Biomedical Engineering Reference
In-Depth Information
3.3.3. Vibrating-Mesh Nebulizers
Vibrating-mesh nebulizers, or simply called mesh nebulizers, employ a
vibrating-mesh or a plate with multiple apertures to generate the aerosol
(Dhand, 2002). These devices are different in design, performance, and the
mechanism employed to generate the aerosols through the mesh pores.
However, all are hand-held and battery operated. The vibrating-mesh
nebulizers are classified as passively vibrating and actively vibrating mesh
nebulizers.
The Omron MicroAir NEU22 (Figure 11) is an example of passively
vibrating-mesh nebulizers. This nebulizer incorporates a high frequency
vibrating piezoelectric crystal attached to a transducer horn that transmits the
vibrations to a perforated plate on top of it. This causes ―passive‖ vibrations of
the mesh, resulting in the extrusion of the medication fluid through the plate
apertures (each has a diameter of approximately 3µm) and the production of
aerosol droplets (Dhand, 2002) (Figure 11). The mesh comprises up to 6,000
tapered holes which amplify the vibrations of the transducer horn in contact
with fluid and hence minimizes the energy required to generate the aerosol
(Dhand, 2002).
(Source: Ghazanfari et al., 2007).
Figure 11. Design of the Omron MicroAir NE-U22 nebulizer. The vibrating element
comprises a piezoelectric crystal, transducer horn and the mesh. The nebulizer
reservoir comprises the medication bottle, and the vibrating structures.
The Omron NE-U22 nebulizer produces a very high output so that
medication remains in the reservoir may be negligible (Dhand, 2002, Kishida
et al., 2003; Ismail and Chrystyn, 2004; Elhissi and Taylor, 2005; Elhissi et al.,
2006). The NE-U22 nebulizer is also highly successful in delivering
suspensions (Yoshiyama et al., 2002) and liposomes (Elhissi and Taylor, 2005;
Elhissi et al., 2006).
