Micro electro mechanical systems (MEMS) comprise a rapidly expanding
research field with potential applications varying from sensors
in air bags, wrist-warn GPS receivers, and matchbox size digital
cameras to more recent optical applications. Depending on the
application, these devices often require an on board power source
for remote operation, especially in cases requiring for an extended
period of time. In the quest to boost micro scale power generation
several groups have turn their efforts to well known enable sources,
namely hydrogen and hydrocarbon fuels such as propane, methane,
gasoline and diesel. Some groups are developing micro fuel cells
than, like their micro scale counter parts, consume hydrogen to
produce electricity. Others are developing on-chip combustion
engines, which actually burn a fuel like gasoline to drive a minuscule
electric generator. But all these approaches have some difficulties
regarding low energy densities, elimination of by products, down
scaling and recharging. All these difficulties can be overcome
up to a large extend by the use of nuclear micro batteries.
thermo electric generators (RTGs) exploited the extraordinary
potential of radioactive materials for generating electricity.
RTGs are particularly used for generating electricity in space
missions. It uses a process known as See-beck effect. The problem
with RTGs is that RTGs don’t scale down well. So the scientists
had to find some other ways of converting nuclear energy into
electric energy. They have succeeded by developing nuclear batteries.
            Nuclear batteries
use the incredible amount of energy released naturally by tiny
bits of radio active material without any fission or fusion taking
place inside the battery. These devices use thin radioactive films
that pack in energy at densities thousands of times greater than
those of lithium-ion batteries. Because of the high energy density
nuclear batteries are extremely small in size. Considering the
small size and shape of the battery the scientists who developed
that battery fancifully call it as “DAINTIEST DYNAMO”.
The word ‘dainty’ means pretty.
have developed two types of micro nuclear batteries. One is junction
type battery and the other is self-reciprocating cantilever. The
operations of both are explained below one by one.
           The kind
of nuclear batteries directly converts the high-energy particles
emitted by a radioactive source into an electric current. The
device consists of a small quantity of Ni-63 placed near an ordinary
silicon p-n junction – a diode, basically.

            As the Ni-63 decays it emits beta particles, which are high-energy
electrons that spontaneously fly out of the radioisotope’s unstable
nucleus. The emitted beta particles ionized the diode’s atoms,
exciting unpaired electrons and holes that are separated at the
vicinity of the p-n interface. These separated electrons and holes
streamed away form the junction, producing current.