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3081 KiB

Open AccessArticle

A Rapid and Low-Cost Nonlithographic Method to Fabricate Biomedical Microdevices for Blood Flow Analysis

by Elmano Pinto, Vera Faustino, Raquel O. Rodrigues, Diana Pinho, Valdemar Garcia, João M. Miranda and Rui Lima

Micromachines 2015, 6(1), 121-135; https://doi.org/10.3390/mi6010121 - 30 Dec 2014

Cited by 51 | Viewed by 8540

Abstract

Microfluidic devices are electrical/mechanical systems that offer the ability to work with minimal sample volumes, short reactions times, and have the possibility to perform massive parallel operations. An important application of microfluidics is blood rheology in microdevices, which has played a key role [...] Read more.

Microfluidic devices are electrical/mechanical systems that offer the ability to work with minimal sample volumes, short reactions times, and have the possibility to perform massive parallel operations. An important application of microfluidics is blood rheology in microdevices, which has played a key role in recent developments of lab-on-chip devices for blood sampling and analysis. The most popular and traditional method to fabricate these types of devices is the polydimethylsiloxane (PDMS) soft lithography technique, which requires molds, usually produced by photolithography. Although the research results are extremely encouraging, the high costs and time involved in the production of molds by photolithography is currently slowing down the development cycle of these types of devices. Here we present a simple, rapid, and low-cost nonlithographic technique to create microfluidic systems for biomedical applications. The results demonstrate the ability of the proposed method to perform cell free layer (CFL) measurements and the formation of microbubbles in continuous blood flow. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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2747 KiB

Open AccessArticle

Sub-Micrometer Size Structure Fabrication Using a Conductive Polymer

by Junji Sone, Katsumi Yamada, Akihisa Asami and Jun Chen

Micromachines 2015, 6(1), 96-109; https://doi.org/10.3390/mi6010096 - 29 Dec 2014

Cited by 6 | Viewed by 5487

Abstract

Stereolithography that uses a femtosecond laser was employed as a method for multiphoton-sensitized polymerization. We studied the stereolithography method, which produces duplicate solid shapes corresponding to the trajectory of the laser focus point and can be used to build a three-dimensional (3D) structure [...] Read more.

Stereolithography that uses a femtosecond laser was employed as a method for multiphoton-sensitized polymerization. We studied the stereolithography method, which produces duplicate solid shapes corresponding to the trajectory of the laser focus point and can be used to build a three-dimensional (3D) structure using a conductive polymer. To achieve this, we first considered a suitable polymerization condition for line stereolithography. However, this introduced a problem of irregular polymerization. To overcome this, we constructed a support in the polymerized part using a protein material. This method can stabilize polymerization, but it is not suited for building 3D shapes. Therefore, we considered whether heat accumulation causes the irregular polymerization; consequently, the reduction method of the repetition rate of the femtosecond laser was used to reduce the heating process. This method enabled stabilization and building of a 3D shape using photo-polymerization of a conductive polymer. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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2164 KiB

Open AccessCommunication

Electrophoretic Deposition of Gallium with High Deposition Rate

by Hanfei Zhang, Yiping Feng, Sunand Santhanagopalan and Dennis Desheng Meng

Micromachines 2015, 6(1), 32-41; https://doi.org/10.3390/mi6010032 - 23 Dec 2014

Cited by 3 | Viewed by 6481

Abstract

In this work, electrophoretic deposition (EPD) is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher [...] Read more.

In this work, electrophoretic deposition (EPD) is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher than the typical value reported for electroplating, is obtained when employing a set of proper deposition parameters. The thickness of the film is shown to increase with deposition time when sequential deposition is employed. The concentration of Mg(NO₃)₂, the charging salt, is also found to be a critical factor to control the deposition rate. Various gallium micropatterns are obtained by masking the substrate during the process, demonstrating process compatibility with microfabrication. The reported novel approach can potentially be employed in a broad range of applications with Ga as a raw material, including microelectronics, photovoltaic cells, and flexible liquid metal microelectrodes. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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2391 KiB

Open AccessArticle

Miscible Organic Solvents Soak Bonding Method Use in a PMMA Multilayer Microfluidic Device

by He Zhang, Xiaowei Liu, Tian Li and Xiaowei Han

Micromachines 2014, 5(4), 1416-1428; https://doi.org/10.3390/mi5041416 - 10 Dec 2014

Cited by 19 | Viewed by 7219

Abstract

In this paper, we proposed a novel bonding technology to fabricate a microfluidic device based on Poly(methyl methacrylate) (PMMA). The method, which used chloroform and ethanol as miscible bonding solvent, can complete complex structures rapid assembly (10 min) at 40°C. A bonding strength [...] Read more.

