What is so special about SQUID (Superconducting Quantum Interference Device)?Dec 05, 2014
SQUID was an
accidental discovery in the Ford Motor Company’s research lab in Dearborn,
Michigan. Five Researchers John Lambe, James Zimmerman, Arnold Silver, Robert
Jaklevic, and James Mercereau made this vital discovery in superconductivity.
They found, when cooling the SQUID a few degrees above absolute zero, it can
detect a magnetic field that is less than 5 quintillionths of a tesla.
research was performed for gaining knowledge rather than for Ford’s commercial
requirements. In 1963, the group discovered the Josephson Effect in a sample of
super-cooled phosphorous-doped silicon. There are two main types of SQUIDS – Direct
Current (DC) and Radio Frequency (RF).
SQUID is otherwise
known as Superconducting Interferometers and they come in all sizes and shapes. With the growing technological advancement, these
devices have considerably shrunk in size. Now there are nano squids which are
compact unlike the earlier version which stretched across many kilometers. Nano
Squid are a type of SQUID made out of carbon nanotubes which is just one
nanometer in diameter. This SQUID is powerful enough to detect magnetic changes
even in a molecule.
SQUIDS work by splitting a wave into two components and sending them along
different paths. These waves are recombined to find out if any of the waves has
encountered any strange obstruction or interference. The phase of the two waves
are checked. If both of them have travelled the same distance then the phase
remains the same for both the waves. But if one of the waves encountered an
obstruction then the phase changes. The details about the
obstruction can be found out by measuring the phase difference between the two
Since the SQUID is
able to detect such small levels of magnetic field it is used in a variety of
ways such as:
- Traditional and
- Detection of the
cosmic microwave background
- Geophysical and
- Imaging the brain,
heart, and other body parts
testing of materials and devices
These devices are
effective in places where machinery cannot be taken apart to find out its wear
and tear. In such instances, these SQUID devices help to detect the
depreciation value of the working equipment. Moreover, the information gathered
from these devices helps service engineers to take the corrective steps for
ensuring the machines working condition, within the safety rules.
In the medical
field, these devices have proven to be helpful in an exemplary way for the
physicians. The usage of SQUID in Magneto Encephalography field is a good
example of that. An array of squids are used to study neural activity inside
the brain. Likewise, Magnetogastrography measures functions of the stomach. Drugs
maybe orally applied and the instrument will trace the path of the drug to find
out the function of the stomach. In such scenarios the Magnetic Marker
Monitoring method is used.
SQUIDS are very
commonly used in Magnetic Property Measuring Systems. The magnetic property of
any material can be measured when the temperature range of 300 K - 400 K is
maintained for these operations.
innumerable uses and recent innovative research has proven these priceless
devices to be a powerful help in various fields. SQUID falls under the
electromagnetic interference topic which is a deeper look at the
Electromagnetics section on the Electrical FE Exam.