CHARGING BATTERIES –APPLICATIONS OF PIEZOELECTRICITY

Shachi Raodeo TE E&TCMKSSS Cummins College Of Engineering for Women

PROBLEM STATEMENT Rechargeable batteries need to be kept full time charged

and to avoid the need of any consumable external energy source to charge the batteries

To reduce the hazards of traditional methods of energy generation and thus use natural deformations from different sources and convert them into electric charge by the use of piezoelectric effect

To power metal detectors with batteries rechargeable using piezoelectric phenomenon

SOLUTION

To lay down piezoelectric crystal strips at the footrests of metal detectors so that the pressure from footfalls can be converted into electric energy which can power the metal detector LED’s and buzzers

Alternate way to increase output voltage – amplification of the crystal o/p using high gain amplifiers (~around 6V and 1Amps)

Piezo Strips can also be placed in corridors, trains to power LED’S

TECHNOLOGY Piezoelectric crystal has a wurtzite structure stacked layer by

layer. Lack of central symmetry of this crystal results in piezoelectric effect (crystal possesses symmetry in strain free state , but on subject to force gets deformed and produces electric charges)

When the crystal is connected to external load the charge tends to flow out to counter balance this deformation. This voltage generated at the opposite edges of the crystal is AC and when passed through a rectifier gets converted into DC to be used by device

TECHNOLOGY Nano wires can also be used to generate alternating

current which work on principle similar to piezoelectric effect

A piezoelectric nano wire is based on laterally bonded nano version polymer substrate. If the length of nano wire used is 1.2um and 85nN force is applied at its ends then it produces a potential difference of 0.4V at its ends (without amplifier)

The voltage developed on amplification is sufficient to charge a battery

UNIQUE SELLING POINT

Cost effective - a single piezoelectric crystal costs less than 25 which makes the assembly cost very less. It is ₹possible to get sufficient voltage and current at a low cost

Durability - These piezoelectric nanostructures exhibit extremely high elasticity and resistance to fatigue due to the small size and single crystallinity, which are important for the lifetime of the devices

Combining energy from a number of piezoelectric crystals and connecting them in cascade can help to obtain higher in circuit voltages up to 3.5V and 0.1Amps

MARKET SIZE

According to reports the market size for piezoelectric devices is growing at a CAGR of 6%

Investments in piezoelectric devices is estimated to reach USD $27 billion by 2020

Market research reports suggest growth of 100 million piezoelectric units this year

*(Forecast by Markets And Markets)