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Register a new userNanoroughened plasmonic films for enhanced biosensing detection
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Although fluorescence is the prevailing labeling technique in biosensing applications, sensitivity improvement is still a striving challenge. We show that coating standard microscope slides with nanoroughened silver films provides a high fluorescence signal enhancement due to plasmonic interactions. As a proof of concept, we applied these films with tailored plasmonic properties to DNA microarrays. Using common optical scanning devices, we achieved signal amplifications by more than 40-fold.
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Fast, room temperature imaging at THz and sub-THz frequencies is an interesting feature which could unleash the full potential of plenty applications in security, healthcare and industrial production. In this Letter we introduce micromechanical bolometers based on silicon nitride trampoline membranes as broad-range detectors, down to the sub-THz frequencies. They show, at the largest wavelengths, room-temperature noise-equivalent-powers comparable to state-of-the-art commercial devices (~100 pW Hz-1/2); adding the good operation speed and the easy, large-scale fabrication process, the trampoline membrane could be the next candidate for cheap, room temperature THz imaging and related applications.
Conventional microscope objective lenses are diffraction limited, which means that they cannot resolve features smaller than half the illumination wavelength. Under white light illumination, such resolution limit is about 250-300 nm for an ordinary microscope. In this paper, we demonstrate a new superlensing objective lens which has a resolution of about 100 nm, offering at least two times resolution improvement over conventional objectives in resolution. This is achieved by integrating a conventional microscope objective lens with a superlensing microsphere lens using a 3D printed lens adaptor. The new objective lens was used for label-free super-resolution imaging of 100 nm-sized engineering and biological samples, including a Blu-ray disc sample, semiconductor chip and adenoviruses. Our work creates a solid base for developing a commercially-viable superlens prototype, which has potential to transform the field of optical microscopy and imaging.
A microstructured graphitic 4x4 multielectrode array was embedded in a single crystal diamond substrate (4x4 {uG-SCD MEA) for real-time monitoring of exocytotic events from cultured chromaffin cells and adrenal slices. The current approach relies on the development of a parallel ion beam lithographic technique, which assures the time effective fabrication of extended arrays with reproducible electrode dimensions. The reported device is suitable for performing amperometric and voltammetric recordings with high sensitivity and temporal resolution, by simultaneously acquiring data from 16 rectangularly shaped microelectrodes (20x3.5 um^2) separated by 200 um gaps. Taking advantage of the array geometry we addressed the following specific issues: i) detect both the spontaneous and KCl-evoked secretion simultaneously from several chromaffin cells directly cultured on the device surface, ii) resolve the waveform of different subsets of exocytotic events, iii) monitoring quantal secretory events from thin slices of the adrenal gland. The frequency of spontaneous release was low (0.12 Hz and 0.3 Hz respectively for adrenal slices and cultured cells) and increased up to 0.9 Hz after stimulation with 30 mM KCl in cultured cells. The spike amplitude as well as rise and decay time were comparable with those measured by carbon fiber microelectrodes and allowed to identify three different subsets of secretory events associated to full fusion events, kiss and-run and kiss-and-stay exocytosis, confirming that the device has adequate sensitivity and time resolution for real-time recordings. The device offers the significant advantage of shortening the time to collect data by allowing simultaneous recordings from cell populations either in primary cell cultures or in intact tissues.
A spectrometer for resonant inelastic X-ray scattering (RIXS) is proposed where imaging and dispersion actions in two orthogonal planes are combined to deliver full two-dimensional map of RIXS intensity in one shot with parallel detection in incoming hvin and outgoing hvout photon energies. Preliminary ray-tracing simulations with a typical undulator beamline demonstrate a resolving power well above 11000 in both hvin and hvout near a photon energy of 930 eV, with a vast potential for improvement. Combining such a spectrometer - nicknamed hv2 - with an XFEL source allows efficient time-resolved RIXS experiments.
We demonstrate niobium nitride based superconducting single-photon detectors sensitive in the spectral range 452 nm - 2300 nm. The system performance was tested in a real-life experiment with correlated photons generated by means of spontaneous parametric down conversion, where one of photon was in the visible range and the other was in the infrared range. We measured a signal to noise ratio as high as $4times 10^4$ in our detection setting. A photon detection efficiency as high as 64% at 1550 nm and 15% at 2300 nm was observed.
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