<s>
Ultrasonic	B-Algorithm
transducers	I-Algorithm
and	O
ultrasonic	B-Algorithm
sensors	I-Algorithm
are	O
devices	O
that	O
generate	O
or	O
sense	O
ultrasound	B-Application
energy	O
.	O
</s>
<s>
Transmitters	O
convert	O
electrical	O
signals	O
into	O
ultrasound	B-Application
,	O
receivers	O
convert	O
ultrasound	B-Application
into	O
electrical	O
signals	O
,	O
and	O
transceivers	O
can	O
both	O
transmit	O
and	O
receive	O
ultrasound	B-Application
.	O
</s>
<s>
Ultrasound	B-Application
can	O
be	O
used	O
for	O
measuring	O
wind	O
speed	O
and	O
direction	O
(	O
anemometer	O
)	O
,	O
tank	O
or	O
channel	O
fluid	O
level	O
,	O
and	O
speed	O
through	O
air	O
or	O
water	O
.	O
</s>
<s>
Further	O
applications	O
include	O
:	O
humidifiers	O
,	O
sonar	B-Application
,	O
medical	B-Application
ultrasonography	I-Application
,	O
burglar	O
alarms	O
,	O
non-destructive	O
testing	O
and	O
wireless	B-Application
charging	I-Application
.	O
</s>
<s>
Ultrasound	B-Application
can	O
also	O
be	O
used	O
to	O
make	O
point-to-point	O
distance	O
measurements	O
by	O
transmitting	O
and	O
receiving	O
discrete	O
bursts	O
of	O
ultrasound	B-Application
between	O
transducers	O
.	O
</s>
<s>
This	O
technique	O
is	O
known	O
as	O
Sonomicrometry	O
where	O
the	O
transit-time	O
of	O
the	O
ultrasound	B-Application
signal	O
is	O
measured	O
electronically	O
(	O
ie	O
digitally	O
)	O
and	O
converted	O
mathematically	O
to	O
the	O
distance	O
between	O
transducers	O
assuming	O
the	O
speed	O
of	O
sound	O
of	O
the	O
medium	O
between	O
the	O
transducers	O
is	O
known	O
.	O
</s>
<s>
Ultrasonic	B-Algorithm
transducers	I-Algorithm
convert	O
alternating	O
current	O
(	O
AC	O
)	O
into	O
ultrasound	B-Application
and	O
vice	O
versa	O
.	O
</s>
<s>
The	O
transducers	O
typically	O
use	O
piezoelectric	B-Algorithm
transducers	I-Algorithm
or	O
capacitive	B-Algorithm
transducers	I-Algorithm
to	O
generate	O
or	O
receive	O
ultrasound	B-Application
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
capacitive	B-Algorithm
transducers	I-Algorithm
use	O
electrostatic	O
fields	O
between	O
a	O
conductive	O
diaphragm	O
and	O
a	O
backing	O
plate	O
.	O
</s>
<s>
The	O
beam	O
pattern	O
of	O
a	O
transducer	O
can	O
be	O
determined	O
by	O
the	O
active	O
transducer	O
area	O
and	O
shape	O
,	O
the	O
ultrasound	B-Application
wavelength	O
,	O
and	O
the	O
sound	O
velocity	O
of	O
the	O
propagation	O
medium	O
.	O
</s>
<s>
The	O
diagrams	O
show	O
the	O
sound	O
fields	O
of	O
an	O
unfocused	O
and	O
a	O
focusing	O
ultrasonic	B-Algorithm
transducer	I-Algorithm
in	O
water	O
,	O
plainly	O
at	O
differing	O
energy	O
levels	O
.	O
</s>
<s>
Since	O
piezoelectric	O
materials	O
generate	O
a	O
voltage	O
when	O
force	O
is	O
applied	O
to	O
them	O
,	O
they	O
can	O
also	O
work	O
as	O
ultrasonic	B-Algorithm
detectors	I-Algorithm
.	O
</s>
<s>
Ultrasound	B-Application
transmitters	O
can	O
also	O
use	O
non-piezoelectric	O
principles	O
.	O
</s>
<s>
A	O
capacitor	O
(	O
"	O
condenser	O
"	O
)	O
microphone	O
has	O
a	O
thin	O
diaphragm	O
that	O
responds	O
to	O
ultrasound	B-Application
waves	O
.	O
</s>
<s>
The	O
diaphragm	O
(	O
or	O
membrane	O
)	O
principle	O
is	O
also	O
used	O
in	O
the	O
relatively	O
new	O
micro-machined	O
ultrasonic	B-Algorithm
transducers	I-Algorithm
(	O
MUTs	O
)	O
.	O
</s>
<s>
These	O
devices	O
are	O
fabricated	O
using	O
silicon	O
micro-machining	O
technology	O
(	O
MEMS	B-General_Concept
technology	O
)	O
,	O
which	O
is	O
particularly	O
useful	O
for	O
the	O
fabrication	O
of	O
transducer	O
arrays	O
.	O
</s>
<s>
The	O
vibration	O
of	O
the	O
diaphragm	O
may	O
be	O
measured	O
or	O
induced	O
electronically	O
using	O
the	O
capacitance	O
between	O
the	O
diaphragm	O