In this paper, we proposed a novel bonding technology to fabricate a microfluidic device based on Poly(methyl methacrylate) (PMMA). The method, which used chloroform and ethanol as miscible bonding solvent, can complete complex structures rapid assembly (10 min) at 40°C. A bonding strength of 267.5 N/cm² can be achieved, while the micro channel deformation was less than 7.26%. Then we utilized this method to produce a three layers micro mixer, which included a T-shaped inlet channel and six H-shaped mixing units. Numerical simulation indicated that, the well mixing length of the mixer was only about 6 mm when Re = 10. Finally, fluorescence microscopy was used to verify mixer performance. The method provided the potential for mass production of multilayer rigid polymer microfluidic devices. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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3820 KiB

Open AccessArticle

Growth of Ultra-Long ZnO Microtubes Using a Modified Vapor-Solid Setup

by Zhihui Lu, Xin Heng, Anirban Chakraborty and Cheng Luo

Micromachines 2014, 5(4), 1069-1081; https://doi.org/10.3390/mi5041069 - 11 Nov 2014

Cited by 4 | Viewed by 6854

Abstract

In this work, we have modified the experimental setup for a vapor-solid (VS) process to synthesize Zinc oxide (ZnO) microtubes (MTs) with lengths up to 3 mm during a 90-min growth period. The critical idea behind this modification is to control the distribution [...] Read more.

In this work, we have modified the experimental setup for a vapor-solid (VS) process to synthesize Zinc oxide (ZnO) microtubes (MTs) with lengths up to 3 mm during a 90-min growth period. The critical idea behind this modification is to control the distribution of Zn vapor along the Si substrates. The morphology evolution of ZnO structures with the increasing reaction time was particularly explored. We found that, within the 90-min growth period, four different types of ZnO microstructures appeared in this synthesis process: microrods (MRs), short MTs, two-tier structures, and long MTs. Growth mechanisms were proposed to interpret the formation of these structures. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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2251 KiB

Open AccessArticle

Fabrication and Testing of an Osmotic Pressure Sensor for Glucose Sensing Application

by Nagesh Ch and Roy P. Paily

Micromachines 2014, 5(3), 722-737; https://doi.org/10.3390/mi5030722 - 18 Sep 2014

Cited by 9 | Viewed by 7658

Abstract

This paper presents a chemical reaction-free sensor, based on the osmosis principle, fabricated to measure the change in glucose concentration levels. The sensor consists of a square cavity filled with a known concentration of glucose solution and sealed with a semi-permeable membrane. The [...] Read more.

This paper presents a chemical reaction-free sensor, based on the osmosis principle, fabricated to measure the change in glucose concentration levels. The sensor consists of a square cavity filled with a known concentration of glucose solution and sealed with a semi-permeable membrane. The volume inside the cavity changes in proportion to the glucose concentration outside the device and introduces the displacement in the silicon (Si) membrane on the top. The main considerations targeted for this sensor are better response time, chemical-free nature, improved lifetime and absence of any mechanical excitations. Moreover, as the size of a system plays a major role, efforts have been taken to reduce the dimension of the presented system. The designed glucose sensor is fabricated by employing a bulk micromachining technology on a SOI (silicon on insulator) substrate. This will allow batch fabrication, as well as the integration of the electronic circuit on the same substrate. The output voltage obtained is varied from Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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2751 KiB

Open AccessArticle

Microfabrication of a Novel Ceramic Pressure Sensor with High Sensitivity Based on Low-Temperature Co-Fired Ceramic (LTCC) Technology

by Chen Li, Qiulin Tan, Wendong Zhang, Chenyang Xue, Yunzhi Li and Jijun Xiong

Micromachines 2014, 5(2), 396-407; https://doi.org/10.3390/mi5020396 - 24 Jun 2014

Cited by 11 | Viewed by 7812

Abstract

In this paper, a novel capacitance pressure sensor based on Low-Temperature Co-Fired Ceramic (LTCC) technology is proposed for pressure measurement. This approach differs from the traditional fabrication process for a LTCC pressure sensor because a 4J33 iron-nickel-cobalt alloy is applied to avoid the [...] Read more.

In this paper, a novel capacitance pressure sensor based on Low-Temperature Co-Fired Ceramic (LTCC) technology is proposed for pressure measurement. This approach differs from the traditional fabrication process for a LTCC pressure sensor because a 4J33 iron-nickel-cobalt alloy is applied to avoid the collapse of the cavity and to improve the performance of the sensor. Unlike the traditional LTCC sensor, the sensitive membrane of the proposed sensor is very flat, and the deformation of the sensitivity membrane is smaller. The proposed sensor also demonstrates a greater responsivity, which reaches as high as 13 kHz/kPa in range of 0–100 kPa. During experiments, the newly fabricated sensor, which is only about 6.5 cm², demonstrated very good performance: the repeatability error, hysteresis error, and nonlinearity of the sensor are about 4.25%, 2.13%, and 1.77%, respectively. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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1243 KiB

