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Cascade Avalanche Sorbent Plate ARray (CASPAR), a micromachined hotplate coated with sorbent polymer, has been demonstrated earlier as a selective preconcentrator for chemical agents and explosives. Up to two orders of magnitude increase in sensitivity has been established by incorporating CASPAR as a front end-modification to commercial detectors. Experimental evidence obtained via thermal imaging and fluorescent particle flow tagging suggests that an 8.5 mm times 8.5 mm current hotplate design is sub-optimal due to non-uniformities in the heating and vapor/particle collection profiles. In this study, we discuss the CASPAR design optimization with the aim to enhance the collection efficiency of hazardous chemical vapor while maintaining thermal stability and precise control before injection of a focused pulse of analyte into a detector.