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To realize high-precision rotation angle adjustment in micro-/nanomanipulation, a novel monolithic two-degrees-of-freedom (2-DOF) pure rotation platform is designed, fabricated, and tested in this article. The rotation platform is driven by two piezoelectric actuators. Rotation decoupling is realized based on three Hooke's joints, and a large rotation range is obtained based on two bridge-type mechanisms. Compared with other rotation platforms, the developed 2-DOF pure rotation platform has the advantages of fewer actuators due to rotation decoupling design and larger working frequency range due to compact structure and monolithic fabrication. An analytical model is established to calculate transmission ratio and input stiffness. The dominant parameters are determined based on sensitivity analysis. Finite-element analysis is conducted to investigate the characteristics of the rotation platform. Experimental tests are carried out to investigate the performance of the rotation platform. Decoupling test results show that the maximum rotation angles in the X- and Y-axis are 2.04 and 2.12 mrad, respectively, and the X- and Y-axis relative coupling errors are 2.03% and 2.09%, respectively. Closed-loop control results show that the settling time is 40 ms and the resolutions in both X- and Y-axis are 5 μrad. [ABSTRACT FROM AUTHOR]

We present a fast 3-D printing prototyping method for integrated antennas having internal features. Commercially available printers with soluble supports and airbrushing are utilized for fabrication and metal coating of antenna structures. This method includes modifications of the antenna geometry while preserving its integrity and performance. To get access to the interior of the design, windows are cut out of the antenna walls where the power flow shows local minima. These windows facilitate airbrushing the internal features of the antenna. As a proof of concept, we adopt a short-circuit variation of the Marchand balun whose attachment to the antenna wall facilitates its 3-D printing fabrication and rejects the common-mode resonance. The ground plane, balun, and dipole were monolithically fabricated in a single run. We then used copper deposition by airbrushing, which forms a sufficiently thick layer on the whole structure. The fabricated antenna shows a very good match to simulation results. A wideband resonance from 2.12 to 3.95 GHz is measured. The radiation pattern of the antenna remains stable across the frequency range with cross-polarization isolation higher than 30 dB. The measured gain of the antenna is 5.9 dB at 3 GHz. The fabrication techniques, discussed in this study, show promise for the future fabrication of 3-D printed integrated antennas with limited access to their interior features. [ABSTRACT FROM AUTHOR]

InGaAs/GaAs/AlGaAs multiple wavelength quantum well (QW) semiconductor laser diodes (LDs) have been fabricated by impurity-free vacancy disordering (IFVD) QW intermixing (QWI) method. The IFVD-QWI process was carried out by sputtering-depositing SiO2 mask layers on top of the complete InGaAs/GaAs/AlGaAs QW laser structure, emitting at 980 nm wavelength, and followed by a rapid thermal annealing at 880 °C for 60 s. The lasing wavelength of the devices fabricated from the intermixed wafer was blue-shifted with the increase of the mask layer thickness. The maximum emission wavelength blue shift of a processed as-cleaved laser reached 112 nm with the output-power more than 1000 mW. By using such an IFVD-QWI technique, multi-wavelength integrated LDs have also been successfully fabricated from a single chip.

Compared with conventional display technologies, liquid crystal display (LCD), and organic light emitting diode (OLED), micro-LED displays possess potential advantages such as high contrast, fast response, and relatively wide color gamut, low power consumption, and long lifetime. Therefore, micro-LED displays are deemed as a promising technology that could replace LCD and OLED at least in some applications. While the prospects are bright, there are still some technological challenges that have not yet been fully resolved in order to realize the high volume commercialization, which include efficient and reliable assembly of individual LED dies into addressable arrays, full-color schemes, defect and yield management, repair technology and cost control. In this article, we review the recent technological developments of micro-LEDs from various aspects. [ABSTRACT FROM AUTHOR]

Compared with conventional display technologies, liquid crystal display (LCD), and organic light emitting diode (OLED), micro-LED displays possess potential advantages such as high contrast, fast response, and relatively wide color gamut, low power consumption, and long lifetime. Therefore, micro-LED displays are deemed as a promising technology that could replace LCD and OLED at least in some applications. While the prospects are bright, there are still some technological challenges that have not yet been fully resolved in order to realize the high volume commercialization, which include efficient and reliable assembly of individual LED dies into addressable arrays, full-color schemes, defect and yield management, repair technology and cost control. In this article, we review the recent technological developments of micro-LEDs from various aspects.

This paper deals with the design of a monolithic tip-tilt-piston flexure manipulator for high-precision applications. The manipulator is first proposed with consideration of actuation isolation, which is a symmetrical and compact design and can be monolithically fabricated without using additive manufacturing. Kinematic and kinetostatic models are then analytically derived for quick parameter assessments. A case study is discussed finally, where a monolithic prototype has been made using CNC milling machining, comparisons among analytical, FEA and testing results are also undertaken. [ABSTRACT FROM AUTHOR]