and	O
a	O
closely	O
spaced	O
backing	O
plate	O
(	O
CMUT	B-Algorithm
)	O
,	O
or	O
by	O
adding	O
a	O
thin	O
layer	O
of	O
piezo-electric	O
material	O
on	O
the	O
diaphragm	O
(	O
PMUT	B-Algorithm
)	O
.	O
</s>
<s>
Ultrasonic	B-Algorithm
Transducers	I-Algorithm
are	O
also	O
used	O
in	O
acoustic	O
levitation	O
.	O
</s>
<s>
It	O
involves	O
transmitting	O
acoustic	O
waves	O
into	O
water	O
and	O
recording	O
the	O
time	O
interval	O
between	O
emission	O
and	O
return	O
of	O
a	O
pulse	O
;	O
the	O
resulting	O
time	O
of	O
flight	O
,	O
along	O
with	O
knowledge	O
of	O
the	O
speed	O
of	O
sound	O
in	O
water	O
,	O
allows	O
determining	O
the	O
distance	O
between	O
sonar	B-Application
and	O
target	O
.	O
</s>
<s>
This	O
information	O
is	O
then	O
typically	O
used	O
for	O
navigation	O
purposes	O
or	O
in	O
order	O
to	O
obtain	O
depths	O
for	O
charting	B-Application
purposes	O
.	O
</s>
<s>
Echo	O
sounding	O
is	O
effectively	O
a	O
special	O
purpose	O
application	O
of	O
sonar	B-Application
used	O
to	O
locate	O
the	O
bottom	O
.	O
</s>
<s>
Since	O
a	O
traditional	O
pre-SI	O
unit	O
of	O
water	O
depth	O
was	O
the	O
fathom	B-Algorithm
,	O
an	O
instrument	O
used	O
for	O
determining	O
water	O
depth	O
is	O
sometimes	O
called	O
a	O
fathometer	O
.	O
</s>
<s>
Medical	O
ultrasonic	B-Algorithm
transducers	I-Algorithm
(	O
probes	O
)	O
come	O
in	O
a	O
variety	O
of	O
different	O
shapes	O
and	O
sizes	O
for	O
use	O
in	O
making	O
cross-sectional	O
images	O
of	O
various	O
parts	O
of	O
the	O
body	O
.	O
</s>
<s>
The	O
transducer	O
may	O
be	O
used	O
in	O
contact	O
with	O
the	O
skin	O
,	O
as	O
in	O
fetal	O
ultrasound	B-Application
imaging	I-Application
,	O
or	O
inserted	O
into	O
a	O
body	O
opening	O
such	O
as	O
the	O
rectum	O
or	O
vagina	O
.	O
</s>
<s>
Clinicians	O
who	O
perform	O
ultrasound-guided	O
procedures	O
often	O
use	O
a	O
probe	O
positioning	O
system	O
to	O
hold	O
the	O
ultrasonic	B-Algorithm
transducer	I-Algorithm
.	O
</s>
<s>
Compared	O
to	O
other	O
medical	O
imaging	O
modalities	O
,	O
ultrasound	B-Application
has	O
several	O
advantages	O
.	O
</s>
<s>
It	O
provides	O
images	O
in	O
real-time	O
,	O
is	O
portable	B-Algorithm
,	O
and	O
can	O
consequently	O
be	O
brought	O
to	O
the	O
bedside	O
.	O
</s>
<s>
Owing	O
to	O
these	O
drawbacks	O
,	O
novel	O
wearable	O
ultrasound	B-Application
implementations	O
are	O
gaining	O
popularity	O
.	O
</s>
<s>
Ultrasonic	B-Algorithm
sensors	I-Algorithm
can	O
detect	O
the	O
movement	O
of	O
targets	O
and	O
measure	O
the	O
distance	O
to	O
them	O
in	O
many	O
automated	O
factories	O
and	O
process	O
plants	O
.	O
</s>
<s>
Ultrasonic	B-Algorithm
sensors	I-Algorithm
are	O
widely	O
used	O
in	O
cars	O
as	O
parking	B-Algorithm
sensors	I-Algorithm
to	O
aid	O
the	O
driver	O
in	O
reversing	O
into	O
parking	O
spaces	O
.	O
</s>
<s>
Because	O
ultrasonic	B-Algorithm
sensors	I-Algorithm
use	O
sound	O
rather	O
than	O
light	O
for	O
detection	O
,	O
they	O
work	O
in	O
applications	O
where	O
photoelectric	B-Algorithm
sensors	I-Algorithm
may	O
not	O
.	O
</s>
<s>
As	O
well	O
,	O
target	O
color	O
or	O
reflectivity	O
do	O
not	O
affect	O
ultrasonic	B-Algorithm
sensors	I-Algorithm
,	O
which	O
can	O
operate	O
reliably	O
in	O
high-glare	O
environments	O
.	O
</s>
<s>
Passive	O
ultrasonic	B-Algorithm
sensors	I-Algorithm
may	O
be	O
used	O
to	O
detect	O
high-pressure	O
gas	O
or	O
liquid	O
leaks	O
,	O
or	O
other	O
hazardous	O
conditions	O
that	O
generate	O
ultrasonic	O
sound	O
.	O
</s>
<s>
An	O
ultrasonic	B-Algorithm
transducer	I-Algorithm
is	O
affixed	O
to	O
a	O
stainless	O
steel	O
pan	O
which	O
is	O
filled	O
with	O
a	O
solvent	O
(	O
frequently	O
water	O
or	O
isopropanol	O
)	O
.	O
</s>
