Biomedical Engineering Reference
In-Depth Information
FIGURE 9.1
Nitinol stents showing kink resistance of a nitinol stent (images courtesy of Abbott Laboratories).
anastomosis (anastomosis ring), homeostasis (bleeding control clip), dissection (scissors),
ablation (multiple radiofrequency electrodes), surgical materials delivery, and hernia
repair. These include (1) curved surgical instruments—a variable curvature spatula for
laparoscopic surgery (Figure 9.2; Cuschieri et al., 1991); (2) suturing devices—for tissue
suturing in self-closing clips (Figure 9.3; Song et al., 2002; Ng et al., 2003); (3) bleeding con-
trol devices—SMA clip gastrointestinal lesion, perforation, and bleeding (see Figure 9.4;
Ovesco Endoscopy GmbH, Tubingen, Germany; Raju and Gajula, 2004; Kirschniak et al.,
2007).
The early applications of nitinol in orthopedic surgery were staples and clamps to treat
adolescent scoliosis and bone fractures (Musialek et al., 1998). Recent development of
porous nitinol has shown good biocompatibility and excellent bone ingrowths that could
be used as ideal bone substitute (Rhalmi et al., 1999). In the urological field, an SMA ureter
stent was used in 15 patients to treat ureter stricture with encouraging results (Chonan et
al., 1997). The endovascular device with shape memory function might be a promising tool
for treating ischemia stroke without the need for infusion of clot-dissolving drugs (Small
et al., 2007). The current trend of surgical technologies is toward less invasiveness or non-
scar diagnostics and treatment, and shape memory technology continues to find exciting
applications.
Thin Film TiNi SMAs
For microelectromechanical system (MEMS) and biomedical applications, thin film-based
SMAs possess many desirable properties, such as high-power density (up to 10 J/cm
3
), the
(a)
(b)
(c)
Superelastic nitinol blade
Superelastic nitinol wire
Flexible
nitinol drive
FIGURE 9.2
Variable-curvature devices for laparoscopic surgery. (a) Dissecting spatula, (b) suture passer, (c) flexible drive
for an articulating needle holder. (From Cuschieri et al.,
Surg. Endosc.
, 5, 179, 1991, reproduced with permission
from Springer.)