The initial version of this paper was presented at 2014 Workshop on Fundamental Issues and Future Research Directions for Parallel Mechanisms and Manipulators, Tianjin, China.The conceptual design of three types of decoupled, compact, and monolithic XYZ compliant parallel manipulators (CPMs) is taken into account in this paper using the position space concept. The CPMs are termed CUBEs due to the shape of their compact structures. The position space of a compliant module is the combination of all permitted positions in an XYZ CPM system where the constraint of this compliant module in the XYZ CPM system remains unchanged when the position of the compliant module changes within the position space. The position of each compliant P joint is considered relative to its adjacent compliant joint/module rather than being considered in insolation. A design method for obtaining monolithic XYZ CPMs is proposed in terms of both the kinematic substitution and position spaces. Three types of monolithic XYZ CPMs are then demonstrated using the proposed method, with the help of three classes of kinematically decoupled three degrees of freedom translational parallel mechanisms. These monolithic XYZ CPMs include a 3-PPP (P: prismatic) XYZ CPM, a 3-PPPR (R: revolute) XYZ CPM, and a 3-PPPRR XYZ CPM. The position space concept can enable the system configurations to be designed based on the chosen optimization requirements, which include considerations such as compactness or minimization of parasitic rotations. This provides an efficient and systematic method to arrange the relative position between any two compliant joints/modules so that one can easily generate practical and useful configurations for XYZ CPMs. The resulting XYZ CPM is the most compact one when the fixed ends of the three actuated compliant P joints thereof overlap or are as close to each other as possible. [ABSTRACT FROM AUTHOR]

A novel retinal prosthetic device was developed using biocompatible liquid crystal polymer (LCP) to address the problems associated with conventional metal- and polymer-based devices: the hermetic metal package is bulky, heavy, and labor-intensive, whereas a thin, flexible, and MEMS-compatible polymer-based system is not durable enough for chronic implantation. Exploiting the advantageous properties of LCP such as a low moisture absorption rate, thermobonding, and thermoforming, we fabricate a small, light-weight, long-term reliable retinal prosthesis that can be conformally attached on the eye-surface. A LCP fabrication process using monolithic integration and conformal deformation was established enabling miniaturization and a batch manufacturing process as well as eliminating the need for feed-through technology. The functionality of the fabricated device was tested through wireless operation in saline solution. Its efficacy and implantation stability were verified through in vivo animal tests by measuring the cortical potential and monitoring implanted dummy devices for more than a year, respectively. [ABSTRACT FROM AUTHOR]

Owing to its low mechanical compliance, liquid metal is intrinsically suitable for stretchable electronics and future wearable devices. However, its invariable strain-resistance behavior according to the strain-induced geometrical deformation and the difficulty of circuit patterning limit the extensive use of liquid metal, especially for strain-insensitive wiring purposes. To overcome these limitations, herein, novel liquid-metal-based electrodes of fragmented eutectic gallium-indium alloy (EGaIn) and Ag nanowire (NW) backbone of which their entanglement is controlled by the laser-induced photothermal reaction to enable immediate and direct patterning of the stretchable electrode with spatially programmed strain-resistance characteristics are developed. The coexistence of fragmented EGaIn and AgNW backbone, that is, a biphasic metallic composite (BMC), primarily supports the uniform and durable formation of target layers on stretchable substrates. The laser-induced photothermal reaction not only promotes the adhesion between the BMC layer and substrates but also alters the structure of laser-irradiated BMC. By controlling the degree of entanglement between fragmented EGaIn and AgNW, the initial conductivity and local gauge factor are regulated and the electrode becomes effectively insensitive to applied strain. As the configuration developed in this study is compatible with both regimes of electrodes, it can open new routes for the rapid creation of complex stretchable circuitry through a single process., (© 2022 Wiley-VCH GmbH.)

We report on successful spectral phase encoding and decoding operation in a pair of monolithically integrated InP encoder chips, each consisting of an arrayed waveguide grating (AWG) pair and an eight-channel electrooptic phase shifter array. The monolithic fabrication process includes anisotropic reactive ion etching and planarizing hydride-vapor-phase-epitaxy lateral regrowth to realize buried hetero-waveguide structures in AWGs and phase shifters. Electrooptical modulation in the phase shifter arrays in the encoder chip achieved Walsh-code-based optical code-division multiple access (O-CDMA) encoding and decoding. The matched-code encoding-decoding operation resulted in error-free performance in the presence of an interferer, indicating good potential for O-CDMA network applications [ABSTRACT FROM PUBLISHER]

In this letter, the concept of driving tunable solid lens using microthermal actuator is presented. This microoptical device is composed of a flexible polydimethylsiloxane (PDMS) lens, silicon conducting ring, and silicon heater. The mismatching of coefficient of thermal expansion and stiffness between PDMS and silicon will lead to the deformation of polymer lens during heating, so as to further change its focal length. To demonstrate the feasibility of this approach, a microfabrication processes have been established to monolithically fabricate the present microoptical device. The typical experiment results show that the tunable focal length was up to 834 mum with an input current of 70 mA [ABSTRACT FROM PUBLISHER]

A new feedback scheme is used to achieve multiband unconditional stability in common source (CS) and common gate (CG) GaAs MESFET configurations. This technique extends the range of operation of both CG and CS beyond what is currently available. Results based on analytical formulations together with a description of the feedback design procedures are provided. Several CS and CG stabilized transistors were monolithically fabricated and tested [ABSTRACT FROM PUBLISHER]

In this letter, we report the fabrication of 2 × 2 crosspoint switches, which monolithically integrate passive waveguides, electro-absorption modulators and optical amplifiers onto one chip using sputtered SiO2 quantum-well intermixing technique. The switches have low insertion loss to be about 4-5 dB and extinction ratios up to 26 dB [ABSTRACT FROM PUBLISHER]