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In this paper we present the results of a systematic study on the magnetic field penetration depth of superconducting niobium thin films. The films of thicknesses ranging from 8 to 300 nm were deposited on a Si substrate by dc magnetron sputtering. The values of the penetration depth ͑0͒ were obtained from the measurements of the effective microwave surface impedance by employing a sapphire resonator technique. Additionally, for the films of thickness smaller than 20 nm, the absolute values of ͑0͒ were determined by a microwave transmission method. We found that the reduction of the film thickness below 50 nm leads to a significant increase of the magnetic field penetration depth from about 80 nm for 300 nm thick film up to 230 nm for a 8 nm thick film. The dependence of the penetration depth on film thickness is described well by taking into account the experimental dependences of the critical temperature and residual resistivity on the thickness of the niobium films. Structural disordering of the films and suppression of superconductivity due to the proximity effect are considered as mechanisms responsible for the increase of the penetration depth in ultrathin films.

In NSTEMI patients, an immediate invasive approach does not offer an advantage over an early or a selective invasive approach with respect to large myocardial infarctions as defined by peak CK-MB levels, which is supported by similar clinical outcomes. ClinicalTrials.gov NCT00402675.

The dependence of the effective surface impedance Zeff=Reff+iXeff of superconducting thin films on the film thickness d, on the magnetic field penetration depth λ, and on the dielectric properties of the substrate material is investigated theoretically by means of impedance transformations. It was found that the effective surface resistance Reff can be expressed by RSf(d/λ)+Rtrans where RS is the intrinsic surface resistance of the superconductor. The function f(d/λ) describes the altered current density distribution in the film. Rtrans arises from power transmission through the film. It depends on d and λ as well as on the dielectric properties of the substrate material and is significantly altered in the case of a resonant background. The effective surface reactance Xeff of a superconducting thin film can be expressed by XS cosh(d/λ) where XS=ωμ0λ is the intrinsic surface reactance. Measurements of Zeff at 87 GHz have been performed for YBa2Cu3O7−δ thin films grown epitaxially by laser ablation on SrTiO3, MgO, and LaAlO3. With the best films, Reff (77 K) values of 21 mΩ and RS (77 K) values of 8 mΩ were achieved. The temperature dependence of λ was found to be in good agreement to both weak-coupling BCS theory in the clean limit and the empirical two-fluid model relation with λ (0 K) values ranging from 140 to 170 nm and 205 to 250 nm, respectively.

A graphene field-effect transistor (gFET) was non-covalently functionalised with 1-pyrenebutyric acid N-hydroxysuccinimide ester and conjugated with anti-CD63 antibodies for the label-free detection of exosomes. Using a microfluidic channel, part of a graphene film was exposed to solution. The change in electrical properties of the exposed graphene created an additional minimum alongside the original Dirac point in the drain-source current (Ids) - back-gate voltage (Vg) curve. When phosphate buffered saline (PBS) was present in the channel, the additional minimum was present at a Vg lower than the original Dirac point and shifted with time when exosomes were introduced into the channel. This shift of the minimum from the PBS reference point reached saturation after 30 minutes and was observed for multiple exosome concentrations. Upon conjugation with an isotype control, sensor response to the highest concentration of exosomes was negligible in comparison to that with anti-CD63 antibody, indicating that the functionalised gFET can specifically detect exosomes at least down to 0.1 μg/mL and is sensitive to concentration. Such a gFET biosensor has not been used before for exosome sensing and could be an effective tool for the liquid-biopsy detection of exosomes as biomarkers for early-stage identification of diseases such as cancer.

Currently the world is being challenged by a public health emergency caused by the coronavirus pandemic (COVID-19). Extensive efforts in testing for coronavirus infection, combined with isolating infected cases and quarantining those in contact, have proven successful in bringing the epidemic under control. Rapid and facile screening of this disease is in high demand. This review summarises recent advances in strategies reported by international researchers and engineers concerning how to tackle COVID-19 via rapid testing, mainly through nucleic acid- and antibody- testing. The roles of biosensors as powerful analytical tools are emphasized for the detection of viral RNAs, surface antigens, whole viral particles, antibodies and other potential biomarkers in human specimen. We critically review in depth newly developed biosensing methods especially for in-field and point-of-care detection of SARS-CoV-2. Additionally, this review describes possible future strategies for virus rapid detection. It helps researchers working on novel sensor technologies to tailor their technologies in a way to address the challenge for effective detection of COVID-19.

Spoof plasmon surfaces consisting of linear arrays of subwavelength grooves are proposed as a novel platform for THz sensing. The tightly confined spoof plasmons, coupled via an Otto prism setup, are sensitive to the refractive index of the dielectric filling the grooves. Phase jumps at spoof plasmon resonances are used as a readout response for refractive index sensing. An overall sensitivity of 0.49 THz RIU−1 with figures‐of‐merit as high as 49 are achieved.

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