A portable and affordable aligner for the assembly of microfluidic devices

This is an aligner for the assembly of multilayer microfluidic devices. It has three main parts:
1. A base that contains the stages for alignment control and illumination (Fig. 1A). The entire aligning device is supported by the base aluminum piece (see Table 1) on which the Z-stage jack is screwed. Then on the top of the Z-stage, a stage adaptor is attached which contains a LED lamp for illumination. The X/Y/θ stage is screwed on the top of the stage adaptor and can support the PDMS layer during the aligning process.
2. The holding arm that fixes one of the substrates. This piece is screwed on the top of the holder support (Fig. 1A and 2). The holding arm has a cavity (substrate niche shown in detail in Fig. 2C) where the substrate is placed and fixed using two aluminum sheets and four 2.5 mm shortened Allen screws.
3. The digital microscope for visualization and its plastic holder. The microscope is connected to the Raspberry Pi chip that can be attached to the back of the device. Microscope visualization is performed through a smartphone connected to the Raspberry Pi.
The aligner presented in this work is characterized by its small size and was designed for the assembly of microfluidic devices in small laboratories.

The remarkable aspects of the aligner can be described as:
● The aligner allows the assembly of microfluidic devices from two or more layers. These layers can be constituted by different substrates. During the alignment, the substrate in the holder is kept still whereas the other is moved with the precision stages to achieve alignment between both layers.
● The small size of the aligner makes it portable and easy to set in small laboratories. It can be stored in a drawer and carried without disassembling it.
● Microscopic visualization of the alignment process is done on a smartphone that connects to the digital microscope through the Raspberry Pi. This aspect makes unnecessary the use of computers or monitors for the function of the device.
● The substrate holder can be easily interchangeable for the assembly of different substrates and materials.
● The alignment error of the aligner is around 20 µm which makes it adequate for the fabrication of many kinds of microfluidic devices

*Please note that the original files for the Raspberry Pi case (.stl files), were obtained from: https://www.thingiverse.com/thing:3349103/files

本装置为一款用于多层微流控器件组装的对准器，主要包含三大组成部分：
1. 基座：集成对准控制与照明模块（图1A）。整套对准装置由铝合金基座支撑（详见表1），Z轴升降台通过螺纹固定于该基座之上。Z轴升降台顶部搭载载台转接件，转接件内置用于照明的LED灯。X/Y/θ轴载台通过螺纹固定于载台转接件顶部，可在对准过程中支撑聚二甲基硅氧烷（PDMS）层。
2. 夹持臂：用于固定其中一块基板。该部件通过螺纹固定于支架支撑座顶部（见图1A与图2）。夹持臂设有空腔（基板卡槽，细节见图2C），基板放置于此空腔内，并通过两片铝板与四颗2.5mm短内六角螺钉固定。
3. 可视化用数码显微镜及其塑料支架：显微镜与树莓派（Raspberry Pi）芯片相连，该芯片可安装于装置背部。显微镜的可视化效果可通过连接至树莓派的智能手机实现。

本研究提出的这款对准器以小巧紧凑为显著特点，专为小型实验室的微流控器件组装场景设计。

该对准器的突出特性如下：
● 可实现两层及以上微流控器件的组装，各层可采用不同基板材料。对准过程中，夹持臂内的基板保持静止，另一基板则通过高精度载台移动，以完成两层间的对准。
● 装置体积小巧，具备便携性，易于在小型实验室中搭建部署，可直接收纳于抽屉中，且无需拆解即可携带。
● 对准过程的显微可视化可通过连接至树莓派的智能手机完成，无需额外使用计算机或显示器即可实现装置的正常运行。
● 基板夹持器可便捷更换，以适配不同基板与材料的组装需求。
● 该对准器的对准误差约为20μm，可满足绝大多数微流控器件的制备需求。

*请注意：本装置配套的树莓派外壳（.stl格式文件）源自以下链接：https://www.thingiverse.com/thing:3349103/files