Open AccessArticle

An Experimental Investigation of Micro Pulsating Heat Pipes

by Kai-Shing Yang, Yu-Chi Cheng, Ming-Shan Jeng, Kuo-Hsiang Chien and Jin-Cherng Shyu

Micromachines 2014, 5(2), 385-395; https://doi.org/10.3390/mi5020385 - 20 Jun 2014

Cited by 24 | Viewed by 6538

Abstract

Two Si-based micro pulsating heat pipes (µPHPs) charged using HFE-7100 were either horizontally or vertically oriented and were tested using several heating powers. The width of each channel was 0.8 mm in one µPHP containing uniform channels, and the channel width was 1.0 [...] Read more.

Two Si-based micro pulsating heat pipes (µPHPs) charged using HFE-7100 were either horizontally or vertically oriented and were tested using several heating powers. The width of each channel was 0.8 mm in one µPHP containing uniform channels, and the channel width was 1.0 mm or 0.6 mm in the other µPHP, which did not contain uniform channels. The depth of each channel was 0.25 mm. The overall size of each µPHP was 60 × 10 × 1.25 mm. Visual observation and temperature measurement of the µPHPs under various conditions were performed and the results were analyzed. The results indicated that when the µPHPs were operated horizontally at a heating power ranging from 1 to 7 W, the pulsating two-phase flow in the channels of the µPHPs could not begin, except when the µPHP containing nonuniform channels was tested at a heating power of 7 W. With a heating power less than 5 W, the frequency of the sine-like oscillating displacement of the vapor slug increased and the displacement of the vapor slug reduced in either vertically oriented μPHP, as the heating power increased With a heating power higher than 5 W, periodic “start-stop” behaviors were observed in the vertical μPHP containing nonuniform channels. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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3105 KiB

Open AccessArticle

One-Step Combined-Nanolithography-and-Photolithography for a 2D Photonic Crystal TM Polarizer

by Kyung-Hak Choi, Jinwoo Huh, Yonghao Cui, Krutarth Trivedi, Walter Hu, Byeong-Kwon Ju and Jeong-Bong Lee

Micromachines 2014, 5(2), 228-238; https://doi.org/10.3390/mi5020228 - 29 Apr 2014

Cited by 6 | Viewed by 8734

Abstract

Photonic crystals have been widely investigated since they have great potential to manipulate the flow of light in an ultra-compact-scale and enable numerous innovative applications. 2D slab photonic crystals for the telecommunication C band at around 1550 nm have multi-scale structures that are [...] Read more.

Photonic crystals have been widely investigated since they have great potential to manipulate the flow of light in an ultra-compact-scale and enable numerous innovative applications. 2D slab photonic crystals for the telecommunication C band at around 1550 nm have multi-scale structures that are typically micron-scale waveguides and deep sub-micron-scale air hole arrays. Several steps of nanolithography and photolithography are usually used for the fabrication of multi-scale photonic crystals. In this work, we report a one-step lithography process to pattern both micron and deep sub-micron features simultaneously for the 2D slab photonic crystal using combined-nanoimprint-and-photolithography. As a demonstrator, a 2D silicon photonic crystal transverse magnetic (TM) polarizer was fabricated, and the operation was successfully demonstrated. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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Review

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5211 KiB

Open AccessReview

Fabrication of Micro/Nano Structures on Metals by Femtosecond Laser Micromachining

by K. M. Tanvir Ahmmed, Colin Grambow and Anne-Marie Kietzig

Micromachines 2014, 5(4), 1219-1253; https://doi.org/10.3390/mi5041219 - 20 Nov 2014

Cited by 336 | Viewed by 25130

Abstract

Femtosecond laser micromachining has emerged in recent years as a new technique for micro/nano structure fabrication because of its applicability to virtually all kinds of materials in an easy one-step process that is scalable. In the past, much research on femtosecond laser micromachining [...] Read more.

Femtosecond laser micromachining has emerged in recent years as a new technique for micro/nano structure fabrication because of its applicability to virtually all kinds of materials in an easy one-step process that is scalable. In the past, much research on femtosecond laser micromachining was carried out to understand the complex ablation mechanism, whereas recent works are mostly concerned with the fabrication of surface structures because of their numerous possible applications. The state-of-the-art knowledge on the fabrication of these structures on metals with direct femtosecond laser micromachining is reviewed in this article. The effect of various parameters, such as fluence, number of pulses, laser beam polarization, wavelength, incident angle, scan velocity, number of scans, and environment, on the formation of different structures is discussed in detail wherever possible. Furthermore, a guideline for surface structures optimization is provided. The authors’ experimental work on laser-inscribed regular pattern fabrication is presented to give a complete picture of micromachining processes. Finally, possible applications of laser-machined surface structures in different fields are briefly reviewed. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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