Laser desorption ionization (LDI) silicon nanopost array chips fabricated using deep UV projection lithography and deep reactive ion etching

Deep UV projection lithography (DUV-PL) and deep reactive ion etching (DRIE) processes are used to fabricate silicon nanopost surfaces for laser desorption ionization mass spectrometry (LDI-MS). Described here is a fabrication process that is amenable to mass production of silicon nanopost array (NAPA) devices optimized for laser desorption ionization mass spectrometry of small molecules less than 2 kDa, suitable for pharmaceutical and metabolomics applications. The resulting devices exhibit excellent performance for analysis and quantitation of pharmaceutical drugs over at least four orders of magnitude dynamic range, with very good limits of detection and lower limits of quantitation. For metabolite analysis, these devices also exhibit improved spectral quality over MALDI-MS which suffers from noise from the chemical matrix. With the ability to perform a one-step sample spotting, these devices become extremely useful for high throughput workflows afforded by MALDI mass spectrometry platforms.