Simple Miniaturization Research Articles

The Current State of Optical Sensors in Medical Wearables.

Optical sensors play an increasingly important role in the development of medical diagnostic devices. They can be very widely used to measure the physiology of the human body. Optical methods include PPG, radiation, biochemical, and optical fiber sensors. Optical sensors offer excellent metrological properties, immunity to electromagnetic interference, electrical safety, simple miniaturization, the ability to capture volumes of nanometers, and non-invasive examination. In addition, they are cheap and resistant to water and corrosion. The use of optical sensors can bring better methods of continuous diagnostics in the comfort of the home and the development of telemedicine in the 21st century. This article offers a large overview of optical wearable methods and their modern use with an insight into the future years of technology in this field.

Advanced bioactive nanomaterials for biomedical applications.

Bioactive materials are a kind of materials with unique bioactivities, which can change the cellular behaviors and elicit biological responses from living tissues. Bioactive materials came into the spotlight in the late 1960s when the researchers found that the materials such as bioglass could react with surrounding bone tissue for bone regeneration. In the following decades, advances in nanotechnology brought the new development opportunities to bioactive nanomaterials. Bioactive nanomaterials are not a simple miniaturization of macroscopic materials. They exhibit unique bioactivities due to their nanoscale size effect, high specific surface area, and precise nanostructure, which can significantly influence the interactions with biological systems. Nowadays, bioactive nanomaterials have represented an important and exciting area of research. Current and future applications ensure that bioactive nanomaterials have a high academic and clinical importance. This review summaries the recent advances in the field of bioactive nanomaterials, and evaluate the influence factors of bioactivities. Then, a range of bioactive nanomaterials and their potential biomedical applications are discussed. Furthermore, the limitations, challenges, and future opportunities of bioactive nanomaterials are also discussed.

A multi-frequency circularly polarized metasurface antenna array based on quarter-mode substrate integrated waveguide for sub-6 applications

A miniaturized multi-frequency circularly polarized array is designed in this paper. The antenna array is composed of three independent sub-arrays employing modified quarter-mode substrate ntegrated aveguide (QMSIW) to achieve three circularly polarized frequency bands. By introducing strip-slot, the impedance bandwidth of the antenna array is broadened while the dimension is decreased by 75% to realize miniaturization. Meanwhile, metasurface causes the impedance bandwidth of the sub-array to be further enhanced. Moreover, the metal vias are employed in the antenna array design to further achieve miniaturization. The antenna array is manufactured and measured to verify the design. Both the measured and simulated results display that the array achieves the impedance bandwidths of 10%, 11.7%, and 14.8% and axial ratio bandwidths of 8.8%, 8.0%, and 8.5% at 2.5, 3.5, and 4.8 GHz, respectively. The gain is stable in the operating band within an uncertainty of 0.7 dBi. The whole dimension is 0.92λ × 0.63λ × 0.04λ, where λ 0 is the wavelength at the lowest resonant frequency. Furthermore, the simple structure and miniaturization provides great convenience in sub-6 applications.

Ag nanoparticles outperform Au nanoparticles for the use as label in electrochemical point-of-care sensors

Electrochemical immunosensors enable rapid analyte quantification in small sample volumes, and have been demonstrated to provide high sensitivity and selectivity, simple miniaturization, and easy sensor production strategies. As a point-of-care (POC) format, user-friendliness is equally important and most often not combinable with high sensitivity. As such, we demonstrate here that a sequence of metal oxidation and reduction, followed by stripping via differential pulse voltammetry (DPV), provides lowest limits of detection within a 2-min automatic measurement. In exchanging gold nanoparticles (AuNPs), which dominate in the development of POC sensors, with silver nanoparticles (AgNPs), not only better sensitivity was obtained, but more importantly, the assay protocol could be simplified to match POC requirements. Specifically, we studied both nanoparticles as reporter labels in a sandwich immunoassay with the blood protein biomarker NT-proBNP. For both kinds of nanoparticles, the dose-response curves easily covered the ng∙mL−1 range. The mean standard deviation of all measurements of 17% (n ≥ 4) and a limit of detection of 26 ng∙mL−1 were achieved using AuNPs, but their detection requires addition of HCl, which is impossible in a POC format. In contrast, since AgNPs are electrochemically less stable, they enabled a simplified assay protocol and provided even lower LODs of 4.0 ng∙mL−1 in buffer and 4.7 ng∙mL−1 in human serum while maintaining the same or even better assay reliability, storage stability, and easy antibody immobilization protocols. Thus, in direct comparison, AgNPs clearly outperform AuNPs in desirable POC electrochemical assays and should gain much more attention in the future development of such biosensors.

