Most of us won’t like the idea of implanting a biochip in our body that identifies us uniquely and can be used to track our location. That would be a major loss of privacy. But there is a flip side to this! Such biochips could help agencies to locate lost children, downed soldiers and wandering Alzheimer’s patients.
The human body is the next big target of chipmakers. It won’t be long before biochip implants will come to the rescue of sick, or those who are handicapped in someway. Large amount of money and research has already gone into this area of technology.
Anyway, such implants have already experimented with. A few US companies are selling both chips and their detectors. The chips are of size of an uncooked grain of rice, small enough to be injected under the skin using a syringe needle. They respond to a signal from the detector, held just a few feet away, by transmitting an identification number. This number is then compared with the database listings of register pets.
Daniel Man, a plastic surgeon in private practice in Florida, holds the patent on a more powerful device: a chip that would enable lost humans to be tracked by satellite.
A biochip is a collection of miniaturized test sites (micro arrays) arranged on a solid substrate that permits many tests to be performed at the same time in order to get higher throughput and speed. Typically, a biochip’s surface area is not longer than a fingernail. Like a computer chip that can perform millions of mathematical operation in one second, a biochip can perform thousands of biological operations, such as decoding genes, in a few seconds.
A genetic biochip is designed to “freeze” into place the structures of many short strands of DNA (deoxyribonucleic acid), the basic chemical instruction that determines the characteristics of an organism. Effectively, it is used as a kind of “test tube” for real chemical samples.
A specifically designed microscope can determine where the sample hybridized with DNA strands in the biochip. Biochips helped to dramatically increase the speed of the identification of the estimated 80,000 genes in human DNA, in the world wide research collaboration known as the Human Genome Project. The microchip is described as a sort of “word search” function that can quickly sequence DNA.
In addition to genetic applications, the biochip is being used in toxicological, protein, and biochemical research. Biochips can also be used to rapidly detect chemical agents used in biological warfare so that defensive measures can be taken. Motorola, Hitachi, IBM, Texas Instruments have entered into the biochip business.
STRUCTURE AND WORKING OF AN ALREADY IMPLANTED SYSTEM
The biochip implants system consists of two components: a transponder and a reader or scanner. The transponder is the actual biochip implant. The biochip system is radio frequency identification (RFID) system, using low-frequency radio signals to communicate between the biochip and reader. The reading range or activation range, between reader and biochip is small, normally between 2 and 12 inches.
3.1 The Transponder
The transponder is the actual biochip implant. It is a passive transponder, meaning it contains no battery or energy of its own. In comparison, an active transponder would provide its own energy source, normally a small battery.
Because the passive contains no battery, or nothing to wear out, it has a very long life up to 99 years, and no maintenance. Being passive, it is inactive until the reader activates it by sending it a low-power electrical charge.
The reader reads or scans the implanted biochip and receives back data (in this case an identification number) from the biochips. The communication between biochip and reader is via low-frequency radio waves.
Since the communication is via very low frequency radio waves it is nit at all harmful to the human body.
The biochip-transponder consists of four parts; computer microchip, antenna coil, capacitor and the glass capsule.
3.2 Computer Microchips
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 encoded it is impossible to alter. The microchip also contains the electronic circuitry necessary to transmit the ID number to the “reader”.
3.3 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.
3.4 Tuning Capacitor
The capacitor stores the small electrical charge (less than 1/1000 of a watt) sent by the reader or scanner, which activates the transponder. This “activation” allows the transponder to send back the ID number encoded in the computer chip. Because “radio waves” are utilized to communicate between the transponder and reader, the capacitor is tuned to the same frequency as the reader.
3.5 Glass Capsule
The glass capsule “houses” 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. 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. Because the glass is very smooth and susceptible to movement, a material such as a polypropylene polymer sheath is attached to one end of the capsule. This sheath provides a compatible surface which the boldly tissue fibers bond or interconnect, resulting in a permanent placement of the biochip.
The biochip is inserted into the subject with a hypodermic syringe. Injection is safe and simple, comparable to common vaccines. Anesthesia is not required nor recommended. In dogs and cats, the biochip is usually injected behind the neck between the shoulder blades.
3.6 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 LCD display. The reader can include a RS-232 port to attach a computer.
