High Sensitivity Micropillar Electrosprayionization Chip Fabricated of Silicon

We have designed, fabricated and tested a micropillar array electrospray ionization (muPESI) chip for mass spectrometer (MS) analysis of drugs and biomolecules. The chip has a lidless microstructured channel that contains a perfectly ordered array of micropillars. The typical sample volume is 2.5 mul and the sample flow in the channel is spontaneous. The limit of detection for verapamil measured with MS/MS was 30 pmol/1. The system shows also quantitative linearity (r =0.997) with linear dynamic range of at least six orders of magnitude and good stability (standard deviation < 4%) at measurement for 60 minutes.