16-02-2011, 11:12 AM
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BIOCHIPS
Biochips were invented 9 years ago by gene scientist Stephen Fodor . In a flash of light he saw that photolithography, the process used to etch semi conductor circuits in to silicon could also be used to assemble particular DNA molecules on a chip.
The human body is the next biggest target of chip makers . medical researchers have been working since a long period to integrate humans body and chips . In no time or at maximum within a short period of time Biochips can get implanted into the body of humans . So integration of humans and chips is achieved this way .
Money and research has already gone into this area of technology .Anyway such implants are already being experimented with animals . A
simple chip is being is being implanted into tens of thousands of animals especially pets.
DEFINITION:-
A biochip is a collection of miniaturized test sites (microarrays)
Arranged on a solid substrate that permits many tests to be performed
At the same time inorder to achieve higher throughput and speed .
Typically a biochips surface is no larger than a finger nail . Like
A computer chip that can perform millions of mathematical operations
In one second , a biochip can perform thousands of biological reactions
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 ( deoxyribo nucleic acid ) , the basic chemical instruction that determines the characterstics of an organism . effectively , it is used as a kind of “ test tube “ for real chemical samples. A specially designed microscope can determine where the sample hybridised with DNA strands in the biochip.
IN WHAT WAY THEY WORK:-
The chips are of the 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 a database listing of registered pets .
GETTING UNDER THE SKIN :-
Hausdorffs chips are external , but another chip currently under development will be injected under skin . The chips will allow diabetics to monitor the level of sugar glucose in their blood . Diabetics currently use a skin prick and a handheld blood test and then medicate themselves with insulin , depending on the result . The system is simple and works well , but drawing blood each time is pain full so patients donot test themselves as often as it is needed
THE S4MS CHIP:-
The new s4ms chip will get underneath the skin sense the glucose level and send the result back by radio frequency communication. A light emitting diode starts of the detection process . The light that it produces hits a fluorescent chemical : one that absorbs incoming light and re emits it at a longer wavelength . The longer wavelength of light is then detected , and the result is sent to a control panel outside the body . Glucose is detected, because the sugar reduces the amount of light that the florescent chemical re emits . the more glucose there is 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 the 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 22W LED, almost 40 times less powerful than the tiny power on buttons on a computer keyboard. The low power requirements mean that energy can be supplied from the outside, by the process called induction. The fluorescent detection itself does not consume any chemicals or proteins, so the device is self – sustaining
THE S4MS CHIP:-
The new s4ms chip will get underneath the skin sense the glucose level and send the result back by radio frequency communication. A light emitting diode starts of the detection process . The light that it produces hits a fluorescent chemical : one that absorbs incoming light and re emits it at a longer wavelength . The longer wavelength of light is then detected , and the result is sent to a control panel outside the body . Glucose is detected, because the sugar reduces the amount of light that the florescent chemical re emits . the more glucose there is 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 the 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 22W LED, almost 40 times less powerful than the tiny power on buttons on a computer keyboard. The low power requirements mean that energy can be supplied from the outside, by the process called induction. The fluorescent detection itself does not consume any chemicals or proteins, so the device is self – sustaining
BIOCHIPS USED TO DETECT AND MONITOR DISEASES:-
CHIPS THAT FOLLOW FOOT STEPS : -
The civil debate over biochips has obscured their more ethically benign and medically useful applications . Jeffery housdoff 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 other in the ankle and adds a computer to the ankle to calculate the duration of each stride(step).
Young healthy people can regulate the duration of each step very accurately , but elderly patients prone to frequent falls have extremely variable stride times . by using this information doctors can change their medication and ask them to do exercises . Hausdorff is also is also using the system to determine the success of treatment of congestive heart failure . By monitoring the number of strides that a person takes , he can directly measure the patients activity level , by passing the often flawed estimate made by patient Oxy sensors
The working model of an oxygen 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 sensor will be useful not only to monitor breathing in the intensive care units, but also to check that packages of food or containers of semi conductors stored under nitrogen gas, remain air tight.
Another version of an oxygen sensing chip currently under development sends like pulses out into the body. The light is absorbed to varying extends, depending on how much oxygen is being carried in the blood, and this chip detects the light that is left. The rushes of blood pumped by the heart or also detected, so the same chip is pulse monitor. The number of companies already make large scale versions of such detectors.
This oxygen chip is perhaps about two years away, but the dimensions of another temperature – sensing chip has been reduced to 3mm per side. The transition of certain semi conductors 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 patience who can be plagued by sudden raises in body temperature in response to their anti cancer drugs.
