The positioning stage is a single block three tier design; (a) a blueprint of the fully assembled device with the top tier transparent; (b) a photograph of the middle tier housing all of the mechanical components and sensors.
The control of the system consisting of the trajectory generator, inner velocity, and outer position loops. The trajectory generator generates both position and velocity commands, with the velocity gain K VFF ; the main loop of the control scheme is a proportional only controller with K PP proportional gain and K GP position scaling factor; the inner loop is a proportional integral controller with K PV proportional and K IV integral gains, K A amp and K GV velocity scaling factors, K J motor torque, and J inertia constants.
Final assembly of the positioning device; (a) lateral view of the stage in its fully compressed form; (b) mounted on the back plate of the MALDI source; (c) inside the MALDI source with a target next to accumulation hexopole (gas inlets for vibrational cooling are seen right next to the plate).
Software control interface; (a) a custom-built dedicated application for manual control of the device; (b) stage control GUI integrated into the AWG workflow based data acquisition and control system.
Performance evaluation analysis of the system. Blue is the position plot of the stage superimposed with the corresponding error (red).
An imaging experiment conducted on the simple tryptic/CNBr digest spotted on a MALDI target; (a) the plate after the sample deposition; (b) through (l) spatial distribution of the compounds with m/z's of 961, 1101, 1201, 1206, 1440, 1457, 1800, 1821, 1933, 2368, and 2593 Da, respectively.
Results of the “oversampling” experiment with the roster size of 50 microns conducted on the 50:50 mixture of bradykinin and angiotensin; (a) the target spot after the sample deposition; (b) spatial distribution of bradykinin at 904 Da; (c) spatial distribution of angiotensin at 1033 Da.
Results of the imaging experiments on the rat brain section (a) with roster sizes 300 (I) and 150 (II), monitoring spatial distribution of putative lipids at 827 Da (b), 768 Da (c), and 773 Da (d).
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