<s>
Betacel	B-Algorithm
is	O
considered	O
to	O
be	O
the	O
first	O
commercially	O
successful	O
betavoltaic	B-Algorithm
battery	I-Algorithm
.	O
</s>
<s>
This	O
power	O
source	O
was	O
incorporated	O
in	O
the	O
Betacel-Biotronik	O
heart	B-Device
pacemaker	I-Device
.	O
</s>
<s>
The	O
betavoltaic	B-Algorithm
program	O
along	O
with	O
the	O
development	O
of	O
the	O
Betacel	B-Algorithm
was	O
led	O
by	O
Dr.	O
Olsen	O
and	O
a	O
team	O
of	O
researchers	O
at	O
Donald	O
W	O
.	O
Douglas	O
Laboratories	O
(	O
DWDL	O
)	O
,	O
McDonnell	O
Douglas	O
Corporation	O
,	O
in	O
the	O
early	O
1970s	O
.	O
</s>
<s>
As	O
the	O
first	O
(	O
and	O
only	O
)	O
viable	O
betavoltaic	B-Algorithm
power	O
source	O
ever	O
developed	O
,	O
it	O
was	O
immediately	O
used	O
to	O
power	O
heart	B-Device
pacemakers	I-Device
.	O
</s>
<s>
Betacel	B-Algorithm
powered	O
cardiac	O
pacemakers	B-Device
were	O
implanted	O
in	O
numerous	O
patients	O
in	O
the	O
1970s	O
.	O
</s>
<s>
Biotronik	O
GmbH	O
&	O
Co.	O
,	O
Ingenieurburo	O
,	O
Berlin	O
,	O
adapted	O
its	O
chemical	O
battery-powered	O
pacemakers	B-Device
to	O
accept	O
the	O
promethium-fueled	O
Betacel	B-Algorithm
battery	O
.	O
</s>
<s>
The	O
Betacel	B-Algorithm
powered	O
Biotronik	O
pacemakers	B-Device
were	O
considered	O
to	O
have	O
useful	O
lives	O
of	O
7	O
to	O
10	O
years	O
.	O
</s>
<s>
Clinical	O
investigation	O
of	O
the	O
Betacel-Biotronik	O
pacemaker	B-Device
began	O
in	O
Europe	O
in	O
1972	O
and	O
was	O
extended	O
to	O
the	O
United	O
States	O
under	O
State	O
of	O
Washington	O
license	O
in	O
1973	O
.	O
</s>
<s>
By	O
early	O
1973	O
,	O
over	O
60	O
implanted	O
Betacel-Biotronik	O
pacemakers	B-Device
were	O
being	O
monitored	O
as	O
part	O
of	O
the	O
clinical	O
investigation	O
.	O
</s>
<s>
By	O
mid-1974	O
,	O
the	O
USAEC	O
had	O
authorized	O
the	O
licensing	O
in	O
the	O
United	O
States	O
of	O
a	O
Clinical	O
Investigation	O
Program	O
that	O
allowed	O
the	O
implantation	O
of	O
50	O
Betacel-Biotronik	O
pacemakers	B-Device
per	O
month	O
in	O
major	O
clinics	O
in	O
the	O
U.S.	O
</s>
<s>
Betacels	B-Algorithm
utilized	O
Pm-147	O
beta	O
sources	O
that	O
were	O
combined	O
with	O
custom	O
designed	O
silicon	O
p-n	O
junctions	O
.	O
</s>
<s>
The	O
power	O
output	O
of	O
the	O
Betacel	B-Algorithm
was	O
approximately	O
400	O
microWatts	O
.	O
</s>
<s>
These	O
Betacel	B-Algorithm
batteries	O
presented	O
an	O
efficiency	O
of	O
approximately	O
4%	O
.	O
</s>
<s>
Unfortunately	O
,	O
these	O
higher	O
efficiency	O
devices	O
were	O
never	O
realized	O
since	O
pacemaker	B-Device
manufacturers	O
focused	O
on	O
the	O
use	O
of	O
lithium-ion	O
batteries	O
which	O
did	O
not	O
utilize	O
radioactive	O
material	O
,	O
