2-6 Sensors and Sensor Technology
for the communication of the measurement data. Usually, the readout coil is bigger than the coil of
th
e
im
planted
un
it
. i
s
is du
e,
on th
e
on
e
ha
nd,
to th
e
ne
ed
to oc
cupy
a sm
all
sp
ace
in
side
th
e
hu
man
bo
dy
an
d,
on th
e
ot
her
ha
nd,
to th
e
di
culty
of pr
operly
co
upling
th
e
tw
o
wi
ndings
. e re
adout
co
il
th
erefore
al
lows
fo
r
ha
ving
a gr
eater
ar
ea
re
lated
to th
e
co
upling
of th
e
ma
gnetic
e
ld,
bu
t
at th
e
ex
pense
of th
e
e
ciency
of po
wer
tr
ansfer
. To tr
ansmit
da
ta,
th
e
tr
ansponder
of th
e
im
planted
un
it
mo
dulates
th
e
ma
gnetic
e
ld
usi
ng
a da
mping
st
age
. It mo
dulates
th
e
co
il
vo
ltage
by va
rying
th
e
co
il’s
lo
ad
. A hi
gh
le
vel
(“
1”)
in
creases
th
e
cu
rrent
in
to
th
e
co
il
an
d
da
mps
th
e
co
il
vo
ltage
. A lo
w
le
vel
(“
0”)
de
crea ...