Three-dimensional digital scanner based on micromachined micromirror for the metrological measurement of the human ear canal

M. Prasciolu*, R. Malureanu, S. Cabrini, D. Cojoc, L. Businaro, A. Carpentiero, R. Kumar, E. Di Fabrizio

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Manufacturers of hearing aids have made initial testing of rapid prototyping of hearing aid shells using laser scans of ear impressions, but they have not performed any actual scans of the human ear canal. We report the direct scanning of the human external auditory canal by using an electromagnetically actuated torsion micromirror fabricated by using a micromachining technique as the scanner. This demonstrates the actual scanning of the human external auditory canal by a single integral microelectro-optical- mechanical system (MEOMS). A prototype three-dimensional (3D) scanning system was developed: It is based on the acquisition of optical range data by a conoscopic holographic laser interferometer using an electromagnetically actuated scanning MEOMS micromirror. A fabrication process, based on a poly(methylmethacrylate) sacrificial layer for the fabrication of a free-standing micromirror was used. Micromirror actuation was achieved by using a magnetic field generated with an electromagnetic coil stick. The micromirror and electromagnet coil assembly compose the opto-mechanical scanning probe used for entering the auditory canal. Based on an actual scan map, a 3D reconstructed digital model of the ear canal was built using a surface point distribution approach. The prototype system allows a no-invasive 3D imaging of the ear canal with spatial resolution in the 10 μm range. Fabrication of two complete hearing aids from in vivo ear canal scanning is also accomplished.

Original languageEnglish (US)
Pages (from-to)2990-2994
Number of pages5
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Issue number6
StatePublished - Nov 2005
Externally publishedYes

Bibliographical note

Funding Information:
The authors thank Amplifon SPA for financial support and assistance, and PHONAK for comparison analysis and hearing aid fabrication.

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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