Miniature Volume Research Articles

A modified Prussian blue biosensor with improved stability based on the use of self-assembled monolayers and polydopamine for quantitative L-glutamate detection.

Aminiature L-glutamate (L-Glu)biosensor is describedbased on Prussian blue (PB) modification with improved stability by using self-assembled monolayers (SAMs) technology and polydopamine (PDA). A gold microelectrode (AuME) was immersed in NH2(CH2)6SH-ethanol solution, forming well-defined SAMs via thiol-gold bonding chemistry which increased the number of deposited Prussian blue nanoparticles (PBNPs) and confined them tightly on the AuME surface. Then, dopamine solution was dropped onto the PBNPs surface and self-polymerized into PDA to protect the PB structure from destruction. The PDA/PB/SAMs/AuME showed improved stability through CV measurements in comparison with PB/AuME, PB/SAMs/AuME, and PDA/PB/AuME. The constructed biosensor achieved a high sensitivity of 70.683 nAµM-1cm-2 in the concentrationrange 1-476µM L-Gluwith a low LOD of 0.329µM and performed well in terms of selectivity, reproducibility, and stability. In addition, the developed biosensor was successfully applied to the determination of L-Glu in tomato juice, and the results were in good agreement with that of high-performance liquid chromatography (HPLC). Due to its excellent sensitivity, improved stability, and miniature volume, the developed biosensor not only has a promising potential for application in food sample analysis but also provides a good candidate for monitoring L-Glu level in food production.

Microhole fiber-optic sensors for nanoliter liquid measurement

• This paper review the research status of microhole fiber based nanoliter liquid sensors. • This paper illustrates the microhole fiber based nanoliter liquid sensors for several variables measurement. • The microhole fiber gives a new possibility for nanoliter liquid measurement. • The future development directions of microhole fiber-optic sensors for nanoliter liquid are discussed. This article reviews the development of nanoliter liquid sensors based on microhole fiber. To measure liquid characteristics in microscale is crucial in the field of environmental pollution monitoring, food and drug safety testing, life science research, clinical application, chemical analysis and biomedical research. Microhole optical fiber with micro air holes can provide fitting space and circulation channel for the measurement of miniature volume liquid. Microhole optical fiber sensors have the characteristics of simple structure, enclosed environment, strong light and liquid interaction, which can meet the requirements of multi-parameter, high sensitivity and pollution-free measurement of minimal specimen. Here, we outline the cumulative introduction and the previous experimental research work on microhole fiber-optic sensors for nanoliter liquid, and ends with some conclusions and prospects. We hope this review can provide rigorous and organized literature to researchers/students for the basic understanding, trends, and practical utility of microhole fiber sensors.

An all-fiber optical attenuator based on adjustable coupling angle of microfiber

A tunable all-fiber optical attenuator (AOA) based on microfiber with adjustable coupling angle is reported and demonstrated. The AOA is fabricated of a microfiber probe coupled to a tapered fiber on the waist region through van der Waals and electrostatic forces. The attenuation can be tuned by adjusting the coupling angle of the two microfibers. When the coupling is fabricated of angles adjust from 80o to 10o, the optical attenuation can be tuned in a large range from 5.7 dB to 40.1 dB with low insertion loss. The simulation and experimental show that the coupling length can be changed by increasing the coupling angle, which results in decreasing the attenuation of AOA. The attenuation of AOA is decreased linearly by increasing the coupling angle. It provides a feasible approach to achieve attenuators with miniature volume, low cost, and multiple functions in optical communication and fiber lasers.

Deviations in yield and ultimate tensile strength estimation with the Small Punch Test: Numerical analysis of pre-straining and Bauschinger effect influence

There is a growing interest on the Small Punch Test (SPT) and its many applications in a broad range of industries and sectors. The miniature volume of the SPT specimen eases the mechanical characterization of components and structures when standard tests are impracticable. But this miniature test is limited for one of its more constraining requirements: the material isotropy. Since this test subjects the material to triaxial stress and strain fields, isotropy is necessary to compare the resulted data from SPT with the standard tests, which generally show uniaxial stress fields. Another key element of this question is that initially, isotropic material can lose this property due to a cold pre-straining process and the existence of the Bauschinger effect. In this investigation, a numerical study with the finite element method was performed to understand the influence of pre-straining and the Bauschinger effect in yield strength and ultimate tensile strength estimation with the SPT. This study concludes that in the absence of isotropy, generated by a pre-straining, the SPT estimated a mean value of the principal yield strength components of the yield surface. It is also verified that presence of pre-straining in the SPT specimens invalidated their use to calculate the coefficients of the correlation equations for yield strength estimation.

