On-chip sample preparation by electrowetting-on-dielectric digital microfluidics for matrix assisted laser desorption/ionization mass spectrometry

We present a novel sample preparation technique using electrowetting-based digital microfluidics for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). We demonstrate that critical functions, such as generation of droplets from reservoirs and sample purification can be achieved for standard MALDI-MS reagents and analytes by electrowetting-on-dielectric (EWOD) actuation. The results, collected using devices with droplets suspended in air (rather than oil (Pollack et al., 2000)), suggest that the tedious process of sample preparation can be automated on-chip for high-throughput proteomics and other applications of MALDI-MS.