What are biosensors?
• The IUPAC (1997) defines biosensors as: “A device that uses specific
biochemical reactions mediated by isolated
enzymes, immunosystems, tissues, organelles or whole cells to detect
chemical compounds usually by electrical, thermal or optical signals”.
• A biosensor according to IUPAC recommendations 1999, is an
independently integrated receptor transducer device, which is capable
of providing selective quantitative or semi-quantitative analytical
information using a biological recognition element.
What are biochips?
• In molecular biology, biochips are essentially miniaturized laboratories
that can perform hundreds or thousands of simultaneous biochemical
reactions. Biochips enable researchers to quickly screen large numbers
of biological analytes for a variety of purposes, from disease diagnosis
to detection of bioterrorism agents.
• One of the first commercial biochips was introduced by Affymetrix.
Their "GeneChip" products contain thousands of individual DNA
sensors for use in sensing defects.
Make-up of a typical biochip
Leland Clark published a paper on an oxygen sensing electrode (Clark, 1956_41).
This device became the basis for a glucose sensor
Guilbalt and Montalvo described the first potentiometric enzyme electrode, based on
the use of urease.
Yellow Spring Instrument Co. launched glucose biosensor
Biostator was invented
1st needle type enzyme electrode for subcutaneous implantation of glucose
biosensors is reported.
MediSense launched a pen-sized meter for home blood-glucose monitoring
Glass pH electrode, invented in 1922 by Hughes
• The biochip-transponder consists of four parts; computer microchip,
antenna coil, capacitor and the glass capsule.
• The transponder: The transponder is the actual biochip implant. It is a
passive transponder it contains no battery or energy of it's own. In
comparison, an active transponder would provide its own energy
source, normally a small battery. Because the passive biochip contains
no battery, or nothing to wear out, it has a very long life, up to 99 years,
and no maintenance overheads.
• Computer Microchip
– The microchip stores a unique identification number from 10 to 15 digits
long. The storage capacity of the current microchips is limited, capable of
storing only a single ID number. AVID (American Veterinary Identification
Devices), claims their chips, using a nnn-nnn-nnn format, has the
capability of over 70 trillion unique numbers. The unique ID number is
etched or encoded via a laser onto the surface of the microchip before
assembly. Once the number is 14 encoded it is impossible to alter. The
microchip also contains the electronic circuitry necessary to transmit the
ID number to the reader.
• Antenna Coil
– This is normally a simple, coil of copper wire around a ferrite or iron core.
This tiny, primitive, radio antenna receives and sends signals from the
reader or scanner.
• Tuning Capacitor
– The capacitor stores the small electrical charge (less than 1/1000 of a
watt) sent by the reader or scanner, which triggers the transponder. This
activation allows the transponder to send back the ID number encoded in
the computer chip. As radio waves are utilized to communicate between
the transponder and reader, the capacitor is tuned to the same frequency
as the reader.
• Glass Capsule
– The glass capsule holds the microchip, antenna coil and capacitor. It is a
small capsule, the smallest measuring 11 mm in length and 2 mm in
diameter, about the size of an uncooked grain of rice as shown in figure 2
and 3. The capsule is made of biocompatible material such as soda lime
glass. After assembly, the capsule is hermetically (air-tight) sealed, so no
bodily fluids can touch the electronics inside.
• The reader
– The reader consists of an "exciter" coil
which creates an electromagnetic field that,
via radio signals, provides the necessary
energy (less than 1/1000 of a watt) to
"excite" or "activate" the implanted biochip.
The reader also carries a receiving coil that
receives the transmitted code or ID number
sent back from the "activated" implanted
biochip. This all takes place very fast, in
milliseconds. The reader also contains the
software and components to decode the
received code and display the result in an
Communication works in
Electronic Product Code
Header - Tag version number
EPC Manager - Manufacturer ID
Object class - Manufacturer’s product ID
Serial Number - Unit ID
With 96 bit code, 268 million companies can each categorize 16 million different products where each product
category contains up to 687 billion individual units
Viability of the living cells is favored since the
"biochip" transistor does not need to heat up, as a
vacuum tube does, and it responds instantly.
It can operate on a tiny amount of power -- about
one tenth of that used by an ordinary flashlight
bulb and be locally modulated by biomembrane
potentials which can approach 1,000,000 volts/cm.
Biochips can be made almost vanishingly small.
The present experimental crystal adducts of
germanium and bacteria produced by us are only
about 5 micrometers on a side.
The ability to detect multiple viral agents in
Increase speed of diagnosis of unknown pathogens
("future proofed" surveillance tools).
Miniaturization: Biochips are extremely small in
size. The following figure gives an idea about its
• These methods have problems that a DNA chip cannot be fabricated at high
density and mass production is limited.
• The Lock: A chip implant would contain a person’s financial world, medical
history, health care — it would contain his electronic life". If cash no longer
existed and if the world’s economy was totally chip oriented; — there would be
a huge "black-market" for chips! Since there is no cash and no other bartering
system, criminals would cut off hands and heads, stealing "rich-folks" chips.
• A key challenge to the biochip industry is standardization. Both the assays and
the ancillary instrumentation need to be interfaced so that the data can be
easily integrated into existing equipment..
• Genomics is the study of
gene sequences in living
organisms and being
interpret them. The
human genome has been
undertaken to date but
there are many research
projects around the
world trying to map the
gene sequences of other
investigation of all the
proteins present in a cell,
tissue or organism.
• The use of Biochip
– High throughput proteomic
LC/MS) to achieve high
• Every living creature
is made up of cells, the
basic building blocks
of life. Cells are used
widely by for several
study of drug cell
interactions for drug
discovery, as well as in
• Biodiagnostics or
biosensing is the field of
molecules based on
The use of biochip
facilitates development of
sensors which involves
optimization of the
platform, reduction in
detection time and
improving the signal-tonoise ratio.
Biochip Technology –A Gigantic Innovation; Prof. T.Venkat Narayana Rao, Sai
Engineering, Hyderabad Institute of Technology; SSN 2250-2459, Volume 2, Issue
3, March 2012.
Biochip Technology and Applications; Mr. Chaithanya Kadari, Mr. Saidulu
Yalagandula, Miss. Padma Koutarapu; International Journal of Biometrics and
Bioinformatics (IJBB), Volume (5): Issue (2): May / June 2011.
Advances in biosensors: principle, architecture and applications; Veeradasan
Perumal, Uda Hashim Institute of Nano Electronic Engineering (INEE), University
Malaysia Perlis (UniMAP), Perlis, Malaysia.
The making of microarray; Peter Gwynne, Gary Heebner; DNA and BioChips
Invention of the
Biochip implantation - When humans get tagged; Renjith VP, SiliconIndia
Nature Biotechnology 18, IT43 - IT44 (2000); doi:10.1038/80082