Biochips are not cheap, though the price is falling rapidly. A year ago, human biochips cost $2,000 per unit. Currently human biochips cost $1,000, while chips for mice, yeast, and fruit flies cost around $400 to $500. The price for human biochips will probably drop to $500 this year. Once all the human genes are well characterized and all functional human SNPs are known, manufacture of the chips could conceivably be standardized. Then, prices for biochips, like the prices for computer memory chips, would fall through the floor.
The reader generates a low-power, electromagnetic field, in this case via radio signals, which “activates” the implanted biochip. This “activation” enables the biochip to send the ID code back to the reader via radio signals. The reader amplifies the received code, converts it to digital format, decodes and displays the ID number on the reader’s LCD display. The reader must normally be between 2 and 12 inches near the biochip to communicate. The reader and biochip can communicate through most materials, except metal.
APPLICATIONS OF BIOCHIP
Genomics is the study of gene sequences in living organisms and being able to read and interpret them. The human genome has been the biggest project undertaken to date but there are many research projects around the world trying to map the gene sequences of other organisms. The use of Biochip facilitate: Automated genomic analysis including genotyping, gene expression DNA isolation from complex matrices with aim to increase recovery efficiency DNA amplification by optimizing the copy numberDNA hybridization assays to improve speed and stringency .
Proteome analysis or Proteomics is the investigation of all the proteins present in a cell, tissue or organism. Proteins, which are responsible for all biochemical work within a cell, are often the targets for development of new drugs. The use of Biochip facilitate:
l High throughput proteomic
microseparations (pre LC/MS) to achieve high plate number
l Electrokinetic sample injection
for fast, reproducible, samples
l Stacking or other
preconcentration methods (as a precursor to biosensors) to improve
l Kinetic analysis of
interactions between proteins to enable accurate, transport-free kinetics
Every living creature is made up of cells, the basic building blocks of life.. Cells are used widely by for several applications including study of drug cell interactions for drug discovery, as well as in biosensing. The use of Biochip facilitate:
Biochip /Applications of Biochip
"lab-in-cell" platforms handling single or few cells with nanoprobes in carefully controlledenvironments.
l Cell handling, which involve
sorting and positioning of the cells optimally using DEP, optical traps
l Field/reagent based cell lysis,
where the contents of the cell are expelled out by breaking the membrane,
or increase the efficiency of transfection using reagents/field
l Intracellular processes to obtain
high quality safety/toxicity ADME/T data
4.4 Biodiagnostics and (Nano) Biosensors
Biodiagnostics or biosensing is the field of sensing biological molecules based on electrochemical, biochemical, optical, luminometric methods. The use of Biochip facilitate: Genetic/Biomarker Diagnostics, development of Biowarfare sensors which involves optimization of the platform, reduction in detection time and improving the signal-to-noise ratio
l Selection of detection platform where different formats such as lateral flow vs. microfluidics are compared for ease/efficiency. Incorporation of suitablesensing modality by evaluating tradeoffs and downselect detection modes(color / luminometric, electrochemical, biochemical, optical methods) forspecific need.
4.5 Protein Chips for Diagnosis and Analysis of Diseases
The Protein chip is a micro-chip with its surface modified to detect various disease causing proteins simultaneously in order to help find a cure for them. Bio-chemical materials such as antibodies responding to proteins, receptors, and nucleic acids are to be fixed to separate and analyze protein.
4.6 Biochips can detect cancers before symptoms develop
In their fight against cancer, doctors have just gained an impressive new weapon to add to their arsenal. Researchers at the U.S. Department of Energy's Argonne
National Laboratory have developed a chip that can save lives by diagnosing certain cancers even before patients become symptomatic.
The new technology, known as a biochip, consists of a one-centimeter by one centimeter array that comprises anywhere between several dozen and several hundred "dots," or small drops. Each of these drops contains a unique protein, antibody or nucleic acid that will attach to a particular DNA sequence or antigen.
A tumor, even in its earliest asymptomatic phases, can slough off proteins that find their way into a patient's circulatory system. These proteins trigger the immune system to kick into gear, producing antibodies that regulate which proteins belong and which do not.
