Nano Radio - Seminar Report

Abstract

The nano radio is a remarkable break through development that will that have wide ranging repercussions in multi various fields from the detailed study of body living cells sensor applications, drug delivery to cancer affected cells ,control device small enough to exist in a human’s blood stream, and of course playing music and favorite songs and many more applications. 

                  Nano radio is a fully functional, fully integrated radio receiver from a single walled nano tube. The nano tube serves simultaneously as all essential components of a radio: antenna, tunable band pass filter, amplifier and demodulator. A direct current voltage source as applied by a battery powers the radio. Using the carrier waves in the commercially 40-400 MHz range and both frequency and modulated techniques it demonstrated successfully.

                     The white paper reveals about the working of a nano radio with carbon nano tube and electrodes. The carbon nano tube plays a very crucial role in the operation of a nano radio. The multi usage of the single walled carbon nano tube as an antenna , tuner, amplifier and demodulator. The differences between the working of a normal radio and a nano radio can be explained.

                    Any wireless device from cell phone to environmental sensors could benefit from nano radios .Smaller electronic components such as tuners ,would reduce power consumption and extends battery life. Nano radios could also steer wire less communications into entirely new realms  , including tiny devices that navigate the blood stream to release drugs on command.   

                       Nano radios has exciting application areas and opens many possibilities of applications from treating malignant cancer cells  to studying the body cell functions ,home pregnancy resting kits, hearing aids ,cell phones ,I phone and many more are yet to come in the future. Continuous research and developement are carried out by many firms and universities through –out the world.

INTRODUCTION:

                At the core of the nano radio is a single molecule that can receive radio signals. It was developed by Alex Zettl at the university of California, Barkeley .

Introduction:

                Radio has had a profound applications on civilization from its early use in critical communications such as with ships at sea , to its later use during the “golden age “ of radio in the 1930’s as a mass medium for news and entertainment, and finally to it’s more recent use in cellular phones and wireless computer networks and the global positioning system. Historically applications of radio have been tightly linked to available technology. Early spark gap receivers were only capable of receiving on – off signals such as morse -code. Vacume tube technology enabled cheap and reliable audio communication .Perhaps more strikingly the solid state transistor transformed the radio from a bulky, power hungry and stationary unit to a device that could be carried in a shirt pocket. To day the same silicon based technology that gave us the transistor is fast approaching hard physical limits , and it is expected that future progress will require new nano scale materials such as carbon nano tubes.Combining the many of the unique electrical and mechanical properties of the carbon nano tubes a fully functions radio receiver have fabricated ,orders of magnitude smaller than previous radios from a single carbon nano tube. The carbon nao tube radio may lead to radical new applications such as radio controlled devices small enough to exist ina human’s bloodstream or simply smaller cheaper and more efficient wireless devices.

  

Working:

              To understand how the nano tube radio receiver operates, it is instructive to examin how radio receivers works in general, specifically envelope detector radio receivers. 

Envelope detector radios:

These radios consists of four essential components: antenna, tuner, amplifier and de modulator  as shown in the figure 1. The antenna receives the incoming radio transmission. The tuner then filters this received signal, selecting a frequency range of channel of interest. The amplifier increases the generally weak radio signal power to a more robust level. Finally the demodulator typically a non linear device like a diode ,extracts from incoming modulated high frequency radio signal the lower frequency informational signal that depending on application can either be directly amplified and sent to an audio loud speaker or further processed by a computer or other instrument.   

Nano radio:

              A nano radio is a carbon nano tube anchored to an electrode, with a second electrode just beyond its free end. A direct current voltage source such as from a battery is connected to the electrodes and powers the radio. When a voltage is applied between the Electrodes , electrons flow from a battery through the nano tube jumping off its tip to the positive electrode . A radio wave alternately attracts and repells the nano tube tip, causing it to vibrate it in sync. When the tip is farther from the electrode, fewer electrons bridge the gap: the varying electrical signal recovers the audio signal encoded by the radio wave.

 Amazingly all four critical radio receiver components can be simultaneously implemented with a single carbon nano tube. A model of simplicity the entire radio consists of an individual carbon nano tube mounted to mounted to an electrode in close proximity to a counter electrode .A direct current voltage source such as from a battery , is connected to the electrodes and powers the radio. Important for the radios operation , the applied dc bias negatively charges the tip of the nano tube , sensitizing it to oscillating electric fields. Also both the electrodes and nano tubes arecontained in vaccum below 10^(-7)  torr. Interestingly the geometrical configuration is reminiscent of a convensional vaccum tube and indeed there are some key functiona similarities between the two.

Nano tube radios Vs traditional radios 

             The nano tube radio operates in a radically different manner than traditional radios . Whereas traditional radios are entairely electrical in nature , the nano  tube radio functions at least in part mechanically. Briefely electro magnetic waves from an incoming radio transmission impinge upon the nano tube forcing it to physically vibrate through their action on the charged tip. The vibrations are only significant when the vibrations of the incoming wave coincides with the nano ubes flexural resonance frequency . The nano tube’s  resonance frequency can be tuned during the operation and hence the nano tube radio ,like any good radio can be tuned to receive only a preselected band of the electromagnetic spectrum.

Operation:

               The amplification and demodulation stages rely on the remarkable field emission properties of carbon nano tubes which are due in large part to their needle –point geometry that concentrates the electric field . The dc bias voltage applied across the electrodes produces a nominally constant field emission current . Mechanical vibrations of the nano tube modulate the field emission current which then serves as the easily detected electrical signal.Because the battery voltage source rather than the incoming electro magnetic wave powers the field emission current amplification of the radio signal is possible. Also due to nonlinearities inherent in field emission, demodulation of the radio signal occurs as well. Thus all four essential components of a radio receiver are compactly and efficiently

implemented by  the vibrating and field emitting nano tube.

