Figure 2: Electrospray testing environment depicting electrospray ionization to produce a flux of neutral and charged analytes.

(a) BT ions shown in light blue are selected to deposit on domain 1 in step 1. (b) 4-FBT ions shown in light green are selected to deposit on domain 2 in step 2. Circular 1 μm in diameter openings in the positively charged photoresist layer (red) act as a nanolens array, which concentrate the two analytes in predetermined sensing spots. The+sign on the red layer represents primary ionized carrier gas molecules. Switches marked as ‘open’ and ‘close’ are used to attract the analyte to the respective domains.