Biomedical Engineering Reference
In-Depth Information
Alternatively, actively vibrating-mesh nebulizers generate aerosols by
employing ―micropump‖ technology that consists of an aerosol generator of up
to 1,000 electroformed dome-shaped apertures surrounded by a ceramic
vibrational element (Fink et al., 2001a; Gopalakrishnan and Uster; 2001;
Dhand, 2002) (Figure 12). The vibrational element expands and contracts
when an electrical current is applied, which results in upward and downward
movements of the mesh by a few micrometers (Dhand, 2002). This technology
generates slow-moving aerosols with the droplet size and nebulization rate
being dependent on the aperture size of the mesh (Gopalakrishnan and Uster,
2001) and fluid physicochemical properties (Ghazanfari et al., 2007; Elhissi et
al., in press). The Aeroneb Pro (Aerogen, Ireland) (Figure 12) nebulizer uses
this technology and is recommended for use during mechanical ventilation
since it can be connected to the inspiratory limb of the ventilator circuit whilst
nebulization is continuously operating (Fink et al., 2001a).
(Source: Ghazanfari et al., 2007).
Figure 12. Design of the Aeroneb Pro nebulizer which operates by utilizing an
Aerogen aerosol generator (OnQTM) comprising a piezoceramic vibrational element
surrounding the mesh plate.
In contrast to ultrasonic and air-jet nebulizers, the fluid temperature does
not change during atomization (Fink et al., 2001a). Aerogen vibrating-mesh
nebulizers have been reported to be as efficient as jet nebulizers in delivering
suspensions of ciclosporin (Eskandar et al., 2003), steroid (Fink et al., 2001b;
Fink and Simmons, 2004) and liposomes (Elhissi et al., 2006; 2007; Elhissi et
al., in press).
As an alternative to the micropump technology, TouchSpray technology
can also generate slow moving aerosols. The novel vibrating-mesh (electronic)
nebulizer eFlow (Pari, GmbH, Germany) has a TouchSpray atomizing head
which incorporates a piezoelectric actuator and a perforated membrane which