Brain Surgery with an on off switch
Sensing and measuring is one thing, but can we switch the body on and off? Heart pace makers use the crude approach : large jolts of electricity to synchronize the pumping of the heart. The electric pulses of the Activa implant, made by US – based medtronics or directed not at the heart but the brain, they turn off brain signals that cause the uncontrolled movements, or tremors, associated with diseases such as Parkinson’s.
Drug therapy for Parkinson’s disease aims to replace the brain messenger, dopamine, the product of the brain cells that are dying. But eventually that drugs affects wear off, and the erratic movements come charging back.
The activa implant , cleared for use in the US in AUG, 1997 is a new alternative that users high frequency electrical pulses to reversibly shut off the thalamus. The implementation surgery is far less traumatic than thalamotony
And if there are any post operative problems the stimulator can simply be turned off. The implant primarily interferes with aberrant brain functioning.
Adding Sound To Life
The most ambitious bio engineers 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 individuals no amount of amplification is enough.
The cochlear implant delivers electrical pulses directly to the nerve cellsIn the cochlea, the spiral-shaped structure that translates sound into 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 noises ( deep notes) vibrate the base of the cochlea, while low frequency notes vibrate nearer the top of the spiral. The implant mimics the job of the hair cells. It splits the frequencies of incoming noises into a number of channels ( typically eight)
And then stimulates the appropriate part of the cochlea.
‘Clarion ‘ and ‘Nucleus’
the two most successful cochlear implants are the clarion ( developed at the university of California at San Francisco (UCSF) and Advanced Bionics Corporation of Sylmar in California) and the Nucleus ( developed at the University of Melbourne,Australis, and made by cochlear of Sydney, Australia).
Upgrades largely focus on improving the speech processing software, which is operated by a minicomputer worn on the patient’s belt. Theoretically, increasing the number of channels( and electrodes) could improve sound perception.
But speech is perceived in an area of the cochlea only 14mm long, and spacing the electrodes too close to each other causes signals to bleed from one channel to another.
The result is a broad brush version of hearing.while some recipients of the devices report speech like sounds,many characterise their new world as being populated with quacking ducks or banging garbage cans. But the success is undeniable.currently two thirds to three quarters of patients (with more recent models) can understand speech without lip reading says Steve Rebscher,a member of UCSF team.”its pretty amazing , and certainly better than a lot of people anticipated these devices would do”.
EXPERIMENTS WITH LOST SIGHT:-
With the ear atleast partially conquered , the next logical target is the eye. Several groups are working on implantable chips that mimic the action of photo receptors , the light sensing cells at the back of the eye. Photo receptors are lost in retinitis pigmentosa , a genetic disease,and in age related macular degeneration , the most common cause of lost sight in the developed world. Joseph Rizzo of the Massachusetts eye and ear infirmary , and john Wyatt of the Massachusetts institute of technology have made a twenty electrode,1mm square chip,and implanted it at the back of rabbits eyes.
The original chip,the thickness of human hair,put too much stress on the eyes the new version is ten times thinner. The final set up will include a fancy camera mounted on a pair of glasses.The camera will detect and encode the scene,then send it in to the eye as a ;laser pulse,with the laser also providing the energy to drive the chip.
Rizzo has confirmed that his tiny array of light receivers(photo diodes) can generate enough electricity to run the chip.He has also found that the amount of electricity needed to fire a nerve cell into action is about hundred fold lower in the eye 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 into the eye and ,using this device , Rizzo has detected signals reaching the brain. Eugene de Juan of Johns Hopkins Wilmer eye Institute is trying to answer that question by using human subjects.His electrodes , inserted directly in to the eye , are large and some what crude .But his results have been startling . Completely blind patients have seen well defined flashes, which change in position and brightness as De Juan changes the position of the electrode for the amount of current.
In his most recent experiments , patients have identified simple shapes out lined by multiple electrodes . With as little as an 8x8 array , de Juan believes he could approximate character recognition, and a 25x25 array might give a crude image.
The big money in eye implant is in Germany , where the government has pledged millions of US$.One is similar to the US projects in which chips are implanted on the surface of the retina,the structure at the back of the eye.the other project is putting its implants at the back of the retina where the photo receptors are normally found.These “subretinal” chips may block the transport of oxygen and food to the overlying nerve cells, so Everhart Zrenner of the university of Tubinger of Germany is developing ‘chain mail’ electrode arrays, with plenty of holes for the delivery of supplies.
