Miniature Configuration Research Articles

Miniature optical fiber curvature sensor via integration with GaN optoelectronics

Optical fiber curvature sensors have been considered as a promising option for human motion detection due to its good toughness, bending flexibility and anti-electromagnetic interference. However, for wearable devices, the miniature configuration is preferred, and a high integration of the light emitter, receiver and guided fiber is essential to configure the miniaturized sensing system. Here, we present a miniaturized curvature sensing system by integrating a GaN-based optoelectronic chip with the plastical optical fiber (POF). The light emitter and detector are fabricated on a GaN-on-sapphire wafer to form a tiny chip sized at 2.5 times 1.5 mm2. The on-chip photodetector (PD) effectively senses the reflected light intensity, extracting information on the fiber bending deformation. A compact curvature sensing system is demonstrated for finger motion detection with movement angles of 30–90° and frequencies of 0.4, 1, and 1.6 Hz. The results show that the monolithically integrated LED and PD chip can be combined with the POF with reliable operation. The demonstration of the monolithically integrated optoelectronic device suggests a promising potential technology for future wearable fiber optical sensor system.

SCALE STRUCTURE OF FRESHWATER CARP, CATLA CATLA (HAM-BUCH)

Numerous miniature configuration details, hidden on fish scale surface are of significance for fish identification, classification and taxonomy (Agassiz, 1834; Goodrich, 1908; Chu, 1935; Matsui, 1949; Kobayashi, 1951). The advent of techniques like Scanning Electron Microscopy (SEM) and utilization of its magnifying potencies for unfolding the architectural details of scale has been practiced by several eminent fish biologists to correlate this important aspect of scale morphology to fish taxonomy (DeLamater and Courtenay, 1972; DeLamater and Courtenay, 1973a, b, 1974; Lanzing and Higginbotham, 1974; DiCenzo and Sellers, 1998; Johal and Thomas, 2000; Ruiqing et al., 2000; Gao et al., 2001; Khemiri et al., 2001). The growing utilitarian aspect of the scale and its morphology thus makes it mandatory to elaborate the embedded morphoprints of scale to fit the relevant data better into the problem related to the field of fisheries. So realizing the significance of this aspect of scale structure, present study has been conducted to assess detailed scale structure of Catla catla using SEM technique.

Review on Electrolytic Conductivity Sensors

Electrolytic conductivity (EC) sensors are widely used in diverse industries, including: pharmaceuticals, food, power, manufacturing, and environmental monitoring. This article presents an overview and analysis of EC sensors used in these industries from the lowest to the highest range of conductivities and in applications, where there are strong requirements for accurate and traceable conductivity measurements of water and electrolyte solutions. Included are reported sensor designs based on two- and four-electrodes with parallel plates, coaxial cylinders, van der Pauw configurations, planar and miniature configurations, and contactless inductive or capacitive coupling. A comprehensive list of exact analytical formulas for computation of cell constants for the configurations is provided. The advantages and disadvantages of using frequency domain or time domain measurement schemes in these sensors are discussed, and the reader is guided to select the suitable method of sensor calibration among the methods available, computing uncertainty budgets, ensuring traceability to the International System of Units (SI) and compliance with standards, such as Pharmacopeias. Finally, trends in the development of EC sensors and the related challenges in relation to calibration and compliance with standards are presented. This article also introduces the reader to the EC cell of a sensor, which can be modeled by solving the Poisson-Nernst-Planck equations or using appropriate equivalent circuit diagrams. It is stepwise described how the models can be extended to include effects such as electrode polarization and steric effects of ions, and it is illustrated by means of an ideal EC cell, where guards eliminate fringe fields, that the simplest equivalent circuit with a single resistor and a single capacitor models electrolytic sensor data very well in the lower range of electrolytic conductivities.

Can low-temperature point discharge Be used as atomic emission source for sensitive determination of cyclic volatile methylsiloxanes?