"Antibodies are the guardians of what goes on in the body," said Tim Barder, president of Eprogen, Inc., which has licensed Argonne's biochip technology to search for new biomarkers that indicate cancer. "If a cancer cell produces aberrant proteins, then it's very likely that the patient will have an antibody profile that differs from that of a healthy person. You can look for similarities and differences in autoantibody profiles to look for clues and markers that provide early indicators of disease."
In their hunt for cancer indicators, Eprogen uses a process called 2-dimesional protein fractionation, which sorts thousands of different proteins from cancer cells by both their electrical charge and their hydrophobicity or "stickiness."
The 2-D fractionation process creates 960 separate protein fractions, which are then arranged in a single biochip containing 96-well grids. Eprogen scientists then probe the microarrays with known serum or plasma "auto-antibodies" produced by the immune systems of cancer patients.
By using cancer patients' own auto-antibodies as a diagnostic tool, doctors could potentially tailor treatments based on their personal autoantibody profile. "This technology is really designed to take advantage of the information contained within the patient's own biology," Barder said. "What makes this technique unique is that scientists can use the actual expression of the patient's disease as a means of obtaining new and better diagnostic information that doctors could use to understand and fight cancer better.
Biochips contain grids of small wells or “dots”,each of which contains a protein,antibody or nucleic acid that can bind to a target antigen or DNA sequence
BIOCHIPS CURRENTLY UNDER DEVELOPMENT
1. Chips that follow footsteps
2. Glucose level detectors
3. Oxy sensors
4. Brain surgery with an on-off switch
5. Adding sound to life
6. Experiments with lost sight
5.1 Chips that follow footsteps
The civil liberties debate over biochips has obscured their more ethically benign and medically useful applications. Medical researchers have been working to integrate chips and people for many years, often plucking devices from well known electronic appliances. Jeffry Hausdorff of the Beth Israel Deaconess Medical Center in Boston has used the type of pressure sensitive resistors found in the buttons of a microwave oven as stride timers. He places one sensor in the heel of a shoe, and one in the toe, adds a computer to the ankle to calculate the duration of each stride.
“Young, healthy subjects can regulate the duration of each step very accurately,” he says. But elderly patients prone to frequent falls have extremely variable stride times, a flag that could indicate the need for more strengthening exercises or a change in medication. Hausdorff is also using the system to determine the success of a treatment for congestive heart failure. By monitoring the number of strides that a person takes, can directly measure the patient’s activity level, bypassing the often-flowed estimate made by the patient.
5.2 Glucose level detectors
Diabetics currently use a skin prick and a handheld blood test, and then medicate themselves with the required amount of insulin. The system is simple and works well, but the need to draw blood means that most diabetics do not test themselves as often as they should. The new S4MS chip will simply sit under the skin, sense the glucose level, and send the result back out by radio frequency communication.
A light emitting diode starts off the detection process. The light that it produces hits a fluorescent chemical: one that absorbs the incoming light and re-emits it at a longer wavelength. The longer wavelength of light is detected, and the result is send to a control panel outside the body. Glucose is detected because the sugar reduces the amount of light that a fluorescent chemical re-emits. The more glucose is there the less light that is detected.
S4MS is still developing the perfect fluorescent chemical, but the key design innovation of the S4MS chip has been fully worked out. The idea is simple: the LED is sitting in a sea of fluorescent molecules. In most detectors the light source is far away from the fluorescent molecules, and the inefficiencies that come with that mean more power and larger devices. The prototype S4MS chip uses a 22 microwatt LED, almost forty times less powerful than a tiny power-on buttons on a computer keyboard. The low power requirements mean that energy can be supplied from outside, by a process called induction. The fluorescent detection itself does not consume any chemicals or proteins, so the device is self sustaining.
5.3 Oxy Sensors:
A working model of an oxy sensor uses the same layout. With its current circuitry, it is about the size of a large shirt button but the final silicon wafer will be less than a millimeter square. The oxygen sensors will be useful not only to monitor breathing inside intensive care units, but also to check that packages of food, or containers of semiconductors stored under nitrogen gas remain airtight.
Another version of an oxygen sensing chip currently under development sends light pulses out into the body. The light absorbed to varying extends, depending on how much oxygen is carried in the blood, and this chip detects the light that is left. The rushes of blood pumped by the heart are also detected, so the same chip is a pulse monitor. A number of companies already make large scale versions of such detectors.