High-Resolution Implantable Microcoil Antennas for Blood-Vessel Imaging in High-Field MRIs

This article presents rectangular and circular intravascular receive-only (Rx) open interior microcoils (MCs) for blood-vessel and brain-aneurysm imaging with two different magnetic resonance imaging (MRI) frequencies (128 and 298 MHz for field strengths 3 and 7 T, respectively). The proposed Rx MCs have a miniature volume of 4.92 mm3. They offer a wider bandwidth, homogenous radio frequency (RF) receptivity, a high signal-to-noise ratio, and better vessel imaging than that offered by state-of-the-art MCs. In addition, they have open interiors that enable uninterrupted blood flow during MRI scanning and reduce motion artifacts. The proposed MCs were used to mimic different blood vessels of the brain, heart, neck, and kidneys in a realistic human voxel-based Duke model. We compared the reception efficiency ( $R_{x,eff}$ ) and the sum of $B_{1}^{-}$ strengths (i.e., $\Sigma B_{1}^{-}$ ) in the region of interest (ROI) for the combined approach involving the birdcage (BC)/surface coil and the MC for various coil arrangements. The proposed MCs were fabricated and integrated with the 3-D-printed blood-vessel model. The simulation results indicate that the proposed MCs achieved the improvements of 72% and 75% in $\Sigma B_{1}^{-}$ and $R_{x,eff}$ , respectively, in the selected ROI (the blood vessel). Moreover, the MR images obtained by the proposed MCs exhibited high sensitivity of the blood signal and offered selective imaging of the arterial walls. According to the results, the proposed Rx MCs can be applied to perform intravascular imaging of smaller blood vessels.

Simulated Operational Path Analysis Method for the Separation of Intake and Exhaust Noises

The classical transfer path analysis (TPA) method has become a standard measurement method. It has high accuracy but remains a time-consuming and complex measurement, which limits its application in industry. The operational transfer path analysis (OTPA) method is known for its high efficiency; however, the accuracy of this method for industrial application is controversial. To separate the intake and exhaust noises in the vehicle, this study presents a novel TPA method called simulated operational path analysis (SOPA). The transmissibility from the reference point to the target response point is estimated by using an external noise source to simulate the intake and exhaust noises under operating condition. In addition, the improved dual-microphone noise reduction technology is used to eliminate the background noise in the reference response. The method is validated by an experimental bench. The result shows that its high accuracy can be compared with the classical TPA method. Because there is no need to use a special miniature volume source to estimate the passive subsystem frequency response functions and identify the operational source loads, the efficiency of the SOPA method is higher than the classic TPA method and is close to the OTPA method.

A Double-Branch Surface Detection System for Armatures in Vibration Motors with Miniature Volume Based on ResNet-101 and FPN.

In this paper, a complete system based on computer vision and deep learning is proposed for surface inspection of the armatures in a vibration motor with miniature volume. A device for imaging and positioning was designed in order to obtain the images of the surface of the armatures. The images obtained by the device were divided into a training set and a test set. With continuous experimental exploration and improvement, the most efficient deep-network model was designed. The results show that the model leads to high accuracy on both the training set and the test set. In addition, we proposed a training method to make the network designed by us perform better. To guarantee the quality of the motor, a double-branch discrimination mechanism was also proposed. In order to verify the reliability of the system, experimental verification was conducted on the production line, and a satisfactory discrimination performance was reached. The results indicate that the proposed detection system for the armatures based on computer vision and deep learning is stable and reliable for armature production lines.

Multi-aperture stereo reconstruction for artificial compound eye with cross image belief propagation.

