Syringe pump-embedded, on-demand sample supply and collection system for droplet 3D cell culture in digital microfluidics

A syringe pump-embedded electromagnetic dispensing and suction (EMDS) system was developed for 3D cell culture in digital microfluidics to overcome the challenges of conventional dispensing technologies. The entire process of droplet 3D cell culture, from cell suspension droplet seeding to culture medium exchange, collection and analysis, has been successfully demonstrated in the EMDS system without the use of additional equipment, demonstrating its potential as a dispensing system for droplet 3D cell culture in microfluidic systems. To integrate sample loading, dispensing, splitting, and collection functions into a single EMDS system, the bi-directional operation of dispensing and suction was implemented using a single solenoid actuator and oil-mediated indirect liquid handling. The system introduces samples via a pipette or chamber insertion, eliminating the hassle of using a syringe such as a syringe filling and providing convenient loading of samples without dead volume issues, even for small sample volumes. Each component of the EMDS system is designed in a modular way and can be assembled in a block assembly type, so it can be configured and replaced easily and flexibly, showing high usability. We hope that with such a high degree of design freedom, the proposed EMDS system can be applied not only to dispensing systems for digital microfluidics but also to microchannels in the near future.