Micromachines

14 pages, 11137 KB

Open AccessArticle

Ultra-Precision Turning of Ferrous and Non-Ferrous Material by Sapphire Tool

by Chung Chi Chiu, Yintian Xing, Wai Sze Yip and Suet To

Micromachines 2026, 17(6), 641; https://doi.org/10.3390/mi17060641 - 22 May 2026

Ultra-precision machining of ferrous alloys remains challenging because conventional diamond tools suffer severe thermochemical wear, whereas ultrasonic vibration-assisted cutting requires complex and costly equipment. This study investigates single-crystal sapphire as an alternative cutting-tool material for ultra-precision machining of both non-ferrous and ferrous metals. [...] Read more.

Ultra-precision machining of ferrous alloys remains challenging because conventional diamond tools suffer severe thermochemical wear, whereas ultrasonic vibration-assisted cutting requires complex and costly equipment. This study investigates single-crystal sapphire as an alternative cutting-tool material for ultra-precision machining of both non-ferrous and ferrous metals. A sapphire tool was fabricated from a polished wafer, laser-shaped into an equilateral triangular insert, vacuum-brazed onto a tungsten carbide carrier, and finished by ultra-fine grinding to yield a well-defined cutting edge. Ultra-precision turning experiments were conducted on copper and 420 stainless steel using a Moore Nanotech 350FG lathe, and the performance of the sapphire tool was benchmarked against conventional diamond (copper) and cubic boron nitride (CBN) tools (stainless steel) under comparable cutting conditions. Surface roughness (Ra) and topography were characterized using an optical surface profiler, while scanning electron microscopy and atomic force microscopy were employed to assess tool wear and cutting-edge geometry. The sapphire tool produced mirror-like surfaces with average surface roughness (Ra) values of 6.4 nm on copper and 39.1 nm on 420 stainless steel, compared with 1.3 nm for diamond on copper and 92.9 nm for CBN on stainless steel. Across both materials, sapphire generated regular, stable tool marks and exhibited minimal wear, with no catastrophic edge degradation or clear evidence of severe chemical interaction with the steel workpiece. These results demonstrate that sapphire is a viable tool material for extending diamond turning-level surface quality to stainless steel without ultrasonic assistance. Full article

(This article belongs to the Section D：Materials and Processing)

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24 pages, 25588 KB

Open AccessArticle

Development of a Bionic Bistable Compliant Mechanism for the LDI Machine

by Ruizhou Wang, Junhong Li and Hua Wang

Micromachines 2026, 17(6), 640; https://doi.org/10.3390/mi17060640 - 22 May 2026

Abstract

Rigid mechanisms (RMs) are widely adopted in the vision-based measurement (VBM) system of laser direct imaging (LDI) machines. Constant-stiffness compliant mechanisms (CMs) improve the performance of traditional RMs. Unfortunately, constant-stiffness CMs still exhibit high energy consumption and limited adaptability during fast focusing. Inspired [...] Read more.

Rigid mechanisms (RMs) are widely adopted in the vision-based measurement (VBM) system of laser direct imaging (LDI) machines. Constant-stiffness compliant mechanisms (CMs) improve the performance of traditional RMs. Unfortunately, constant-stiffness CMs still exhibit high energy consumption and limited adaptability during fast focusing. Inspired by the hierarchical structure and mechanical behavior of ligaments and tendons, this paper proposes a bionic bistable compliant mechanism (BBCM) to replace constant-stiffness CMs. The BBCM exhibits dynamic stiffness characteristics throughout the focusing stroke, with low stiffness in the transition phase to reduce energy consumption during rapid focusing and high local stiffness near the stable positions to maintain focusing stability. A numerical model is established to analyze the variable-stiffness and bistable characteristics of the proposed BBCM. Prototype tests demonstrate the bistable response, dynamic feasibility, and energy-saving potential of the mechanism. Under the tested camera-loaded flying-shot condition, compared with the constant-stiffness CM, the BBCM reduces electrical and mechanical energy consumption by 12.37% and 9.74%, respectively. The target recognition results indicate that the BBCM-based system maintains comparable visual measurement performance. These results demonstrate that the proposed BBCM provides a feasible mechanism-level solution for energy-efficient dual-position focusing in LDI machines. Full article

(This article belongs to the Special Issue Emerging Technologies and Applications for Semiconductor Industry)

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9 pages, 2912 KB

Open AccessArticle

Symmetric Surface Acoustic Wave Tweezers Based on 128° YX-LN for Dynamic Manipulation of Particle Patterns

by Peng Zhang and Hongliang Wang

Micromachines 2026, 17(6), 639; https://doi.org/10.3390/mi17060639 - 22 May 2026

Abstract

In the fields of cell engineering, bio-fabrication, and targeted therapy, achieving high-precision manipulation of microparticles and cells remains a technical challenge. Although acoustic tweezers based on surface acoustic waves (SAWs) offer a promising solution, the structural complexity of conventional SAW devices has limited [...] Read more.