and	O
could	O
power	O
pacemakers	B-Device
for	O
5	O
to	O
7	O
years	O
.	O
</s>
<s>
Although	O
previous	O
betavoltaic	B-Algorithm
devices	I-Algorithm
degraded	O
rapidly	O
due	O
to	O
radiation	O
damage	O
,	O
the	O
Betacel	B-Algorithm
showed	O
no	O
deleterious	O
effects	O
from	O
radiation	O
.	O
</s>
<s>
In	O
particular	O
,	O
the	O
battery	O
power	O
decreased	O
exponentially	O
with	O
a	O
half-life	B-Application
of	O
2.62	O
years	O
,	O
the	O
same	O
as	O
that	O
for	O
Pm-147	O
.	O
</s>
<s>
Pm-147	O
is	O
not	O
an	O
ideal	O
source	O
since	O
the	O
half	B-Application
life	I-Application
is	O
only	O
2.62	O
years	O
and	O
the	O
contaminant	O
Pm-146	O
emits	O
gamma	O
rays	O
that	O
require	O
batteries	O
to	O
be	O
well	O
shielded	O
.	O
</s>
<s>
This	O
stigma	O
,	O
combined	O
with	O
advances	O
in	O
(	O
and	O
the	O
lower	O
cost	O
of	O
)	O
lithium-ion	O
battery	O
technology	O
,	O
eventually	O
overshadowed	O
aspirations	O
of	O
a	O
more	O
lucrative	O
future	O
for	O
the	O
Betacel	B-Algorithm
,	O
relegating	O
betavoltaic	B-Algorithm
batteries	O
to	O
the	O
realm	O
of	O
academic	O
research	O
in	O
the	O
years	O
that	O
immediately	O
followed	O
.	O
</s>
<s>
The	O
Betacel	B-Algorithm
did	O
not	O
last	O
but	O
it	O
provided	O
a	O
foundation	O
for	O
future	O
betavoltaic	B-Algorithm
technology	O
research	O
and	O
sparked	O
a	O
resurgence	O
of	O
interest	O
in	O
betavoltaic	B-Algorithm
power	O
generation	O
.	O
</s>
<s>
Other	O
sources	O
such	O
as	O
tritium	B-Language
have	O
been	O
considered	O
and	O
implemented	O
in	O
the	O
development	O
of	O
betavoltaic	B-Algorithm
batteries	O
.	O
</s>
<s>
Between	O
2001	O
and	O
2010	O
,	O
four	O
commercial	O
companies	O
(	O
City	O
Labs	O
,	O
Inc.	O
,	O
BetaBatt	O
Inc.	O
,	O
Qynergy	O
,	O
Inc	O
.	O
and	O
Widetronix	O
,	O
Inc	O
.	O
)	O
have	O
ventured	O
into	O
betavoltaic	B-Algorithm
power	O
cell	O
development	O
,	O
while	O
university	O
research	O
on	O
the	O
subject	O
is	O
still	O
actively	O
being	O
conducted	O
.	O
</s>
<s>
Rapid	O
advances	O
in	O
semiconductor	O
and	O
materials	O
science	O
technology	O
,	O
integrated	O
circuit	O
design	O
and	O
fabrication	O
,	O
and	O
micro	O
-	O
/	O
nano-scale	O
microelectromechanical	B-Architecture
systems	I-Architecture
(	O
MEMS	B-Architecture
)	O
,	O
have	O
converged	O
to	O
the	O
extent	O
that	O
extremely	O
small	O
devices	O
with	O
diminutive	O
power	O
requirements	O
are	O
becoming	O
more	O
and	O
more	O
routine	O
.	O
</s>
<s>
These	O
devices	O
are	O
ideally	O
suited	O
for	O
betavoltaic	B-Algorithm
power	O
sources	O
that	O
can	O
easily	O
and	O
safely	O
offer	O
nanoWatt-to-microWatt	O
power	O
levels	O
with	O
enduring	O
20-year	O
lifetimes	O
.	O
</s>
