Ultrasonic transmission and reception from bulk-micromachined transducers

Citation
Pd. Harris et al., Ultrasonic transmission and reception from bulk-micromachined transducers, IEEE ULTRAS, 48(1), 2001, pp. 224-231
Citations number
18
Categorie Soggetti
Optics & Acoustics
Journal title
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
ISSN journal
08853010 → ACNP
Volume
48
Issue
1
Year of publication
2001
Pages
224 - 231
Database
ISI
SICI code
0885-3010(200101)48:1<224:UTARFB>2.0.ZU;2-5
Abstract
Acoustic transduction in air from two bulk-micromachined silicon structures is investigated. Both contain silicon diaphragms of the order of 2 mm(2) i n close proximity to a metallized substrate. One diaphragm is mass-loaded t he other is not. Their resonant frequencies (70 and 360 kHz) are dominated by squeeze film trapping of ambient air, and the 4 of each device is about 8. The lower frequency (LF) device is characterized by electrical and acous tic measurements using a calibrated microphone. Novel diagnostic methods th at exploit the non-linear nature of the transducer are described. The adequ acy of calibration by reciprocity is confirmed at 70 kHz and applied to the high frequency device. An insertion loss of 19 dB is measured, which compa res well with reports of other silicon-based transducers. Observed losses a re accounted for by squeeze-film damping applied to the diaphragm-substrate gap. The ability to control the bandwidth by the squeeze film effect, the good efficiency, and the relatively standard method of construction could m ake such ultrasonic transducers useful in specialist applications.