Despite of increased interest in the application of miniature microplasma atomic spectrometry for environmental analytical chemistry, the amenable element detection range is limited to some metal elements and carbon due to it low power consumption. In this work, the generation of silicon atomic emission (251.6 nm and 288.2 nm) from the organosiloxanes was found possible in a low-temperature, low-power, and compact point discharge. Consequence, a tiny point discharge silicon optical emission spectrometer (μPD-OES) was exploited, and used as a novel GC detector for the determination of various cyclic volatile methyl siloxanes (cVMSs). Under the optimized conditions, the developed system provided limits of detection (LODs) of 0.2 mg L−1, 0.04 mg L−1, 0.03 mg L−1 and 0.02 mg L−1 of Si for hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane, respectively. Meanwhile, relative standard deviations (RSDs) of better than 2.3% were obtained. In contrast to gas chromatography mass spectrometer, GC-μPD-OES significantly simplifies the experimental setup with low power consumption and a miniature configuration. As far as we know, this work reports for the first time that silicon atomic emission can be generated in such low temperature microplasma. The accuracy of this system was validated by determining cVMSs in five daily-used shampoo samples collected from retail store, providing satisfactory recoveries (84%–114%) and excellent agreement with values determined by GC-MS at the 95% confidence level.

Photochemical deposition fabricated highly sensitive localized surface plasmon resonance based optical fiber sensor

Though the localized surface plasmon resonance (LSPR) based optical fiber sensors have high sensitivity and miniature configurations, most of them suffer from complicated operations and expensive cost in fabrications. To overcome the shortcomings, here we propose a low-cost and simple photochemical method for preparing fiber LSPR sensors by depositing silver nanoparticles on the fiber end face from the reaction solution containing silver nitrate as a metal salt and sodium citrate as a reducing agent. The measurements of sucrose solutions indicate that the proposed sensor can reach the high sensitivity up to ∼400 nm/RIU with satisfied repeatability and reusability. Considering its simple fabrication, high sensitivity and good repeatability, it is believed the proposed sensor can be widely used in various applications such as rapid detection and in-field measurement.

Instabilities and Bifurcations of a DFB Laser Frequency-Stabilized by a High-Finesse Resonator

Recently reported miniature configurations with semiconductor distributed feedback lasers under resonant feedback are considered theoretically. Limiting instabilities and bifurcations are systematically explored by combining the theory of chirp reduction and a bifurcation analysis. It is shown that the regime of optimal chirp reduction also exhibits the best local stability. It suffers only from undamping of relaxation oscillations in a finite interval of feedback strength. The existence of a separate strong-feedback regime with high stability is consistent with the two experiments available so far. We regard this feature as a generic specificum of miniature configurations not known from large-scale setups. This regime can open new prospects for applications of compact frequency-stabilized semiconductor lasers with extremely low noise and small line width.

Continuous wave dual-wavelength Nd:YVO4 laser working at 1064 and 1066 nm

We demonstrate a continuous-wave (CW) dual-wavelength Nd:YVO4 laser working at 1064 and 1066 nm simultaneously. The method of Nd:YVO4 crystal angle tuning is used to balance the ratio of the stimulated emission cross sections of the two wavelengths, leading to the realization of a simultaneous dual-wavelength operation from only one laser. The experimental results show that at a 2.85 W pump power, the maximum output powers at wavelengths of 1064 and 1066 nm are 0.55 and 0.54 W, respectively. The linear resonate cavity is as short as 10 mm, which gives the laser the advantages of a miniature configuration and low threshold. Such a dual-wavelength laser can be very attractive for the development of compact THz sources based on difference frequency generation.

Design of CPW-Fed Circularly Polarized Slot Antenna With a Miniature Configuration

This letter proposes the design of a new miniaturized circularly polarized (CP) printed square slot antenna (PSSA) fed by a coplanar waveguide (CPW). The characteristics of the design are that the CP operation and impedance matching can be independently achieved. The 3-dB axial-ratio band can be excited by protruding into the slot a halberd-shaped metal strip from the signal line of the CPW, whereas the VSWR ≤ 2 impedance band can be produced by implanting in the slot a grounded asymmetric inverted-T strip. Design rules established for the proposed antenna can effectively reduce the sizes of the ground plane and the slot.

