Biomedical Engineering Reference
In-Depth Information
(a)
(b)
IDT
(c)
(d)
FIGURE 8.4
SAW microfluidics based on a hydrophobically treated LiNbO
3
device: (a) SAW streaming pattern; (b) droplet
pumping; (c) droplet jumping from surface; (d) droplet ejection.
2
∆
ρ
ρ
(8.3)
2
P
=
ρ
v
o s
o
where
ρ
o
is the liquid density and
Δρ
is the slight density change due to the acoustic pres-
sure. The generated acoustic pressure can create significant acoustic streaming in a liq-
uid and result in liquid mixing, pumping, ejection and atomization (Newton et al., 1999)
(see Figure 8.4, for examples). This pressure facilitates rapid liquid movement and also
internal agitation that speed up biochemical reactions, minimize nonspecific biobinding,
and accelerate hybridization reactions in protein and DNA analysis, which are commonly
used in proteomics and genomics (Toegl
et al., 2003; Wixforth et al., 2004). SAW-based liq-
uid pumps and mixers (Tseng et al., 2006; Sritharan et al., 2006), droplet positioning and
manipulation (Sano et al., 1998), droplet ejection and atomization systems (Chono et al.,
2004; Murochi
et al., 2007), and fluidic dispenser arrays (Strobl et al., 2004) have been pro-
posed and developed. They have distinct advantages: a simple device structure, no moving
parts, electronic control, high speed, programmability, manufacturability, remote control,
compactness, and high frequency response (Renaudin et al., 2006; Togle et al., 2004; Franke
and Wixforth,
2008).
SelectionofBulkMaterialsorThinFilms
Acoustic wave devices can be used for both biosensing and microfluidics applications,
which are two of the major components for lab-on-a-chip systems. Therefore, it is attrac-
tive to develop lab-on-chip biodetection platforms using acoustic wave devices because
