A CE-C4D Platform Integrating 3D-Printer Ecosystems, Luer-Standard Pneumatics, and Open-Source Hardware

Capillary electrophoresis with Capacitively Coupled Contactless Conductivity Detection (CE-C4D) offers high analytical efficiency and low sample consumption. However, commercial instrumentation remains cost-prohibitive for resource-limited or citizen science settings. Here, we report the design, fabrication, and experimental validation of a low-cost, modular CE-C4D platform based on open hardware architectures (dual C4D, Arduino, RAMPS, and syringe pump modules), FDM 3D-printed parts, 3D printer hardware, Luer-standard medical supplies for pneumatic integrity, and a commercial DC–DC converter. Pressure-driven flow tests demonstrated excellent pneumatic and hydrodynamic stability, yielding variation coefficients below 0.5% for displaced sample plugs. Low-pressure Dual-Opposite Injections of nanoliter-scale sample plugs were implemented using custom hollow-electrode manifolds and a motorized medical three-way valve. Operating under suppressed electroosmotic flow in 2.3 M acetic acid, simultaneous separation of inorganic ions (K+, Ca2+, Mg2+, NO3−, Cl−, SO42−) was achieved in synthetic and commercial hydroponic nutrient samples in less than 5 min for single-detector readings and 12 min for dual-point detection. Dual-point detection enables in-line auto-verification of assay validity, continuously confirming electromigration velocity, peak identity, and hydrodynamic consistency. The hardware achieves reliable run-to-run repeatability and robust fluidic control, providing an accessible, replicable instrument foundation for decentralized chemical profiling and quantitative analytical methods.