<s>
In	O
electrical	O
engineering	O
,	O
capacitive	B-Device
sensing	I-Device
(	O
sometimes	O
capacitance	O
sensing	O
)	O
is	O
a	O
technology	O
,	O
based	O
on	O
capacitive	O
coupling	O
,	O
that	O
can	O
detect	O
and	O
measure	O
anything	O
that	O
is	O
conductive	O
or	O
has	O
a	O
dielectric	O
constant	O
different	O
from	O
air	O
.	O
</s>
<s>
Many	O
types	O
of	O
sensors	B-Application
use	O
capacitive	B-Device
sensing	I-Device
,	O
including	O
sensors	B-Application
to	O
detect	O
and	O
measure	O
proximity	B-Device
,	O
pressure	B-Algorithm
,	I-Algorithm
position	I-Algorithm
and	I-Algorithm
displacement	I-Algorithm
,	O
force	B-Algorithm
,	O
humidity	O
,	O
fluid	B-Algorithm
level	I-Algorithm
,	O
and	O
acceleration	O
.	O
</s>
<s>
Human	B-General_Concept
interface	I-General_Concept
devices	I-General_Concept
based	O
on	O
capacitive	B-Device
sensing	I-Device
,	O
such	O
as	O
touchpads	B-Application
,	O
can	O
replace	O
the	O
computer	B-Device
mouse	I-Device
.	O
</s>
<s>
Digital	O
audio	O
players	O
,	O
mobile	O
phones	O
,	O
and	O
tablet	B-Device
computers	I-Device
will	O
sometimes	O
use	O
capacitive	B-Device
sensing	I-Device
touchscreens	B-Device
as	O
input	O
devices	O
.	O
</s>
<s>
Capacitive	B-Device
sensors	I-Device
can	O
also	O
replace	O
mechanical	O
buttons	O
.	O
</s>
<s>
A	O
capacitive	O
touchscreen	B-Device
typically	O
consists	O
of	O
a	O
capacitive	B-Device
touch	I-Device
sensor	I-Device
along	O
with	O
at	O
least	O
two	O
complementary	O
metal	B-Architecture
–	I-Architecture
oxide	I-Architecture
–	I-Architecture
semiconductor	I-Architecture
(	O
CMOS	B-Device
)	O
integrated	O
circuit	O
(	O
IC	O
)	O
chips	O
,	O
an	O
application-specific	O
integrated	O
circuit	O
(	O
ASIC	O
)	O
controller	B-Architecture
and	O
a	O
digital	B-Architecture
signal	I-Architecture
processor	I-Architecture
(	O
DSP	O
)	O
.	O
</s>
<s>
Capacitive	B-Device
sensing	I-Device
is	O
commonly	O
used	O
for	O
mobile	O
multi-touch	B-Application
displays	O
,	O
popularized	O
by	O
Apple	O
's	O
iPhone	B-Device
in	O
2007	O
.	O
</s>
<s>
Capacitive	B-Device
sensors	I-Device
are	O
constructed	O
from	O
many	O
different	O
media	O
,	O
such	O
as	O
copper	O
,	O
indium	O
tin	O
oxide	O
(	O
ITO	O
)	O
and	O
printed	O
ink	O
.	O
</s>
<s>
Copper	O
capacitive	B-Device
sensors	I-Device
can	O
be	O
implemented	O
on	O
standard	O
FR4	O
PCBs	O
as	O
well	O
as	O
on	O
flexible	O
material	O
.	O
</s>
<s>
ITO	O
allows	O
the	O
capacitive	B-Device
sensor	I-Device
to	O
be	O
up	O
to	O
90%	O
transparent	O
(	O
for	O
one	O
layer	O
solutions	O
,	O
such	O
as	O
touch	O
phone	O
screens	O
)	O
.	O
</s>
<s>
Size	O
and	O
spacing	O
of	O
the	O
capacitive	B-Device
sensor	I-Device
are	O
both	O
very	O
important	O
to	O
the	O
sensor	O
's	O
performance	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
capacitive	B-Device
sensing	I-Device
systems	O
:	O
mutual	O
capacitance	O
,	O
where	O
the	O
object	O
(	O
finger	O
,	O
conductive	O
stylus	B-Device
)	O
alters	O
the	O
mutual	O
coupling	O
between	O
row	O
and	O
column	O
electrodes	O
,	O
which	O
are	O
scanned	O
sequentially	O
;	O
and	O
self	O
-	O
or	O
absolute	O
capacitance	O
where	O
the	O
object	O
(	O
such	O
as	O
a	O
finger	O
)	O
loads	O
the	O
sensor	O
or	O
increases	O
the	O
parasitic	O
capacitance	O
to	O
ground	O
.	O
</s>
<s>
The	O
sensor	O
's	O
controller	B-Architecture
can	O
determine	O
the	O
location	O
of	O
the	O
touch	O
indirectly	O
from	O
the	O
change	O
in	O
the	O
capacitance	O
as	O
measured	O
from	O
the	O
four	O
corners	O
of	O
the	O
panel	O
:	O
the	O
larger	O
the	O
change	O
in	O
capacitance	O
,	O
the	O
closer	O
the	O
touch	O
is	O
to	O
that	O
corner	O
.	O
</s>
<s>
With	O
no	O
moving	O
parts	O
,	O
it	O
is	O
moderately	O
durable	O
,	O
but	O
has	O
low	O
resolution	O
,	O
is	O
prone	O
to	O
false	O
signals	O
from	O
parasitic	O