Because of the critical role played by  mechanical motion of the nano tube during radio   operation , visual observation of the nano tube radio is invaluable.The rasearchers accomplished this by mounting the nano tube radio inside a high resolution transmission electron microscope. A sine wave carrier radio signal was launched from a near by transmitting antenna.Figure shows the TEM micrograph of the nano tube attatched to the cathode. In the upper image the nano tube resonance frequency does not match the transmitted carrier wave frequency; the nano tube is relatively motionless and no radio reception can occur. Apparent in this image is the negative charging of the tip of the nano tube which manifests itself as a significant brightening towards the nano tube’s tip.In the lower image the nano tubes resonance frequency has brought into tune wth the transmission carrier wave frequency .Here the oscillating electric field of the radio signal resonately drives the charged nano tube  causing it to vibrate vigorously there by blurring its image. During this resonance condition radio reception is possible. 

Turn now to details of a nano tube radio operation and ultimate sensitivity limits.The resonance frequency of the nano tube radio Is tuned using a two step process. An initial coarse tuning adjusts the operational frequency band by trimming or shortening , the length of the nano tube . To accomplish this a high field emission current , which is much higher than used for radio operation , is run through the nano tub and as a result carbon atoms are ejected from end of the  nanotube permanently alternating its length. The trimming process is terminated once the nanotube ‘s resonance frequency reaches the target frequenc band. Fine tuning of the radio within the desired band is accomplished by tensioning the nano tube with an electro static field. Thus much as a guitar is tuned by tensioning it’s strings , the nano tubesreonance frequency is tuned through small adjustments to the already established dc bias voltage.

             The antenna is implemented by the charged tip of the nano tube .this is substancially differ than the other proposals that use nano tubes as scaled down version of macroscopic antenna. The quantity of the charge at the tip critically affects the performance the antenna.

Nano tube radio simulation

This simulation shows the electric field surrounding the nano tube radio during radio operation .  Notice how the field is strongest at the tip of the nano tube and how the field varies as the nano tube vibrates. This effect allows the nano tube radio todemodulate electric signals.

Revolutionary applications:

The nano tube radio could be the basis for a range of rivolutionar applications :heating aids , cell phone and ipods small enough to fit completey with in the ear canal.The nano radio would easily fit inside a living cell One ca envision interfaces to brain or muscle functions or radio controlled devices moving through the blood stream.The nano tube radio may lead to radical new applications such as radio controlled devices small enough toexist in a human’s blood stream.

 The nano tube radio is potentially a transformative technology and killer applications from a whole new generation of communications devices, brain and muscle implants are possible. Where as some of these more futuristic applications will require a non trivial amount of additional insight ad engineering to make them into operational realities , others are more real term in the form of radio – controlled drug delivery systems.

Radio based drug delivery vehicles

                    Nano radio attatched to tiny chemical sensors could be implemented in the blood vessels of patients with diabetis or other deseases.If the sensor detect an abnormal level of insulin or some other target compound ,the transmitter could then relay the information to a detector , or perhaps even to an implanted drug reservoir that could release insulin or another therapeutic on cue. 

              Drug containing capsules equipped with nano radios home to cancer cells and relese their payloads on receipt of a signal from outside the patient’s body. 

                The nano radio which is currently configured as a receiver but also could work as a transmitter, is 100 billion times smaller than the first commercial radios , and could be used in any number of applications – from cell phone to micro scopic devices that sense the environment and relay information via radio signals . Because it is extremely energy efficient , it would integrate well with micro electronic circuts.

One of the downtrends of chemotherapy for shrinking invisible cancers that have spread or for treating in operale ones is that the chemical agents used to kill cancer cells travel through the blood streams to all parts of the body . A solution advanced by some physicians would be to first inject packages that are molecularlu targeted to cancer cells and that contain a chemo agent as well as a nano radio ; after allowing the packages time to find the tumors, radio control signals would trigger release of the drug into the tumor cells for their destruction. 

                A second use would be to repair individual cells by injecting drugs into them . The group has moved in this direction by working on a fine scale approach to nano injection in which the researchers punctured cell walls and memberances and put nano tube structures inside, where they released specific chemicals.

               The cells withstand that very nicely . This nano injaction technique works much better than the old technique where people used to try to use micropipettes that puncture cells and inject flud.Those are way too crude and disruptive for most living cells . researchers also foresee an application of original nano tube mass sensor. Some types of explosives contain signature molecules of a known mass, and so a miniscule instrument that detects those molecules rapidly and reliably could replace the refrigerator size explosives sensing mass spectrometers now in use at some airport security check points.     

 Interesting features:

• The high speed carbon transistors only on thousandth the power of today’s transistors.
• The battery life extends to several to weeks.
• The device is less than 10 microns long and only 10 nano meters wide or one thousand of times smaller than the diameter of a human hair.
• Any wireless device from cell phone to environmental sensors could benefit from nano radios.
• Smaller electronic components such as tuners would reduce the powerconsumption and extend the battery life.
• These could also steer wireless communications into entirely new realms, including tiny devices that can navigate the blood stream to release the drug on command.

Conclusion:

Nano radio has exciting application areasand opens many possibilities of applications from treating malignant cancer cells, to studying the body cell functions home pregnancy resting kits, hearing aids ,cell phones , I phones and many moreyet to come in  future . Continuous research and development are carried out by many firms and universities through out the world.