Fabrication and modal characterisation of large-area polymer membranes for acoustic MEMS devices

Luca Camellini, Alberto Torin, Asa'ad kareem edaan Al-masha'al, Graham Wood, Michael Newton, Rebecca Cheung, Enrico Mastropaolo

Research output: Contribution to journalLetterpeer-review

Abstract / Description of output

Bilayer polymer/metal suspended membranes made of poly(methyl methacrylate) (PMMA) and aluminium (Al) have been fabricated using
a wet transfer technique where a polyelectrolyte (polydiallyldimethylammonium chloride - PDAC) has been employed as sacrificial layer
to facilitate the detachment of the thin PMMA/Al layers from the substrate holders. In this way, free-standing PMMA/Al membranes with
outstanding diameter (3.5 mm) to thickness (400 nm) ratios of ~10^4 have been obtained. The membranes have been actuated mechanically
and electrothermally and their modal behaviour characterised using laser doppler vibrometry. The first five modes of vibrations have been
detected in the range of 2 – 25 kHz. The 2nd and 5th degenerate modes have been seen to split, probably due to nonuniform tension or mass
density. The membranes can achieve vibration amplitudes in the order of few tens of microns. When performing electro-thermal actuation it
has been observed that the amplitude of a single mode can be tuned by controlling the path of the electric current across the membrane.
Original languageEnglish
Pages (from-to)989-992
Number of pages4
JournalMicro and Nano Letters
Issue number7
Early online date3 Apr 2018
Publication statusPublished - 1 Jul 2018


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