Detecting and/or mitigating the presence of particle contaminants in a MEMS device involves including MEMS structures that in normal operation are robust against the presence of particles but which can be made sensitive to that presence during a test mode prior to use, e.g., by switching the impedance of sensitive structures between an exceptionally sensitive condition during test and a normal sensitivity during operation; surrounding sensitive nodes with guard elements that are at the same potential as those nodes during operation, thereby offering protection against bridging particles, but are at a very different potential during test and reveal the particles by their resulting leakage currents; extending the sensitive nodes to interdigitate with or otherwise extend adjacent to the guard structures, which neither contribute to nor detract from the device operation but cover otherwise open areas with detection means during test; and/or converting benign areas in which particles might become trapped undetectably by electric fields during test to field-free regions by extending otherwise non-functional conductive layers so that the particles can then be moved into detection locations by providing some mechanical disturbance.