Acoustic resonance sensor devices for radical species detection with enhanced filters

A method comprising:

• obtaining a base structure of a radical sensor comprising a piezoelectric resonator, the base structure comprising a piezoelectric material;
• and
• forming, on the base structure, a filter comprising a coating to selectively react with a radical species, wherein a resonant frequency of the radical sensor changes in response to reaction of the radical species to the filter, and wherein forming the filter comprises at least one of:
• doping an initial coating with a dopant to form the coating, using a base material and the dopant to deposit the coating, forming the coating to have a thickness that ranges from about 5 micrometers to about 50 micrometers, or forming the coating using a deposition process performed at a temperature ranging from about 150° C. to about 450° C.