The transition of certain semiconductors to their conducting state is inherently sensitive to temperature, so designing the sensor was simple enough.
With some miniature radio frequency transmitters, and foam-rubber earplugs to hold the chip in place, the device is complete. Applications range from sick children, to chemotherapy patients who can be plagued by sudden rises in body temperature in response to their anti-cancer drugs.
5.4 Brain surgery with an on-off switch:
Sensing and measuring is one thing, but can we switch the body on and off? Heart pacemakers use the crude approach: large jolts of electricity to synchronize the pumping of the heart. The electric pulses of Activa implant, made by US-based Medtronics Inc., are directed not at the heart but at the brain. They turn off brain signals that cause the uncontrolled movements, or tremors, associated with disease such as Parkinson’s.
Drug therapy of Parkinson’s disease aims to replace the brain messenger dopamine, a product of brain cells that are dying. But eventually the drug’s effects wear off, and the erratic movements come charging back.The Activa implant is a new alternative that uses high-frequency electric pulses to reversibly shut off the thalamus.
The implantation surgery is far less traumatic than thalamatomy, and if there are any post-operative problems the stimulator can simply be turned off. The implant primarily interferes with aberrant brain functioning.
5.5 Adding sound to life
The most ambitious bioengineers are today trying to add back brain functions, restoring sight and sound where there was darkness and silence. The success story in this field is the cochlear implant. Most hearing aids are glorified amplifiers, but the cochlear implant is for patients who have lost the hair cells that detect sound waves. For these patients no amount of amplification is enough.
The cochlear implant delivers electrical pulses directly to the nerve cells in the cochlea, the spiral-shaped structure that translates sound in to nerve pulses. In normal hearing individuals, sound waves set up vibrations in the walls of the cochlea, and hair cells detect these vibrations. High-frequency notes vibrate nearer the base of cochlea, while low frequency notes nearer the top of the spiral. The implant mimics the job of the hair cells. It splits the incoming noises into a number of channels (typically eight) and then stimulates the appropriate part of the cochlea.
5.6 Experiments with lost sight
With the ear at least partially conquered, the next logical target is the eye. Several groups are working on the implantable chips that mimic the action of photoreceptors, the light-sensing cells at the back of the eye. Photoreceptors are lost in retinitis pigmentosa, a genetic disease and in age related macular degeneration, the most common reason for loss sight in the developed world. Joseph Rizzo of the Massachusetts Eye and Ear Infirmary, and John Wyatt of Massachusetts Institute of Technology have made a twenty electrode 1mm-square chip, and implanted it at the back of rabbit’s eyes.
The original chip, with the thickness of human hair, put too much stress on the eye, so the new version is ten times thinner. The final setup will include a fancy camera mounted a pair of glasses. The camera will detect and encode the scene, then send it into the eye as a laser pulse, with the laser also providing the energy to drive the chip.
Rizzo has conformed that his tiny array of light receivers (photodiodes) can generate enough electricity needed to run the chip. He has also found that the amount of electricity needed to fire a nerve cell into action is 100-fold lower than in the ear, so the currents can be smaller, and the electrodes more closely spaced.
For now the power supply comes from a wire inserted directly in the eye and, using this device, signals reaches the brain.
Eugene de Jaun of Hopkins Wilmer Eye Institute is trying electrodes, electrodes inserted directly in to the eyes, are large and somewhat crude. But his result has been startling. Completely blind patients have seen well-defined flashes, which change in position and brightness as de Jaun changes the position of the electrode or amount of
THE AGILENT 2100 BIOANALYZER
The Agilent 2100 bioanalyzer is the industry’s only platform with the ability to analyze DNA, RNA, proteins and cells. Through lab-on-a-chip technology the 2100 bioanalyzer integrates sample handling, separation, detection and data analysis onto one platform. It moves labs beyond messy, time consuming gel preparation and the subjective results associated with electrophoresis. And now, with our second generation 2100 bioanalyzer, we have integrated an easier way to acquire cell based parameters from as few as 20,000 cells per sample.
The process is simple: load sample, run analysis, and view data. The 2100 bioanalyzer is designed to streamline the processes of RNA isolation, gene expression analysis, protein expression, protein purification and more. One platform for entire workflow!