Research on Entirely-integrated Spatial-bending Shape Memory Alloy Actuator

A new structure of Entirely-integrated Spatial-bending Shape Memory Alloy Actuators (ESSMAA) is first presented. Three SMA wires, which are trained to remember "U" recovery shape, are embedded in liquid silicone rubber to be solidified upon room temperature, companied with displacement sensors and connective wires. The Spatial bending, which is accomplished through heating SMA wires by suitable current, can restore flexibly as soon as stopping heating. Thus, the compact, two-way, mechanical and electrical incorporation actuator is completed. Be provided with the merits such as high load-weight ratio, low energy dissipation and direct driving, the actuators can realize miniature configuration, simple drive and control, precise operation and flexible movement pose synthetically. On the basis of expounding the operation principle in detail, the curvature sensor, which is composed of six stain gauges, makes displacement control precise. After analyzing equilibrium of forces and moments, the numeric calculation equations are deduced. Subsequently, the approximate arithmetic making use of superpose principle is researched in contrast with numeric arithmetic. The manufacture of the prototype is discussed in details and the precise displacement control is implemented also. Finally, the experiments of the actuator proof fine qualities of the operation performances.

COMBUSTION OF A SOLID FUEL TUBE WITH CONTAINED LIQUID OXIDIZER IN A HOT GAS ATMOSPHERE

This work investigates the combustion behavior of a miniature configuration, which combines a solid fuel and a liquid oxidizer. A small diameter (about 1 mm) solid fuel tube is filled with a liquid oxidizer and embedded in a solid propellant strand. Two specific cases are studied experimentally: an aluminum tube filled with hydrogen peroxide and a polyethylene tube filled with nitric acid. During combustion, the regressing propellant surface exposes the aluminum/polyethylene tube, and provides the necessary thermal conditions for the establishment of a local miniature flamelet, resulting from oxidizer emerging from the inner core of the tube and fuel supplied by the tube wall. High speed video pictures reveal the details of the local diffusion flamelet expanding from the embedded tube. A qualitative miniature flamelet model is suggested, based on physical considerations and resembling, in the micro scale, solid oxidizer/solid fuel combustion. Thermochemical calculations show that an optimal combination of a polymeric fuel (e.g., HTPB), aluminum and a liquid oxidizer, can theoretically increase the heat of combustion by 10–20%, implying a potential enhancement of the specific impulse by about 6% to 12% over conventional solid propellants.

A miniature ultransonic pump using a bending disk transducer and a gap

It is known that if a pipe end is faced at a vibrating surface in liquid with a small gap, liquid is suctioned into the pipe. As a miniature configuration, we introduce a bending disk transducer 30 mm in diameter using a ring-shaped PZT element. The disk vibrator is worked at the fundamental resonance frequency of 19 kHz of the bending mode. To optimize the pipe geometry, we experimentally investigated the effect of the outer diameter on the pump performance. As a result, the outer/inner diameter ratio of 3:2 is optimum for the gap smaller than 20 μm. We achieved the maximum pump pressure of 14.8 kPa and the maximum flow rate of 10 ml/min. using the prototype pump.

A new miniature mechanical testing procedure: Application to intermetallics

A new miniature double-shear testing procedure is introduced for the testing of semibrittle materials such as intermetallics. Detailed experiments on samples of pure Al and an Al-5 pct Mg solid solution alloy confirm that the miniature configuration provides consistent and reliable results when using either a circular or a square cross section. In addition, it is demonstrated that the data obtained using miniature specimens are consistent with results from conventional large double-shear specimens and from specimens tested under tensile conditions. The miniature testing technique is used to provide preliminary mechanical data on a Ni-45 pct Al-5 pct Fe intermetallic.