Digital microfluidics (DMF) is a transformative fluid handling technology based on the precise manipulation of very low-volume (typically nanoliter-scale droplets) liquid samples. DMF-based technology enables increased automation and precision of common laboratory liquid handling operations such as dispensing, transfer, storage and analysis by utilizing miniaturized substrates or chips. DMF can be used to enhance or automate analytical techniques such as NGS library preparation, immunoassays, MS, NMR spectroscopy, chemical synthesis, and separation and extraction procedures.
Analogous to digital microelectronics, digital microfluidic functions can be combined and reused within hierarchical design structures to execute complex procedures, such as chemical synthesis or bioassays, built up in step-by-step sequences. Furthermore, in contrast to traditional continuous-flow microfluidics, digital microfluidics works much the same way as traditional benchtop protocols, only with much smaller volumes and much greater automation. This enables a wide range of established chemical procedures and protocols that can be seamlessly transferred to a nanoliter droplet DMF configuration. Several advantages are associated with DMF platforms including low-volume liquid sample requirements, increased sensitivity, greater throughput, decreased cost and less procedural variation.
DMF technology is used to manipulate droplet-sized liquid volumes on a substrate or chip. While a variety of principles of operation exist, the most common methods utilize electrowetting in order to alter the surface energy of specific regions of the underlying substrate, thereby manipulating whether the liquid adheres to (wets) or is repelled by (forms droplets) the surface. This mechanism allows very small nanoliter droplet-sized samples to be controlled and moved across different areas of the substrate. By programming specific and increasingly complex steps for the sample, complicated laboratory procedures can be greatly scaled down and automated.
A number of applications currently use DMF, while numerous others are currently being researched and developed. Life sciences and biopharmaceutical end-users provide the most demand for DMF technology due to the value of high-throughput automation and variation reduction to these labs. Illumina is currently a leading vendor in DMF technology following its acquisition of digital microfluidics technology company, Advanced Liquid Logic (see IBO 7/31/13). Illumina’s NeoPrep Library Prep System utilizes DMF technology in order to automate library preparation for NGS applications. The NeoPrep reduces hands-on time in the lab and uses consumables called library cards as the microfluidic substrate, which plug into the NeoPrep instrument for control and analysis.
Additionally, DMF is being coupled with MS in order to provide either indirect off-line, direct off-line or in-line analysis in order to reduce solvent and reagent use, and analysis time. Similarly, DMF-based technology is also being integrated with NMR techniques in order to limit waste and prevent cross contamination. Immunoassays are another area where DMF platforms are finding an increasing number of applications. ELISA-on-a-chip platforms are promising for point-of-care and other applications, which can be conducted outside of traditional laboratory settings such as testing environmental or clinical samples in the field.
Digital Microfluidics at a Glance:
- Pharmaceutical and Biotechnology
- Hospital and Clinical