BIOCHIPS IN NONINFECTIOUS DISEASES
7.1 Biochips and Proteomics
Biochip technology was largely established by the development of micro array biochips for genomics research. The emergence of the biochip was perhaps an inevitable development, an expansion of existing chemistries and concepts into the information rich world of genomics. The GeneChip, developed at Affymax, remains the best known example of a biochip.
The essential property of a biochip is the use of solid phase support and interfacial chemistry to capture molecules from a sample and present them for analysis. The use of a solid support provides the separation and isolation of an analyst, and creates the opportunity for high density micro arrays of sampling sites. Combined with scalable production techniques, often borrowed from semiconductor fabrication, it also offers the potential of high sample throughput. There are no absolute restriction on the types of molecules that can be analyzed using a biochip, only technical problems related to binding, retention and assay.
With the maturing of genomics, some limitations of genome-based research have become apparent. Although extremely useful, characterization of a cell based upon its genes or gene transcripts is only an indirect view. From an engineering perspective, the complete state of cell might be defined by its molecular composition. While this includes DND, RNA, small molecules, and ions, this state is defined by proteins and peptides. Consequently, proteomics, the systems level study of proteins, represents a direct view of the state of a cell and its parent organism. With some abstraction, in clinical practice the protein profile obtained from a biological sample may be seen as synonymous to the phenotype and overall health state of a patient.
7.2 SELDI Protein Biochips
A major challenge in molecular biology, and particularly biochip development, is the detection of analytics present in mixtures at extremely low concentrations. Mixtures create limitations for the optical detection methods typically used with biochips, while low concentrations present problems when traditional separation techniques, such as 2-D electrophoresis, are applied.
Surface Enhanced Laser Desorption Ionization Time-of-Flight Mass Spectroscopy (SELDI-TOF MS) was developed in the last decade as a powerful tool for overcoming these limitations, and is now being commercialized by several companies.
With a SELDI protein biochip, proteins are captured at a target site using techniques that are similar to traditional chromatographic techniques, the analysis of the biochips, however, is quite different. Instead of optical detection, the bound proteins are combined with a charge and energy transfer molecule and assayed using laser desorption ionization time-of-flight mass spectroscopy. With TOF MS, it becomes possible to simultaneously identify hundreds or thousands of proteins and peptides bound to a single site. TOF MS is also capable of detecting analytes present in nanomole to sub-femtomole quantities, corresponding to millimolar to Pico molar concentrations in a typical biological sample. Because of these capabilities, SELDI biochip surfaces can be prepared with diverse chemistries that have varying degrees of protein-binding specificity, and their selectivity may be further enhanced through variations in protein capture and retention protocols.
7.3 Bioinformatics with SELDI Biochips
In practice, the SELDI-TOF technique provides mass spectra of proteins unmatched in both its sensitivity and its ability to identify hundreds of proteins simultaneously. A collection of protein mass spectra can be obtained from diverse biochip surfaces, using varied protein binding protocols, creating a protein map. The information in this protein map combines protein molecular weight with chemical knowledge derived from the protein binding interactions at the biochip surface.
Protein maps are rich descriptions of the biological sample, which characterize the psychological state of a patient. Their information destiny and complexity often defies simpler linear analysis. In order to best utilize this data, LumiCyte has developed software that incorporates the latest techniques for data base mining, pattern recognition, and artificial intelligence. Some of the challenges include managing large volume data sets, searching for reproducible patters in data, which has variable alignment and instrument artifacts, and dealing with the inherent variability present in biological samples. Classification and analysis methods that have been successful include both trained artificial intelligence tools, such as support vector machines and genetic algorithms, as well as unsupervised cluster analysis.
Applying these tools to the differential analysis of protein maps rapidly uncovers the extent and nature of protein variations. This analysis can be applied to samples from multiple patients of differing phenotypes, where it leads to early detection of disease, even in asymptomatic patients. It also provides a powerful tool for discriminating between physiologically distinct diseases that present similar or even identical symptoms. With samples from a single patient, analysis of protein maps reveals early onset of disease, disease progression, and the patient’s response to therapy.
7.4 Challenges of protein biochips
A number of challenges remain that define the current boundaries of SELDI biochip technology. For physical scientists, the optimization of surfaces that capture and present proteins is an ongoing activity, and the development of TOF MS for detection over an even wider dynamic range is essential to find rare, important proteins in the presence of ubiquitous, common proteins. For biological scientists, sequencing proteins that are discovered with SELDI-TOF MS and interpreting the complex network of revealed proteins are tasks that expand with every new sample set.