The artificial compound eye is a new type of camera that has miniature volume and large field of view (FOV), while the captured image is an array of sub-images, and each sub-image captures a part of the full FOV. To obtain a complete image with a full FOV, reconstruction is needed. Due to the parallax between adjacent sub-images, the reconstruction of images is depth related. In this paper, to address the image reconstruction of a specific artificial compound eye-eCley-a cross image belief propagation method is proposed to estimate the depth map. Since the small size and small FOV of the sub-image lead to little contextual information for pairwise matching, the information of neighboring sub-images is integrated into the belief propagation step to propagate the message across images. Therefore, the belief propagation step is able to gather as much information as needed from all the sub-images to obtain an accurate depth result. As a consequence, a stereo image with the full FOV and corresponding depth map can be obtained based on the estimated depth of sub-images. Experimental results on real data show the effectiveness of the proposed method.

Threshold Values Analysis of Substrate Parameters Based on MEMS Microstrip Filter

High frequency filters are important components in microwave facilities application. With miniature volume, high performance and integratability, MEMS microstrip filter can significantly improve performance of Radio frequency system. By calculating chebyshev coupled microstrip bandpass filter design scheme, Threshold values of MEMS microstrip substrate parameters are defined to analyze dimensions variation property of MEMS microstrip filter relates with substrate parameters. Selection principle of substrate parameters for MEMS microstrip filter is presented, which indicates thickness and relative dielectric constant of substrate should not exceed the threshold values. The principle of threshold values can be applied as a guide on research and application of MEMS microstrip filter.

An innovative miniature microbial fuel cell fabricated using photolithography

Recently microbial fuel cells (MFCs) have attracted increasing interests in both environmental and energy fields. Among the various MFC configurations, miniature microbial fuel cell (mini-MFC) has a great potential for the application in medical, communication and other areas because of its miniature volume and high output power density. In this work, a 25-μL single-chamber mini-MFC was fabricated using the photolithography technique. The plate-shaped gold anodic electrode in the mini-MFC showed a higher electrochemical activity than the stripe-shaped one. A biofilm of Shewanella oneidensis MR-1 was formed on the surface of gold electrode in this micro-liter-scale MFCs. As a result, a maximum power density of 29mW/m2 and a maximum current density of 2148mA/m2 were achieved by this single-chamber mini-MFC.

MC1 Micro‐Power Consuming Broadband Digital Seismograph

AbstractA new generation of digital seismic data acquisition device—MC1 Micro‐Power Cosuming and Broad‐Band Digital Seismograph was designed and built in our Lab. Its power dissipation is less than 300mW. It has some merits including miniature volume, light mass and low costs. It is an ideal device for the acquisition of high‐resolution natural seismic data, as well as for the fields of seismic sounding and engineering seismology.

Evaluation of Miniature and High-Volume Bioassays for Screening Insecticides

Three methods for screening insecticides and acaricides were evaluated against select arthropod targets: tobacco budworm, Heliothis virescens (F.), beet armyworm, Spodoptera exigua (Hubner), Colorado potato beetle, Leptinotarsa decemlineata (Say), and the twospotted spider mite, Tetranychus urticae Koch. Methods varied in amounts of test solutions delivered and included a moderate pressure rotating spray tower that sprayed 50 ml of solution to runoff on 3 plant species, and 2 miniature volume assays; a low pressure, airbrush applicator that delivered 1 ml to both surfaces of individual leaves; and an agar-based artificial diet assay (Lepidoptera only) that delivered small aliquots (50 μl) of test solutions to the surface of the diet. Bioassays were compared using 2 avermectin insecticides, abamectin and emamectin benzoate, 2 pyrethroid insecticides, fenvalerate and lambda-cyhalothrin, 2 organophosphorous insecticides, mevinphos and trichlorfon, and 1 ecdysone agonist, tebufenozide. All 3 methods were comparable at estimating the sensitivity of arthropods to these compounds. Differences in lethal concentration values among assays were species specific. Variation among assays was more apparent with less potent compounds (e.g., organophosphorous compounds and tebufenozide) compared with more potent compounds (pyrethroids and avermectins) for H. virescens , whereas in S. exigua and T. urticae , lethal concentration values were comparable among bioassay types for most compounds tested. These data indicate that low volume bioassays were comparable to high volume bioassays at detecting and estimating insecticidal activity against a select panel of arthropod pests. The potential of miniature volume bioassays for use in insecticide discovery programs is discussed, with particular reference to screening programs that rely on sample collections that are available in limited quantities, such as natural product and combinatorial chemistry sources.