CNT-HKUST-1 thin films on QCM.  Optimization of CNT-HKUST-1 composite ratio for enhanced humidity detection.