BIOCHIPS
Biochips were invented 9 years ago by gene scientist Stephen Fodor . In a flash of light he saw that photolithography, the process used to etch semi conductor circuits in to silicon could also be used to assemble particular DNA molecules on a chip.
The human body is the next biggest target of chip makers . medical researchers have been working since a long period to integrate humans body and chips . In no time or at maximum within a short period of time Biochips can get implanted into the body of humans . So integration of humans and chips is achieved this way .
Money and research has already gone into this area of technology .Anyway such implants are already being experimented with animals . A
simple chip is being is being implanted into tens of thousands of animals especially pets.
DEFINITION:-
A biochip is a collection of miniaturized test sites (microarrays)
Arranged on a solid substrate that permits many tests to be performed
At the same time inorder to achieve higher throughput and speed .
Typically a biochips surface is no larger than a finger nail . Like
A computer chip that can perform millions of mathematical operations
In one second , a biochip can perform thousands of biological reactions
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 ( deoxyribo nucleic acid ) , the basic chemical instruction that determines the characterstics of an organism . effectively , it is used as a kind of “ test tube “ for real chemical samples. A specially designed microscope can determine where the sample hybridised with DNA strands in the biochip.
IN WHAT WAY THEY WORK:-
The chips are of the 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 a database listing of registered pets .
GETTING UNDER THE SKIN :-
Hausdorffs chips are external , but another chip currently under development will be injected under skin . The chips will allow diabetics to monitor the level of sugar glucose in their blood . Diabetics currently use a skin prick and a handheld blood test and then medicate themselves with insulin , depending on the result . The system is simple and works well , but drawing blood each time is pain full so patients donot test themselves as often as it is needed
THE S4MS CHIP:-
The new s4ms chip will get underneath the skin sense the glucose level and send the result back by radio frequency communication. A light emitting diode starts of the detection process . The light that it produces hits a fluorescent chemical : one that absorbs incoming light and re emits it at a longer wavelength . The longer wavelength of light is then detected , and the result is sent to a control panel outside the body . Glucose is detected, because the sugar reduces the amount of light that the florescent chemical re emits . the more glucose there is 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 the 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 22W LED, almost 40 times less powerful than the tiny power on buttons on a computer keyboard. The low power requirements mean that energy can be supplied from the outside, by the process called induction. The fluorescent detection itself does not consume any chemicals or proteins, so the device is self – sustaining
THE S4MS CHIP:-
The new s4ms chip will get underneath the skin sense the glucose level and send the result back by radio frequency communication. A light emitting diode starts of the detection process . The light that it produces hits a fluorescent chemical : one that absorbs incoming light and re emits it at a longer wavelength . The longer wavelength of light is then detected , and the result is sent to a control panel outside the body . Glucose is detected, because the sugar reduces the amount of light that the florescent chemical re emits . the more glucose there is 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 the 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 22W LED, almost 40 times less powerful than the tiny power on buttons on a computer keyboard. The low power requirements mean that energy can be supplied from the outside, by the process called induction. The fluorescent detection itself does not consume any chemicals or proteins, so the device is self – sustaining
BIOCHIPS USED TO DETECT AND MONITOR DISEASES:-
CHIPS THAT FOLLOW FOOT STEPS : -
The civil debate over biochips has obscured their more ethically benign and medically useful applications . Jeffery housdoff 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 other in the ankle and adds a computer to the ankle to calculate the duration of each stride(step).
Young healthy people can regulate the duration of each step very accurately , but elderly patients prone to frequent falls have extremely variable stride times . by using this information doctors can change their medication and ask them to do exercises . Hausdorff is also is also using the system to determine the success of treatment of congestive heart failure . By monitoring the number of strides that a person takes , he can directly measure the patients activity level , by passing the often flawed estimate made by patient Oxy sensors
The working model of an oxygen 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 sensor will be useful not only to monitor breathing in the intensive care units, but also to check that packages of food or containers of semi conductors stored under nitrogen gas, remain air tight.
Another version of an oxygen sensing chip currently under development sends like pulses out into the body. The light is absorbed to varying extends, depending on how much oxygen is being carried in the blood, and this chip detects the light that is left. The rushes of blood pumped by the heart or also detected, so the same chip is pulse monitor. The number of companies already make large scale versions of such detectors.
This oxygen chip is perhaps about two years away, but the dimensions of another temperature – sensing chip has been reduced to 3mm per side. The transition of certain semi conductors 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 patience who can be plagued by sudden raises in body temperature in response to their anti cancer drugs.
