NZ617143B2 - Apparatus and method to generate x-rays by contact electrification - Google Patents
Apparatus and method to generate x-rays by contact electrification Download PDFInfo
- Publication number
- NZ617143B2 NZ617143B2 NZ617143A NZ61714312A NZ617143B2 NZ 617143 B2 NZ617143 B2 NZ 617143B2 NZ 617143 A NZ617143 A NZ 617143A NZ 61714312 A NZ61714312 A NZ 61714312A NZ 617143 B2 NZ617143 B2 NZ 617143B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- rollers
- roller
- triboelectric
- enclosing vessel
- triboelectric material
- Prior art date
Links
- 239000000463 material Substances 0.000 claims abstract description 92
- 238000005096 rolling process Methods 0.000 claims abstract description 27
- 238000003384 imaging method Methods 0.000 claims description 22
- 238000002083 X-ray spectrum Methods 0.000 claims description 8
- 239000003990 capacitor Substances 0.000 claims description 6
- 230000005281 excited state Effects 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 230000000875 corresponding Effects 0.000 claims 2
- 230000004907 flux Effects 0.000 description 13
- 238000004846 x-ray emission Methods 0.000 description 11
- 239000004698 Polyethylene (PE) Substances 0.000 description 8
- -1 polyethylene Polymers 0.000 description 8
- 229920000573 polyethylene Polymers 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 7
- 229920000642 polymer Polymers 0.000 description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 239000011733 molybdenum Substances 0.000 description 4
- 239000004820 Pressure-sensitive adhesive Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000005390 triboluminescence Methods 0.000 description 3
- 206010036618 Premenstrual syndrome Diseases 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000000576 supplementary Effects 0.000 description 2
- 210000000481 Breast Anatomy 0.000 description 1
- RPPBZEBXAAZZJH-UHFFFAOYSA-N Cadmium telluride Chemical compound [Te]=[Cd] RPPBZEBXAAZZJH-UHFFFAOYSA-N 0.000 description 1
- 229910004613 CdTe Inorganic materials 0.000 description 1
- 241000287828 Gallus gallus Species 0.000 description 1
- 239000002800 charge carrier Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005421 electrostatic potential Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000009607 mammography Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000010943 off-gassing Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000003595 spectral Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000003325 tomography Methods 0.000 description 1
- 210000000689 upper leg Anatomy 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G2/00—Apparatus or processes specially adapted for producing X-rays, not involving X-ray tubes, e.g. involving generation of a plasma
Abstract
x-ray source includes an enclosing vessel, a first roller arranged at least partially within the enclosing vessel, a second roller arranged at least partially within the enclosing vessel and to be in rolling contact with the first roller, and a drive assembly operatively connected to at least one of the first and second rollers. The drive assembly causes the first and second rollers to rotate while in contact to bring portions of the first and second rollers into and out of contact within the enclosing vessel as the first and second rollers rotate. The first roller has a surface at least partially of a first triboelectric material and the second roller has a surface at least partially of a second triboelectric material, the first triboelectric material having a negative triboelectric potential relative to the second triboelectric material. The enclosing vessel is structured to provide a controlled atmospheric environment, and the first triboelectric material, the second triboelectric material and the controlled atmospheric environment are selected such that rolling contact between the first and second rollers produces x-rays. The x-ray source may form part of a system that also includes an x-ray detector. of the first and second rollers. The drive assembly causes the first and second rollers to rotate while in contact to bring portions of the first and second rollers into and out of contact within the enclosing vessel as the first and second rollers rotate. The first roller has a surface at least partially of a first triboelectric material and the second roller has a surface at least partially of a second triboelectric material, the first triboelectric material having a negative triboelectric potential relative to the second triboelectric material. The enclosing vessel is structured to provide a controlled atmospheric environment, and the first triboelectric material, the second triboelectric material and the controlled atmospheric environment are selected such that rolling contact between the first and second rollers produces x-rays. The x-ray source may form part of a system that also includes an x-ray detector.
Description
APPARATUS AND METHOD TO GENERATE X-RAYS BY CONTACT
ELECTRIFICATION
CROSS-REFERENCE OF RELATED APPLICATION
This application claims priority to U.S. Provisional Application No.
61/482,031 filed May 3, 201 1, the entire contents of which are hereby incorporated by
reference.
This invention was made with U.S. Government support of Grant No.
W81XWH1-1049, awarded by the ARMY/Medical Research and Materiel
Command. The U.S. Government has certain rights in this invention.
BACKGROUND
1. Field of Invention
The field of the currently claimed embodiments of this invention relates to
triboelectric x-ray sources and systems.
2. Discussion of Related Art
Triboelectricity has been utilized in fundamental scientific research as a
source of high electrostatic potential for over three centuries from the early electrostatic
apparatus of Haukesbee (F. Haukesbee, Physico-Mechanical experiments on various
subjects (London: 1709)) through to the eponymous generators of van der Graaf, yet there
remains a notable absence of a first principles approach to the subject (M. Stoneham,
Modelling Simul. Mater. Sci. Eng. 17, 084009 (2009)). Electrostatic generators store the
integrated charge that is developed when two materials are rubbed together in frictional
contact. The materials are selected to be furthest apart in the triboelectric series-an
empirically derived list showing both the propensity of the materials to charge and the
polarity of charge (P. E. Shaw, Proc. R. Soc. Lond. A 94, 16 (1917)). At the point of
contact between the two materials, the frictional electrification may be of such magnitude
that it may ionize the gas surrounding it, creating triboluminescence. The
triboluminescence observed during peeling pressure sensitive adhesive (PSA) tape has
long attracted scientific attention (E. N . Harvey, Science 89, 460 (1939)) and has an
12 -2
electrostatic origin. When the tape is peeled, charge densities 10 e cm (where is e is
the fundamental charge on the electron) are exposed on the surfaces of the freshly peeled
region and subsequently discharge (C. G. Camara, J. V. Escobar, J. R. Hird and S. P.