For applied mathematicians and software engineers, creating new pattern recognition tools is important as we attempt to identify weaker and weaker signals in the protein map capture.
ADVANTAGES & DISADVANTAGES
- The ability to detect multiple viral agents in parallel e.g. differential diagnosis of agents from other diseases that cause similar clinical symptoms, or the recognition of complex mixtures of agents. .Clarification of syndromes of unknown aetiology .Increase speed of diagnosis of unknown pathogens ("future proofed" surveillance tools).
- Viral typing (AIV, FMDV, Rabies)
- Drive policy for diagnostics and disease control.
- Epidemiological tracing.
- Interagency collaboration.
- The consortium consists of National, EU and OIE reference laboratories and has access to real sample material from a wide selection of hosts and viruses.
· These methods have problems that a DNA chip cannot be fabricated at high density and mass production is limited. Thus, these methods are applicable to fabrication of a DNA chip for study.
· Meanwhile, the DNA chip and the DNA microarray have different fabrication methods but are similar in that different oligonucleotides are aligned on a square spot having a certain size in a check pattern.
HUMAN INTERFACE TO BIOCHIP
Biochips provide interfaces between living systems and electro-mechanical and computational devices. These chips may be used in such varied applications as artificial sensors, prosthesis, portable/disposable laboratories or even as implantable devices to enhance human life. Biochips promise dramatic changes in future medical science and human life in general. With the advances of bio and nano technologies two strong paradigms of integrated electronic and life are emerging. Biosensor chips can provide the construction of sophisticated human sensing systems such as nose and ears. The second paradigm is chips for sensing biology that will provide for interactions with living bodies and build new diagnosis tools (such as diabetes glucose meters) or new medicines (such as a bio-assay chip). A tiny microchip, the size of a grain of rice, is simply placed under the skin. It is so designed as to be injected simultaneously with a vaccination or alone."
The biochip is inserted into the subject with a hypodermic syringe. Injection is safe and simple, comparable to common vaccines. Anesthesia is not required nor recommended. In dogs and cats, the biochip is usually injected behind the neck between the shoulder blades. Trovan, Ltd., markets an implant, featuring a patented "zip quill", which you simply press in, no syringe is needed. According to AVID "Once implanted, the identity tag is virtually impossible to retrieve. . . The number can never be altered."
A new DNA biochip developed by Tuan Vo-Dinh and colleagues at the Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) could revolutionize the way the medical profession performs tests on blood. Instead of patient having to wait several days for the results form a laboratory, they are virtually immediate with the matchbox-sized biochip. And it requires less blood with no sacrifice on accuracy.
In addition to time savings, the DNA biochip eliminates the needs for radioactive labels used for detection. This greatly reduces cost and potential health effects to technicians and lab workers handling samples and performing tests. It also reduces disposal costs because chemically labeled blood must be handled according to strict regulations.
To be useful for detecting compounds in a real-life sample, a biosensor must be extremely sensitive and able to distinguish between, for example, a bacteria, virus or chemical or biological species. ORNL’s DNA biochip does that.
Unlike other biosensors based on enzyme and antibody probes, The DNA biochip is a gene probe-based biosensor.
Within ten years you will have a biochip implanted in your head consisting of financial status, employment and medical records.
Even in a grocery store, sensor will read the credit chip and will automatically debit the account for purchase.
A biochip implanted in our body can serve as a combination of credit ca5rd, passport, driver’s license and personal diary. And there is nothing to worry about losing them.
It is said that by 2008, all members of typical American family including there pets will have microchips under their skin with ID and medical data.
 K. E. Petersen, W. A. McMillan, G. T. A. Kovacs, M. A. Northrup, L. A. Christel, and F. Pourahmadi, "Toward next generation clinical diagnostic instruments: scaling and new processing paradigms," Journal of Biomedical Microdevices 1,pp. 71-79, 1998.
 R. E. Kunz, "Miniature integrated optical modules for chemical and biochemical sensing," Sensors and Actuators B 38-39, pp. 13-28, 1997.
http://en.wikipedia.org/wiki/components of biochip