capacitive	O
coupling	O
,	O
and	O
needs	O
calibration	B-General_Concept
during	O
manufacture	O
.	O
</s>
<s>
Projected	O
capacitive	O
touch	O
(	O
PCT	O
)	O
technology	O
is	O
a	O
capacitive	O
technology	O
which	O
allows	O
more	O
accurate	O
and	O
flexible	O
operation	O
,	O
by	O
etching	B-Algorithm
the	O
conductive	O
layer	O
.	O
</s>
<s>
An	O
X-Y	O
grid	O
is	O
formed	O
either	O
by	O
etching	B-Algorithm
one	O
layer	O
to	O
form	O
a	O
grid	O
pattern	O
of	O
electrodes	O
,	O
or	O
by	O
etching	B-Algorithm
two	O
separate	O
,	O
parallel	O
layers	O
of	O
conductive	O
material	O
with	O
perpendicular	O
lines	O
or	O
tracks	O
to	O
form	O
the	O
grid	O
;	O
comparable	O
to	O
the	O
pixel	B-Algorithm
grid	O
found	O
in	O
many	O
liquid	B-Device
crystal	I-Device
displays	I-Device
(	O
LCD	B-Device
)	O
.	O
</s>
<s>
Depending	O
on	O
the	O
implementation	O
,	O
an	O
active	O
or	O
passive	B-Device
stylus	I-Device
can	O
be	O
used	O
instead	O
of	O
or	O
in	O
addition	O
to	O
a	O
finger	O
.	O
</s>
<s>
Mutual	O
capacitive	B-Device
sensors	I-Device
have	O
a	O
capacitor	O
at	O
each	O
intersection	O
of	O
each	O
row	O
and	O
each	O
column	O
.	O
</s>
<s>
Bringing	O
a	O
finger	O
or	O
conductive	O
stylus	B-Device
near	O
the	O
surface	O
of	O
the	O
sensor	O
changes	O
the	O
local	O
electric	O
field	O
which	O
reduces	O
the	O
mutual	O
capacitance	O
.	O
</s>
<s>
Mutual	O
capacitance	O
allows	O
multi-touch	B-Application
operation	O
where	O
multiple	O
fingers	O
,	O
palms	O
or	O
styli	O
can	O
be	O
accurately	O
tracked	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
Self-capacitance	O
sensors	B-Application
can	O
have	O
the	O
same	O
X-Y	O
grid	O
as	O
mutual	O
capacitance	O
sensors	B-Application
,	O
but	O
the	O
columns	O
and	O
rows	O
operate	O
independently	O
.	O
</s>
<s>
The	O
capacitance	O
to	O
be	O
sensed	O
forms	O
a	O
portion	O
of	O
the	O
oscillator	O
's	O
RC	B-Algorithm
circuit	I-Algorithm
or	O
LC	O
circuit	O
.	O
</s>
<s>
Capacitive	O
touchscreens	B-Device
are	O
more	O
responsive	O
than	O
resistive	B-Device
touchscreens	I-Device
(	O
which	O
react	O
to	O
any	O
object	O
since	O
no	O
capacitance	O
is	O
needed	O
)	O
,	O
but	O
less	O
accurate	O
.	O
</s>
<s>
However	O
,	O
projective	O
capacitance	O
improves	O
a	O
touchscreen	B-Device
's	O
accuracy	O
as	O
it	O
forms	O
a	O
triangulated	O
grid	O
around	O
the	O
point	O
of	O
touch	O
.	O
</s>
<s>
A	O
standard	O
stylus	B-Device
cannot	O
be	O
used	O
for	O
capacitive	B-Device
sensing	I-Device
,	O
but	O
special	O
capacitive	O
stylus	B-Device
,	O
which	O
are	O
conductive	O
,	O
exist	O
for	O
the	O
purpose	O
.	O
</s>
<s>
One	O
can	O
even	O
make	O
a	O
capacitive	O
stylus	B-Device
by	O
wrapping	O
conductive	O
material	O
,	O
such	O
as	O
anti-static	O
conductive	O
film	O
,	O
around	O
a	O
standard	O
stylus	B-Device
or	O
rolling	O
the	O
film	O
into	O
a	O
tube	O
.	O
</s>
<s>
Capacitive	O
touchscreens	B-Device
are	O
more	O
expensive	O
to	O
manufacture	O
than	O
resistive	B-Device
touchscreens	I-Device
.	O
</s>
<s>
Mutual	O
capacitive	B-Device
sensors	I-Device
can	O
provide	O
a	O
two-dimensional	O
image	O
of	O
the	O
changes	O
in	O
the	O
electric	O
field	O
.	O
</s>
<s>
While	O
capacitive	B-Device
sensors	I-Device
are	O
used	O
for	O
the	O
touchscreens	B-Device
of	O
most	O
smartphones	O
,	O
the	O
capacitive	O
image	O
is	O
typically	O
not	O
exposed	O
to	O
the	O
application	O
layer	O
.	O
</s>
<s>
Many	O
stylus	B-Device
designs	O
for	O
resistive	B-Device
touchscreens	I-Device
will	O
not	O
register	O
on	O
capacitive	B-Device
sensors	I-Device
because	O
they	O
are	O
not	O
conductive	O
.	O
</s>
<s>
Styluses	O
that	O
work	O
on	O
capacitive	O
touchscreens	B-Device
primarily	O
designed	O
for	O
fingers	O
are	O
required	O
to	O
simulate	O
the	O
difference	O
in	O
dielectric	O
offered	O
by	O
a	O
human	O
finger	O
.	O
</s>
