Pukyong National University

Pukyong National University Team Led by Professor Lim Do-Jin Develops the World’s First “General-Purpose Droplet Control Algorithm”

- Breakthrough solves long-standing challenges in CCEP-based digital microfluidics; published in <Sensors & Actuators B>

- Dramatically reduces control complexity, securing core technology for the ‘automation and miniaturization’ of CCEP systems

A research team led by Professor Lim Do-Jin of the Department of Chemical Engineering at Pukyong National University has developed the world’s first general-purpose droplet control algorithm for contact charge electrophoresis (CCEP)-based digital microfluidic systems.

The team’s achievement was published in <Sensors & Actuators: B. Chemical> (IF: 8.0), a globally recognized journal ranked within the top 2% of JCR in the field of Instruments & Instrumentation. The paper is titled ‘A local symmetric pattern-based actuation algorithm (L-SPAA) for contact charge electrophoresis-based digital microfluidic systems.’

The ‘L-SPAA’ developed by Professor Lim Do Jin’s team is the first generalized algorithm designed to control droplets in CCEP-based microfluidic systems.

Although conventional CCEP technology is an efficient method for transporting biomaterials by utilizing contact between electrodes and droplets, it has faced difficulties in commercialization due to the complexity of having to define separate electrode control rules for each droplet movement path.

To overcome these limitations, the research team established an innovative standardized framework in which all electrodes are arranged in alternating polarities and only a local symmetric pattern around the droplet (in a “ㅓㅏ”-shaped configuration) is manipulated. With this approach, droplets can be controlled freely regardless of movement direction or path using a single control rule. The method demonstrated overwhelming efficiency, reducing electrode control complexity by more than 70% and memory usage by more than 96% compared to existing technologies.

In addition, the research team introduced a new “priority-based control strategy” to address potential electrical interference issues that can arise when handling multiple droplets simultaneously. This approach assigns a control sequence to adjacent droplets, enabling them to be moved sequentially without collisions, and was shown to provide stable control even in complex multi-droplet scenarios.

In particular, using this strategy, the team successfully conducted experiments in which multiple cell spheroids (three-dimensional cell aggregates) were sequentially fused and the culture medium was exchanged, thereby opening the way for the automation of organoid(artificial organ) and assembloid cultivation―technologies essential for cancer research and new drug development.

Bae Seo-Jun, a postdoctoral researcher and first author of the study, said, “L-SPAA presents a clear standard for CCEP droplet control technology, which previously lacked well-defined guidelines.” He added, “Because precise control is now possible using only a small microcontroller without complex, high-end equipment, we expect this to become a core enabling technology that will accelerate the automation and miniaturization of CCEP systems.”

Professor Lim Do-Jin’s research team conducted this study with support from the National Research Foundation of Korea’s Mid-Career Researcher Support Program (RS-2021-NR058600). <Pukyong Today>