Physics in Medicine最新文献

For the fabrication of dental inlays and crowns precise information on patients' teeth morphology is required. Besides the conventional method, where mold materials impressions are prepared, the use of digital scanners is more and more becoming a central part in the nowadays dentistry. The aim of the manuscript is to compare the accuracy of master models based on two intra-oral digital scanners and silicone impressions. A metal cast reference arch model with predefined measurement points was scanned using the Lava™ Chairside Oral Scanner C.O.S. and the iTero™ Intraoral Scanner respectively. These scans were applied for the fabrication of models using rapid prototyping and milling from a proprietary resin. In addition, plaster models were produced using conventional A-silicone impressions. Using a coordinate measuring machine and a micro computed tomography scanner the models were evaluated with micrometer precision. The mean distance deviations from model to model correspond to 112 μm (C.O.S.), 50 μm (iTero™) and 16 μm (gypsum). The results verified the high precision of the conventional technique based on A-silicone impressions and plaster models. The accuracy of the master models obtained on the basis of the digital scans is clinically sufficient to fabricate bridges with up to four units.

The light-addressable potentiometric sensor (LAPS) has the unique feature to address different regions of a sensor surface without the need of complex structures. Measurements at different locations on the sensor surface can be performed in a common analyte solution, which distinctly simplifies the fluidic set-up. However, the measurement in a single analyte chamber prevents the application of different drugs or different concentrations of a drug to each measurement spot at the same time as in the case of multi-reservoir-based set-ups. In this work, the authors designed a LAPS-based set-up for cell culture screening that utilises magnetic beads loaded with the endotoxin (lipopolysaccharides, LPS), to generate a spatially distributed gradient of analyte concentration. Different external magnetic fields can be adjusted to move the magnetic beads loaded with a specific drug within the measurement cell. By recording the metabolic activities of a cell layer cultured on top of the LAPS surface, this work shows the possibility to apply different concentrations of a sample along the LAPS measurement spots within a common analyte solution.

Advanced neuroprostheses need high density, mechanically flexible contacts with superior electrophysiological performance. Carbon nanotubes have shown interweaving with neurites are well suited but are opposed by ongoing nanoparticle biocompatibility discussions. We present a route circumventing those issues by immersing multiwalled carbon nanotubes (MWCNT) in silicone rubber and re-etch the surface yielding a MWCNT-lawn electrically contacted towards the percolative bulk. The use of tetra-n-butylammonium fluoride (TBAF) and sodium hydroxide solution (NaOH) leads to desired freestanding CNT strands still covered by residual rubber of approximately 13 nm thickness. The biocompatibility of such interfaces has been proven by WST-1-Assays for cell metabolism of 3T3NIH fibroblasts and SH-SY5Y neuroblastoma cells in terms of growth and morphology. Neural cell adhesion is proven with biomolecular markers. The electrical performance reaches percolation conductivities of up to 1.6 × 10² S/m. The lowest impedance was 1.3 × 10² Ωcm² at 1 kHz, which is similar to gold reference electrodes whilst their capacitive roll off is lowered in electrophysiological arrangements. When compared to pure MWCNTs the performance is decreased due to the insulating residual rubber encasement. However, this is seen to be a reasonable loss in the light of the increased biosafety of rubber shielded MWCNT neural interfaces.