University of Dayton (Dayton, OH) and Honda Motor Co., Ltd. (Tokyo, JP) received U.S. Patent 7,777,478 for improved touch and auditory sensors based on carbon nanotube arrays. The sensor includes at least one sensor probe comprising: a pair of electrodes; a vertically aligned nanotube disposed between the pair of electrodes; optionally a piezoelectric polymer on the nanotube; and optionally, a field source for generating a field, the field source operatively connected to the pair of electrodes; whereby when the sensor probe is contacted, a change in the field occurs or electricity is generated.
Another aspect of the shared invention is a method of detecting touch or sound. The method includes providing a sensor comprising: at least one sensor probe comprising: a pair of electrodes; a vertically aligned nanotube disposed between the pair of electrodes; optionally a piezoelectric polymer on the nanotube; and optionally, a field source for generating a field, the field source operatively connected to the pair of electrodes; whereby when the sensor probe is contacted, a change in the field occurs or electricity is generated; contacting the sensor probe causing a change in the field or generating electricity; and detecting the change in the field or the electricity generation.
Another aspect of the shared invention is a method of detecting touch or sound. The method includes providing a sensor comprising: at least one sensor probe comprising: a pair of electrodes; a vertically aligned nanotube disposed between the pair of electrodes; optionally a piezoelectric polymer on the nanotube; and optionally, a field source for generating a field, the field source operatively connected to the pair of electrodes; whereby when the sensor probe is contacted, a change in the field occurs or electricity is generated; contacting the sensor probe causing a change in the field or generating electricity; and detecting the change in the field or the electricity generation.
Nanostructured materials have opened the door to realizing devices with ultra-miniature sizes and ultra low electric consumptions, which conventional materials could not have achieved. Nanostructured materials, which can be defined as materials with crystallite sizes less than 100 nm in dimension, are typically synthesized by either "bottom-up" or "top-down" processes. The bottom-up process starts with atoms, ions or molecules as "building blocks" and assembles nanoscale clusters or bulk material from them.
The "top-down" methods for processing of nanostructured materials involve starting with a bulk solid and obtaining a nanostructure by structural decomposition. One such approach involves the lithography/etching of bulk material analogous to the processes used in the semiconductor industry wherein devices are formed out of an electronic substrate by pattern formation (such as electron beam lithography) and pattern transfer processes (such as reactive ion etching) to make structures at the nanoscale.
Carbon nanotubes (CNTs) are expected to be adopted for many applications because of their superior electrical and mechanical characteristics. Moreover, their unique structures are also attractive for sensor applications. For example, in the case of using semi conducting CNTs as a sensor, it is possible to identify gases based on the selection of a donor or an acceptor by control of electron charity. In contrast, conventional gas sensors only detect the change of the electric resistance by gas absorption. However, as this new type of sensor uses only one CNT as a sensor probe for detection of gases, many difficulties remain in producing such a device.
For example, in order to produce the gas sensor described above, the CNT must be isolated from the carbon soot that was prepared, and it must be moved and set on a desirable point via a "manipulation" process. Today, the manipulations of CNTs are performed using hand-made nano-tweezers used in a transmitting electron microscope (TEM), and carried out using the "top-down" method in this special and limited environment. However, these operations are not adaptable to make uniform devices or to set a plurality of sensors on one chip.
On the other hand, a gas sensor containing an anode with a vertically aligned CNT array and a cathode has been reported in the prior art. The sensor works by applying a DC voltage to two electrodes, and flowing gas between those electrodes. Ionized gas produced by the voltage affects a breakdown voltage of the CNT array. By observing the differences in the breakdown voltage, the type of gas can be identified.
Vertically aligned CNT arrays are currently produced using the "bottom-up" method. In particular, the CNT arrays are generally made using a chemical vapor deposition (CVD) process with catalysts, namely the pyrolysis of compounds containing a carbon source and catalyst elements. Based on these CNT arrays, CNTs with proper alignment are produced easily, such that a plurality of sensors can be set on single chip.
Carbon nanotubes (CNTs) are expected to be adopted for many applications because of their superior electrical and mechanical characteristics. Moreover, their unique structures are also attractive for sensor applications. For example, in the case of using semi conducting CNTs as a sensor, it is possible to identify gases based on the selection of a donor or an acceptor by control of electron charity. In contrast, conventional gas sensors only detect the change of the electric resistance by gas absorption. However, as this new type of sensor uses only one CNT as a sensor probe for detection of gases, many difficulties remain in producing such a device.
For example, in order to produce the gas sensor described above, the CNT must be isolated from the carbon soot that was prepared, and it must be moved and set on a desirable point via a "manipulation" process. Today, the manipulations of CNTs are performed using hand-made nano-tweezers used in a transmitting electron microscope (TEM), and carried out using the "top-down" method in this special and limited environment. However, these operations are not adaptable to make uniform devices or to set a plurality of sensors on one chip.
On the other hand, a gas sensor containing an anode with a vertically aligned CNT array and a cathode has been reported in the prior art. The sensor works by applying a DC voltage to two electrodes, and flowing gas between those electrodes. Ionized gas produced by the voltage affects a breakdown voltage of the CNT array. By observing the differences in the breakdown voltage, the type of gas can be identified.
Vertically aligned CNT arrays are currently produced using the "bottom-up" method. In particular, the CNT arrays are generally made using a chemical vapor deposition (CVD) process with catalysts, namely the pyrolysis of compounds containing a carbon source and catalyst elements. Based on these CNT arrays, CNTs with proper alignment are produced easily, such that a plurality of sensors can be set on single chip.
No comments:
Post a Comment