In the fields of cell engineering, bio-fabrication, and targeted therapy, achieving high-precision manipulation of microparticles and cells remains a technical challenge. Although acoustic tweezers based on surface acoustic waves (SAWs) offer a promising solution, the structural complexity of conventional SAW devices has limited their practical applications. This work proposes a symmetric interdigitated transducer (IDT)-based acoustic tweezers device featuring a simple structure and high flexibility for modulating acoustic pressure field patterns and enabling particle manipulation. Theoretical investigations into the particle manipulation mechanism of the proposed device were conducted using the finite element method. A detachable polymethyl methacrylate (PMMA) assembly chamber was also designed. The effectiveness of the device was validated through dynamic and reconfigurable manipulation experiments using fluorescent polystyrene microspheres. Experimental results demonstrate that the proposed device can rapidly and precisely modulate SAW to achieve array-based manipulation of particle clusters, forming corresponding array patterns. Compared with conventional sorting methods, this device offers advantages including low cost, high precision, ease of operation, and good biocompatibility, making it suitable for large-scale manipulation of microparticles and biological cells. This technology has the potential to expand the application landscape of SAW and may emerge as a cutting-edge approach for directed cell assembly and culture. Full article

(This article belongs to the Section B：Biology and Biomedicine)

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4 pages, 156 KB

Open AccessEditorial

Editorial for the Special Issue on SiC Based Miniaturized Devices, 3rd Edition

by Stephen E. Saddow, Brenda L. VanMil and Benoit Hamelin

Micromachines 2026, 17(6), 638; https://doi.org/10.3390/mi17060638 - 22 May 2026

Abstract

Silicon Carbide: Enabling Next-Generation Power Electronics and High-Performance Computing [...] Full article

(This article belongs to the Special Issue SiC Based Miniaturized Devices, 3rd Edition)

11 pages, 4614 KB

Open AccessArticle

A High-Efficiency Dual-Polarized Transmitarray Antenna with Flat Gain Performance

by Xin-Hui Jiao, Li Zhang and Yu Zhang

Micromachines 2026, 17(6), 637; https://doi.org/10.3390/mi17060637 - 22 May 2026

Abstract

This article presents a high-efficiency dual-polarized transmitarray antenna which achieves flat gain characteristics. First, a wideband triple-layer subwavelength element is designed, achieving high transmission amplitude and a full 360° transmission phase range at 10 GHz. To enhance the passband, an isolated element and [...] Read more.

This article presents a high-efficiency dual-polarized transmitarray antenna which achieves flat gain characteristics. First, a wideband triple-layer subwavelength element is designed, achieving high transmission amplitude and a full 360° transmission phase range at 10 GHz. To enhance the passband, an isolated element and a cross-shaped middle layer are incorporated. Additionally, four vias connect the top and bottom layers to induce the current resonance, extending the phase range to 360° and improving the radiation efficiency. Based on the element, a transmitarray prototype with 185 elements is fabricated and measured, showing a gain of 27.1 dBi at the center frequency 10.2 GHz, with a radiation efficiency of 58.9%, and a 0.5 dB gain bandwidth of 12.7%. Within the 1 dB gain bandwidth, a minimum radiation efficiency of 37% is achieved at 11.4 GHz. Full article

(This article belongs to the Section E：Engineering and Technology)

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1 pages, 136 KB

Open AccessRetraction

RETRACTED: Jiang et al. Measuring Liquid Droplet Size in Two-Phase Nozzle Flow Employing Numerical and Experimental Analyses. Micromachines 2022, 13, 684

by Lin Jiang, Wei Rao, Lei Deng, Atilla Incecik, Grzegorz Królczyk and Zhixiong Li

Micromachines 2026, 17(6), 636; https://doi.org/10.3390/mi17060636 - 22 May 2026

Abstract

The journal retracts the article titled “Measuring Liquid Droplet Size in Two-Phase Nozzle Flow Employing Numerical and Experimental Analyses” [...] Full article

27 pages, 2427 KB

Open AccessReview

Modern Potentiostat Architectures for Electrochemical Sensing: Design, Integration, and Future Directions

by Reagan Aviha and Gymama Slaughter

Micromachines 2026, 17(6), 635; https://doi.org/10.3390/mi17060635 - 22 May 2026

Abstract

Potentiostats are essential to electrochemical sensing, enabling precise control of electrode potentials and measurement of current responses. As demand grows for portable, wearable, and point-of-care systems, potentiostat design has evolved from benchtop instruments to compact, low-power, and wirelessly connected platforms. This review provides [...] Read more.

Potentiostats are essential to electrochemical sensing, enabling precise control of electrode potentials and measurement of current responses. As demand grows for portable, wearable, and point-of-care systems, potentiostat design has evolved from benchtop instruments to compact, low-power, and wirelessly connected platforms. This review provides a comprehensive, system-level perspective on modern potentiostat architectures, covering operational principles, analog front-end design, signal generation and acquisition, communication protocols, and software integration. Unlike prior reviews that treat these aspects independently, this work integrates electrochemical theory with electronic design and data communication frameworks. Key components, including operational amplifiers, transimpedance amplifiers, DAC/ADC subsystems, and microcontroller-based control, are examined alongside communication protocols such as SPI, I²C, Bluetooth Low Energy, Wi-Fi, and NFC. Critical challenges related to miniaturization, noise, power constraints, and reproducibility are analyzed using representative platforms. This review highlights the transition of potentiostats into integrated, intelligent, and connected sensing systems, and outlines design considerations for scalable electrochemical applications in clinical, environmental, and industrial domains. Full article

(This article belongs to the Special Issue Point-of-Care Testing Based on Biosensors and Biomimetic Sensors)

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Micromachines, Volume 17, Issue 6 (June 2026) – 7 articles

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