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