Iranian Journal of Manufacturing Engineering

Iranian Journal of Manufacturing Engineering

Design and fabrication of a microfluidic system based on chiral liquid crystal and CNC technology for sodium chloride detection

Document Type : Original Article

Authors
Seyed Mostafa Hosseinalipour 1
Milad Esfandiar 2
Hossein Rahimi Asiabaraki 2
Ali BashiriNezhad 1
1 Mechanical Engineering Department, Iran University of Science & Technology, Tehran, Iran
2 Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran
10.22034/ijme.2025.537359.2113
Abstract
This study investigates the application of chiral liquid crystals (CLCs) in microfluidic systems for precise detection of sodium chloride concentrations. Initially, an optical system based on 5CB liquid crystal was designed, consisting of a light source, polarizer, optical microscope, and color change recording equipment. Sodium chloride solutions with different concentrations were manually injected into the liquid crystal using a micropipette, and the color changes were recorded. Although this method was effective in detecting color variations, it faced limitations in portability and practical application due to manual injection and the need for additional optical components. To address these challenges, chiral liquid crystal (CLC) fabricated by mixing 5CB with BDH1305 chiral dopant replaced pure 5CB to enhance sensitivity to concentration changes and eliminate the need for external polarizers. Microfluidic chips were fabricated using a custom-built desktop CNC milling machine, which engraved microchannels with micron precision (200 μm width and 300 μm depth) on PMMA sheets. This device, with its advanced design and precise control, ensured uniform flow of solutions to the CLC reservoir. Recorded images were processed using ImageJ software, and RGB values were extracted for color change analysis. Results demonstrated that the microfluidic-CLC system, owing to the fabrication precision of the CNC device, recorded uniform and accurate color changes and measured sodium chloride concentrations with high accuracy. This innovative system, combining CNC technology and CLC sensing, provides an efficient tool for concentration measurement in medicine, food industry, and environmental sciences, with high potential for future development.
Keywords
Chiral Liquid Crystal
Microfluidic System
CNC Machine
Concentration Detection
Color Changes
RGB Analysis
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