Among the high-tech products of ETNA are the inverted-mesa (IM) crystal blanks. ETNA has developed original equipment and technology for thinning of AT-cut quartz blanks from initial thickness values of 60- 70 m to thickness values of the mesa part down to 3 to 5 m (in frequency terms up to the frequency of 500MHz) while retaining polish-class roughness and optical grade flatness of the mesa area.

ETNA manufactures IM fundamental mode quartz crystal units with the high Q and low dynamic resistance values. For example: fundamental mode quartz crystal units in the frequency range of 150 to160MHz have equivalent series resistance (ESR) values of 6 to 15 Ohm, and Q from 25000 to 45000.

A series of experiments to try ETNA's not-sealed IM telecommunication fundamental mode quartz crystal units as sensors was carried out. High Q and low ESR values help crystal to "bear" heavy mass-load of a sorbent retaining good piezoelectric properties. This allows rather conveniently to turn ETNA's commercial crystal units into sensors. In this experiments specially designed by ETNA oscillators for the "heavy mass-burdened" crystal units were used.

Attractive in IM fundamental mode quartz crystal sensors seems to be the fact that the thinner is the mesa the smaller is it's mass and the same change of mass on the surface of mesa produces more significant change in frequency, i.e. sensibility increases with the rise of frequency.

ETNA's participation in a possible project concerning research and development of quartz mass-sensors could include the following items:
- research, development and delivery of crystal units specially adapted for specific sensors;
- research, development and delivery of oscillators;
- other moments including technology and general design (if required).

ETNA COMPANY can produce now about 10 000 pcs / month of IM crystal units for sensors.