Brain Surgery with an on off switch
Sensing and measuring is one thing, but can we switch the body on and off? Heart pace makers use the crude approach : large jolts of electricity to synchronize the pumping of the heart. The electric pulses of the Activa implant, made by US – based medtronics or directed not at the heart but the brain, they turn off brain signals that cause the uncontrolled movements, or tremors, associated with diseases such as Parkinson’s.
Drug therapy for Parkinson’s disease aims to replace the brain messenger, dopamine, the product of the brain cells that are dying. But eventually that drugs affects wear off, and the erratic movements come charging back.
The activa implant , cleared for use in the US in AUG, 1997 is a new alternative that users high frequency electrical pulses to reversibly shut off the thalamus. The implementation surgery is far less traumatic than thalamotony
And if there are any post operative problems the stimulator can simply be turned off. The implant primarily interferes with aberrant brain functioning.
Adding Sound To Life
The most ambitious bio engineers 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 individuals no amount of amplification is enough.
The cochlear implant delivers electrical pulses directly to the nerve cellsIn the cochlea, the spiral-shaped structure that translates sound into 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 noises ( deep notes) vibrate the base of the cochlea, while low frequency notes vibrate nearer the top of the spiral. The implant mimics the job of the hair cells. It splits the frequencies of incoming noises into a number of channels ( typically eight)
And then stimulates the appropriate part of the cochlea.
‘Clarion ‘ and ‘Nucleus’
the two most successful cochlear implants are the clarion ( developed at the university of California at San Francisco (UCSF) and Advanced Bionics Corporation of Sylmar in California) and the Nucleus ( developed at the University of Melbourne,Australis, and made by cochlear of Sydney, Australia).
Upgrades largely focus on improving the speech processing software, which is operated by a minicomputer worn on the patient’s belt. Theoretically, increasing the number of channels( and electrodes) could improve sound perception.
But speech is perceived in an area of the cochlea only 14mm long, and spacing the electrodes too close to each other causes signals to bleed from one channel to another.
The result is a broad brush version of hearing.while some recipients of the devices report speech like sounds,many characterise their new world as being populated with quacking ducks or banging garbage cans. But the success is undeniable.currently two thirds to three quarters of patients (with more recent models) can understand speech without lip reading says Steve Rebscher,a member of UCSF team.”its pretty amazing , and certainly better than a lot of people anticipated these devices would do”.
EXPERIMENTS WITH LOST SIGHT:-
With the ear atleast partially conquered , the next logical target is the eye. Several groups are working on implantable chips that mimic the action of photo receptors , the light sensing cells at the back of the eye. Photo receptors are lost in retinitis pigmentosa , a genetic disease,and in age related macular degeneration , the most common cause of lost sight in the developed world. Joseph Rizzo of the Massachusetts eye and ear infirmary , and john Wyatt of the Massachusetts institute of technology have made a twenty electrode,1mm square chip,and implanted it at the back of rabbits eyes.
The original chip,the thickness of human hair,put too much stress on the eyes the new version is ten times thinner. The final set up will include a fancy camera mounted on a pair of glasses.The camera will detect and encode the scene,then send it in to the eye as a ;laser pulse,with the laser also providing the energy to drive the chip.
Rizzo has confirmed that his tiny array of light receivers(photo diodes) can generate enough electricity to run the chip.He has also found that the amount of electricity needed to fire a nerve cell into action is about hundred fold lower in the eye 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 into the eye and ,using this device , Rizzo has detected signals reaching the brain. Eugene de Juan of Johns Hopkins Wilmer eye Institute is trying to answer that question by using human subjects.His electrodes , inserted directly in to the eye , are large and some what crude .But his results have been startling . Completely blind patients have seen well defined flashes, which change in position and brightness as De Juan changes the position of the electrode for the amount of current.
In his most recent experiments , patients have identified simple shapes out lined by multiple electrodes . With as little as an 8x8 array , de Juan believes he could approximate character recognition, and a 25x25 array might give a crude image.
The big money in eye implant is in Germany , where the government has pledged millions of US$.One is similar to the US projects in which chips are implanted on the surface of the retina,the structure at the back of the eye.the other project is putting its implants at the back of the retina where the photo receptors are normally found.These “subretinal” chips may block the transport of oxygen and food to the overlying nerve cells, so Everhart Zrenner of the university of Tubinger of Germany is developing ‘chain mail’ electrode arrays, with plenty of holes for the delivery of supplies.