What is digital microfluidics (DMF)?
Digital microfluidics is a method to programmably manipulate tiny droplets of liquid by electrical control of surface tension (or electrowetting). This innovative technology for liquid handling - with no fixed channels or pumps or valves, and fully automated in software - performs tests on a disposable cartridge. Droplets are discretely transported within a network of electrodes on the cartridge by strategically applying or removing voltage from adjacent electrodes.
The following video shows simple droplet operations enabling a digital microfluidic paradigm including transportation, splitting, merging, and dispensing from a larger reservoir:
Digital microfluidics builds complex systems on the foundation of these simple droplet operations. All of these operations can be performed with just a circuit board controlling the voltages applied to the electrodes. Building on these basic operations, complex droplet operations can be performed including mixing, diluting, washing, and thermal cycling. These complex operations can then be employed in a PCR assay in a testing platform that is designed for a specific use case.
Digital microfluidics brings unique benefits to diagnostic testing and newborn screening. Here are 5 things you should know about testing with DMF:
1. Low sample volume
Digital microfluidics is performed using “micro” volumes of sample and reagent. For example, diagnostic tests require just 50 microliters of blood from the patient (about the size of a raindrop), which is especially precious for tiny babies in the neonatal intensive care units. Each test is performed using only 1 microliter out of the 50 microliters, leaving room for multiple tests. DMF enables neonatologists to maximize the diagnostic yield from a drop of blood. In newborn screening with DMF, multiple tests can be performed from one punch of a dried blood spot specimen.
DMF manipulates sub-microliter size droplets, which enable fast kinetics. These droplets are also manipulated rapidly in a fully-automated system which enable fast results. Additionally, multiple assay steps are performed in parallel speeding up the time to complete the assays.
3. Multiple tests at the same time
Programmable control of liquids allows multiple assays to be performed on the same cartridge simultaneously. This video shows a digital microfluidics cartridge performing 4 enzymatic assays; the droplets travel in crisscrossing pathways without affecting the enzymatic activity between droplets.
4. Multifunctional assay methods
Digital microfluidics has the capability to support multifunctional test methods – including molecular, immunoassay, and chemistry. Each bioassay can be spatially and spectrally multiplexed to perform simultaneously on a single sample and using the same cartridge.
5. Inexpensive instruments with small footprint
Testing platforms powered by digital microfluidics reduce reagent costs since they only require tiny volumes. DMF instruments do not have mechanical pumps or valves for liquid handling and are, therefore, small and portable.
Baebies scientists have published over 100 peer-reviewed publications and conference presentations on our DMF work outlining the core technology, assays, and clinical studies. See this 2020 publication: Digital Microfluidic Platform to Maximize Diagnostic Tests with Low Sample Volumes from Newborns and Pediatric Patients