Microfluidic devices for photo-and spectroelectrochemical applications

The review presents recent developments in electrochemical devices for photo- and spectroelectrochemical investigations, with the emphasis on miniaturization (i.e., nanointerdigitated complementary metal-oxide-semiconductor devices, micro- and nano-porous silicon membranes or microoptoelectromechanical systems), silica glass/microreactors (i.e., plasmonic, Raman spectroscopy or optical microcavities) or polymer-based devices (i.e., 3D-printed, laser-engraved channels). Furthermore, we have evaluated inter alia the efficiency of various fabrication approaches for bioelectrochemical systems, biocatalysis, photochemical synthesis, or single nanoparticle spectroelectrochemistry. We envisioned the miniaturization of applied techniques such as cathodoluminescence, surface plasmon resonance, surface-enhanced Raman spectroscopy, voltametric and amperometric methods in the spectroelectrochemical microdevices. The research challenges and development perspectives of microfluidic, and spectroelectrochemical devices were also elaborated on.publishedVersio

Wafer level integration of epitaxial piezoelectric thin films for novel NEMS, MEMS and MOEMS applications

Pb(Zr, Ti)O3 (PZT) and (PhMg1/3Nb2/3O3)2/3-CPbTiO3)1/3 (PMN-PT) thin films are epitaxially deposited on 200 mm wafers using Solmates' Pulsed Laser Deposition (PLD) platform. Epitaxy is achieved using an optimized TiN template layer on the lattice mismatched silicon. SrTiO3 was used as buffer layer and LaNiO3 as oxide bottom electrode after which PZT and PMN-PT were deposited. A fully epitaxial thin film stack was confirmed by XRD analysis and the degree of epitaxy was found to be homogeneous across the wafer. The ferro- and piezoelectric properties were measured and found to be stable upon 103 switching cycles.publishedVersio

A Study of the Long-Term Electrochemical Stability of Thin-Film Titanium–Platinum Microelectrodes and Their Comparison to Classic, Wire-Based Platinum Microelectrodes in Selected Inorganic Electrolytes

This paper discusses the electrochemical properties of thin-film, planar, titanium–platinum (Ti-Pt) microelectrodes fabricated using glass or silicon substrates and compares their performance to the classic platinum (Pt) microelectrodes embedded in glass. To analyze the possible differences coming both from the size of the tested electrodes as well as from the substrate, short- and long-term electrochemical tests were performed on selected water electrolytes (KCl, HCl, KOH). To study the electrochemical response of the electrodes, the cyclic voltammetry (CV) measurements were carried out at different scanning rates (from 5 to 200 mV/s). Long-term tests were also conducted, including one thousand cycles with a 100 mV/s scan rate to investigate the stability of the tested electrodes. Before and after electrochemical measurements, the film morphology was analyzed using a scanning electron microscope (SEM). The good quality of the thin-film Pt electrodes and the high repeatability in electrochemical response have been shown. There are minor differences in standard deviation values taken from electrochemical measurements, comparing thin-film and wire-based electrodes. Damages or any changes on the electrodes’ surfaces were revealed by SEM observations after long-term electrochemical tests

On the effect of water-induced degradation of thin-film piezoelectric microelectromechanical systems

Lifetime and reliability in realistic operating conditions are important parameters for the application of thin-film piezoelectric microelectromechanical systems (piezoMEMS) based on lead zirconate titanate (PZT). Humidity can induce time-dependent dielectric breakdown at a higher rate compared to dry conditions, and significantly alter the dynamic behavior of piezoMEMS-devices. Here we assess the lifetime and reliability of PZT-based micromirrors with and without humidity barriers operated at 23°C in an ambient of 0 and 95 % relative humidity. The correlation of the dynamic response, as well as the ferroelectric, dielectric, and leakage properties, with degradation time was investigated. In humid conditions, the median timeto-failure was increased from 2.7×10 4 [1.9×10 4 -4.0×10 4 ] s to 1.1×10 6 [0.9×10 6 -1.5×10 6 ] s at 20 VAC continuous unipolar actuation, by using a 40 nm thick Al 2 O 3 humidity barrier. However, the initial maximum angular deflection, polarization, and dielectric permittivity decreased by about 6, 11, and 12 %, respectively, for Al 2 O 3 capped devices. For both bare and encapsulated devices, the onset of electrothermal breakdown-events was the dominant cause of degradation. Severe distortions in the device's dynamic behavior, together with failure from loss of angular deflection, preceded time-dependent dielectric breakdown in 95% relative humidity. Moreover, due to the film-substrate stress transfer sensitivity of thin-film devices, water-induced degradation affects the reliability of thin-film piezoMEMS differently than bulk piezoMEMS

A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy

Background: Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs

Microwave Characterization of Ba-Substituted PZT and ZnO Thin Films

The microwave dielectric properties of (Ba0.1Pb0.9)(Zr0.52Ti0.48)O3 (BPZT) and ZnO thin films with thicknesses below were investigated. No significant dielectric relaxation was observed for both BPZT and ZnO up to 30 GHz. The intrinsic dielectric constant of BPZT was as high as 980 at 30 GHz. The absence of strong dielectric dispersion and loss peaks in the studied frequency range can be linked to the small grain diameters in these ultrathin films.status: publishe

Refractive Index Sensing of Green Fluorescent Proteins in Living Cells Using Fluorescence Lifetime Imaging Microscopy

We show that fluorescence lifetime imaging microscopy (FLIM) of green fluorescent protein (GFP) molecules in cells can be used to report on the local refractive index of intracellular GFP. We expressed GFP fusion constructs of Rac2 and gp91phox, which are both subunits of the phagocyte NADPH oxidase enzyme, in human myeloid PLB-985 cells and showed by high-resolution confocal fluorescence microscopy that GFP-Rac2 and GFP-gp91phox are targeted to the cytosol and to membranes, respectively. Frequency-domain FLIM experiments on these PLB-985 cells resulted in average fluorescence lifetimes of 2.70 ns for cytosolic GFP-Rac2 and 2.31 ns for membrane-bound GFP-gp91phox. By comparing these lifetimes with a calibration curve obtained by measuring GFP lifetimes in PBS/glycerol mixtures of known refractive index, we found that the local refractive indices of cytosolic GFP-Rac2 and membrane-targeted GFP-gp91phox are ∼1.38 and ∼1.46, respectively, which is in good correspondence with reported values for the cytosol and plasma membrane measured by other techniques. The ability to measure the local refractive index of proteins in living cells by FLIM may be important in revealing intracellular spatial heterogeneities within organelles such as the plasma and phagosomal membrane

A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy

Abstract Background Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs. Methods Target (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility. Results Good agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits. Conclusion DIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician