Biomedical Engineering Reference
In-Depth Information
promising material for the technology, PS also excites great interest among
scientists working with biosensors aimed to detect a biological substance of
quickly and in small quantities. h is is critically important for the express
diagnostics of diseases and environmental monitoring. Several methods
have been proposed to obtain PS and to use its properties at the creation
of dif erent devices [9-20]. Earlier [10-16] we have informed about the
development of a biosensor based on the PS PhL. It was demonstrated too
[9] the possibility using for the creation of an biosensor for quick detection
of myoglobin (Mb) as one of markers of the heart failure [9, 21].
13.2.4.1
Sensor Construction, Preparation of PS Samples and
Reactive Used [9]
h e PS samples with the size about 4×4 mm
2
, were obtained from mono-
crystalline silicon of
p
-type (the resistance about 10 ῼ/cm). h ey were
treated by laser beam YAG:Nd-laser (with the λ 1.06 mm; impulse dura-
tion t=5×10-4c; E=0.5J) and then chemically etched in a solution of
HF:HNO:H
2
O (volume ration 1:3:5) during 5-40 min at the room tem-
perature. h en silicon was passivated. PS was characterized by the size of
pores equal to 10-100 nm. PS PhL was excited by He-Cd laser (with λ 440
nm, P = 0.001 W) and measured by the standard monochromator. h e
visible PhL had λ equal to 650 nm and its time decay was described by
“stretch” exponent. Samples of PS were washed several times with distilled
water, then with absolute alcohol and at last they were dried at room tem-
perature (Figure 13.4).
Monocrystaline Silicon
(p-type,
ρ
= 10
(
A
)
(
B
)
1
x cm)
2
3
Laser Irradiation
(YAG: Nd laser;
λ
=1.06 m;
τ
= 2x10
-4
c; E = 0.3
J)
Chemical Treatment
(HF : HNO
4
: H
2
O = 1 : 3 : 5), 3-10
Porous Silicon
(sample size: 4x4 mm
2
; pore diameter: 50-400
nm)
Photoluminescence Recording
(He-Cd laser;
9
4
5
=440 nm; P = 0.001
W)
λ
6
7
Figure 13.4
Block-schemes of PS fabrication (A) and the set-up for PS PL measurement
(B) where: 1 - He-Cd laser and N2-1aser, 2 - modulator, 3 - prism, 4 - mirror, 5 - quartz
cell, 6 - PS-sample, 7 - spectrophotometer, 8 - photomultiplier, 9 - computer.