Development of an On-Chip Antibiotic Permeability Assay With Single Molecule Detection Capability.

Electrophysiology is the method of choice to characterize membrane channels. In this paper, we demonstrate a patch pipette based simple miniaturization that allows performing conductance measurements on a planar lipid bilayer in a microfluidic channel. Membrane proteins were reconstituted into Giant Unilamellar Vesicles (GUVs) by electroswelling, and GUVs with a single channel insertion were patched at the tip of pipette. We applied this approach to investigate the interactions of porins from E.coli with single antibiotics, and this will potentially provide information on the permeability rates. The results of this paper suggest that this approach can be extended to the integration of several pipettes into the microfluidic channel from different positions, allowing the multiplexed recordings and also reducing the substrate consumption below volumes.

Distortion Correction for the Gun Barrel Bore Panoramic Image

Single Reflector Panoramic Imaging System (SRPIS) has been widely used because of its advantages such as simple structure, fast imaging, integration and miniaturization. It can observe objects around the reflector mirror, which fits for the quality inspection of gun barrel bore. However, its images often suffer from serious distortions in radial and tangential directions. Therefore, to ensure the accuracy of captured images, distortion must be eliminated. In this paper, a distortion correction method is proposed based on the imaging characteristics of SRPIS. Firstly the relationship between the height of a certain point on the gun barrel bore and the radius of image point is derived. Then the correction model is built based on the relationship. Aiming at the captured annular image, a new chessboard corner detection algorithm is proposed. The correction parameters are obtained by using the algorithm according to the labeled image. The real experiment results demonstrate that the correction effects of radial and tangential distortions are satisfactory. The error is controlled at sub-pixel level.

2D and 3D cell microarrays in pharmacology

To analyze the phenotypic consequences of perturbing mammalian cells with drugs, there is an increasing need for systematic cell-based assays in an HTS format. Cell microarrays provide an attractive solution as they offer more than a simple miniaturization and mechanization of conventional microtiter plates. While standard monolayer two-dimensional culture conditions are poor mimics of the cellular environment in situ, microfabricated systems enable three-dimensional organotypic cell cultures and have the potential to provide biological insight not achievable before. This article compares different cell microarray formats and evaluates their potential use in the drug discovery process.

Cover Picture: A Simple Miniaturization Protocol to Produce Multicomponent Micro‐ and Nanostructures (Small 7/2006)

The cover picture illustrates a new method of nanolithography, stepwise contraction and adsorption nanolithography (SCAN), that should in principle be able to extend the advantages of multicomponent microfabrication into smaller dimensions, as well as to reach the spatial precision afforded by scanning probe lithography. The left column depicts the balloon analogy of SCAN, in which the writing “small” on the balloon is miniaturized upon deflation. The right column presents a laser confocal micrograph of a two‐component array (red and green fluorescent dyes) generated after one and five SCAN cycles (top and bottom, respectively) in 2D reduction. Scale bars are 500 and 50 μm, respectively. For more information, please read the Communication “A Simple Miniaturization Protocol to Produce Multicomponent Micro‐ and Nanostructures” by G.‐y. Liu and co‐workers on page 884 ff.