Simple, sensitive, frequency-tuned drop detector

A drop detector, comprising:

• a. a cover plate, defining through itself an oblong first slot;
• b. a substrate, defining through itself an oblong second slot sized to be smaller than the oblong first slot:
• c. a membrane:
• i. fabricated from a piezoelectric material which generates an electric signal in response to being impacted by a drop;
• ii. frequency tunable to a range of selected resonant frequencies;
• iii. secured at least at two locations between the cover plate and the substrate;
• iv. formed with a floating region:
• (1) having a generally rectangular area defined by:
• (a) a pair of short ends, opposite one another, defining the shorter width dimensions of the floating region;
• and
• (b) a pair of membrane lengths, opposite one another, defining the longer length dimensions of the floating region;
• (2) suspended across and between the slots with the pair of short ends being unsecured and therefore free to move;
• (3) aligned with the membrane lengths generally parallel with the long dimensions of the slots;
• (4) positioned to be impacted by and thereby detect the drop;
• d. a conductor means:
• i. electrically coupled to the membrane;
• ii. formed for transmitting to an external environment the electric signal generated by the membrane;
• e. a wiper:
• i. movably disposed in the vicinity of the floating region of the membrane;
• ii. formed for periodically being moved across the surface of the membrane to push the accumulated drops if any toward and through the first port and the second port;
• and
• f. an electromagnetic shield:
• i. coupled to the detector;
• ii. operable to attenuate an electromagnetic field if any that might otherwise degrade the performance of the membrane when detecting the drops.