Biomaterials for MEMS

266 Color Inserts

Ϭ͘Ϭϭ

Ϭ͘ϭ

ϭ

ϭϬ ϭϱ ϮϬ Ϯϱ ϯϬ

Ϭ͘Ϯϱϯ

Ϭ͘Ϯϳϱ

Ϭ͘Ϯϴ

Ϭ͘ϯ

EĂ

ϯ

WK

ϰ

ŽŶĐĞŶƚƌĂƚŝŽŶ΀ŵŽůͬ>΁

sŝƐĐŽƐŝƚLJ;WĂ ƐͿ

dĞŵƉĞƌĂƚƵƌĞ;ΣͿ

Figure 6.3 Viscosity as a function of temperature for high concentrations of sodium

phosphate in a 15 wt% Pluronic F127 solution in water from cone and plate viscometry

at controlled shear stress (0.6 Pa s).

110

Figure 6.5 A schematic illustration of the principle of an active valve using a thermally

responsive fluid in a microfluidic network. (a) Fluid from one channel is d iverted into two

channels at a channel bifurcation; (b) activating an integrated heater leads to localized gel

formation in the corresponding microchannel, which subsequently blocks this channel to

flow.

SO13997_text.indd 274SO13997_text.indd 274 26/01/2011 3:51 PM26/01/2011 3:51 PM

Color Inserts 267

Figure 6.7 A schematic cross-section of the microfluidic device shown in Fig. 6.6. The left-

hand side shows the cross-section across a heater in the channel, while the right-hand side

shows a cross-section further away from the channel, through an aluminum lead.

D

E

Figure 6.9 The flow field at the channel bifurcation shown in Fig. 6.6. The velocities

were evaluated from images of the seed particles as in Fig. 6.8 using PIV; (a) before valve

actuation, (b) 33 ms later; blue: below 40 μm/s, green: 40–80 μm/s, yellow: 80–120 μm/s,

orange: 120–160 μm/s.

SO13997_text.indd 275SO13997_text.indd 275 26/01/2011 3:51 PM26/01/2011 3:51 PM

268 Color Inserts

Figure 6.10 Experimental setup for the demonstration of passive flow control using ther-

mally responsive Pluronic solutions at constant flow rate in microchannels.

Figure 6.14 Top view of a microfluidic device. Pluronic solution and saline solution are

introduced in a 10 μm high microchannel at T

a

=24

◦

C. Gel formation occurs in the center

of the channel. The Pluronic stream is seeded with fluorescent particles.

SO13997_text.indd 276SO13997_text.indd 276 26/01/2011 3:51 PM26/01/2011 3:51 PM

Color Inserts 269

Figure 6.16 Thickness of the gel wall along the channel for different experimental condi-

tions.

Figure 7.5 BioMEMS multi-array prototype implanted subcutaneously in a rodent model.

The local environment had encapsulated the device in an attempt to isolate it from the body

(28 days post-implantation).

SO13997_text.indd 277SO13997_text.indd 277 26/01/2011 3:51 PM26/01/2011 3:51 PM

270 Color Inserts

Figure 7.8 BioMEMS micro-array prototype. The inner-reservoir surface area is larger than

it appears from a top view (A). The activation of the entire multi-array reservoir system

leads to dissolution of the reservoir sealing membrane, release of the drug, and the onset of

a “new” inflammatory response initiated by the exposed surface of the inner reservoir (B).

Figure 8.1 Amount of protein adsorption on a given oligoether SAM on gold normalized

to the amount of protein adsorbed on a monolayer of hexa-decanethiol on gold (100%)

versus advancing aqueous contact angle of the SAM. Symbols: red

,EG

2

OH; orange,

EG

3

OH; green+,EG

6

OH; blue,TRI

3

OH; blue ,EG

1

OMe; green,EG

2

OMe; light blue •,

EG

3

OMe; red ×,EG

6

OMe; blue ,TRI

3

OMe; red ×,PRO

2

OMe; blue♦,PRO

3

OMe; orange

+,PRO

4

OMe; purpl,EG

3

OEt; green◦,EG

6

OEt; blue,EG

3

OPr; green,EG

6

OPr; blue •,

EG

3

OBu. Images adapted from Ref. 54.

SO13997_text.indd 278SO13997_text.indd 278 26/01/2011 3:51 PM26/01/2011 3:51 PM