Putterman, Nature 455, 1089 (2008)). If the tape is peeled in vacuum -10 mTorr, it has
been found that the triboluminescence produced extends to X-ray energies (V. V.
Karasev, N . A. Krotova and B. W. Deryagin, Dokl. Akad. Nauk. SSR 88 777 (1953)).
More recently (Camara, et al., id.), it was found that there are two timescales for
tribocharging during the peeling of tape in vacuo: the first, common to electrostatic
generators and classic electrostatic experiments (W. R. Harper, Contact andfrictional
electrification, (Oxford University Press, London, 1967)), is the long timescale process
-2
which results in an average charge density of 10 e cm being maintained on the surface
12 -2
of the tape and second, a nanosecond process with charge densities of 10 e cm . In
addition, it was found that the X-ray discharge from peeling tape was sufficiently self-
collimated at the peel line to resolve the inter-phlangeal spacing of a human digit. The
emission of nanosecond X-ray pulses allowed an estimate of the emission region to be
calculated. Subsequent research on peeling PSA tape with a width of 1.5 mm has
confirmed that the process takes place at dimensions less than 300 mih (C. G. Camara, J.
V. Escobar, J. R. Hird and S. P. Putterman, Appl. Phys. B 99, 613 (2010)).
Underpinning this recent work on triboelectricity is a resurgence of interest
in how charge transfer occurs between different materials and particularly between
polymers. Particularly intriguing is the report of like-polymers charging each other (M.
M. Apodaca, P. J. Wesson, K. J. M. Bishop, M. A. Ratner and B. A. Grzybowski, Angew.
Chem. Int. Ed. 49, 946 (2010)). More fundamentally, an open question is whether the
transfer particle is an ion (L. McCathy and G. M. Whitesides, Angew. Chem. Int. Ed. 47,
2188 (2008)) or an electron (Harper, id.) - a matter that is still debated despite centuries
of experimental research. Whether the charge carriers responsible for tribocharging are
electrons or ions, what is clear is that very large charge densities are readily generated.
For the most effective charging to occur, intimate contact between the
materials and cleanliness of the contacting surfaces is important (R. Budakian, K.
Weninger, R. A. HiUer and S. P. Putterman, Nature 391, 266 (1998)). While the peeling
geometry of PSA tapes is mathematically elegant (A. D. McEwan and G. I. Taylor, J.
Fluid Mech. 26, 1 (1966)) and meets both criteria, a disadvantage of using these for a
portable X-ray device not requiring a high voltage supply is, however, the significant out-
gassing that occurs during peeling off-the-shelf tape in vacuo (E. Constable, J. Horvat and
R. A . Lewis, Appl. Phys. Lett. 97, 131502 (2010)) as well as practical issues such as
reliability, wear, etc. There thus remains a need for improved triboelectric x-ray sources
and systems.
SUMMARY
An x-ray source according to an embodiment of the current invention
includes an enclosing vessel, a first roller arranged at least partially within the enclosing
vessel, a second roller arranged at least partially within the enclosing vessel and to be in
rolling contact with the first roller, and a drive assembly operatively connected to at least
one of the first and second rollers. The drive assembly causes the first and second rollers
to rotate while in contact to bring portions of the first and second rollers into and out of
contact within the enclosing vessel as the first and second rollers rotate. The first roller
has a surface at least partially of a first triboelectric material and the second roller has a
surface at least partially of a second triboelectric material, the first triboelectric material
having a negative triboelectric potential relative to the second triboelectric material. The
enclosing vessel is structured to provide a controlled atmospheric environment, and
the first triboelectric material, the second triboelectric material and the controlled
atmospheric environment are selected such that rolling contact between the first and
second rollers produces x-rays.
An x-ray imaging system according to an embodiment of the current
invention includes an x-ray source, and an x-ray detector. The x-ray source includes
an enclosing vessel, a first roller arranged at least partially within the enclosing vessel, a
second roller arranged at least partially within the enclosing vessel and to be in rolling
contact with the first roller, and a drive assembly operatively connected to at least one of
the first and second rollers. The drive assembly causes the first and second rollers to
rotate while in contact to bring portions of the first and second rollers into and out of
contact within the enclosing vessel as the first and second rollers rotate. The first roller
has a surface at least partially of a first triboelectric material and the second roller has a
surface at least partially of a second triboelectric material, the first triboelectric material
having a negative triboelectric potential relative to the second triboelectric material. The
enclosing vessel is structured to provide a controlled atmospheric environment, and
the first triboelectric material, the second triboelectric material and the controlled
atmospheric environment are selected such that rolling contact between the first and
second rollers produces x-rays.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objectives and advantages will become apparent from a
consideration of the description, drawings, and examples.
is a schematic illustration of an X-ray source, with a portion of the
enclosing vessel removed, according to an embodiment of the current invention.
is a schematic illustration of side view of an X-ray source, with
the enclosing vessel removed, according to an embodiment of the current invention.
is a schematic illustration of top view of an X-ray source, with a
portion of the enclosing vessel removed, according to an embodiment of the current
invention.
is a schematic illustration of a close-up view of a contact region
between two rollers to help explain some concepts of the current invention.
is a schematic illustration of an X-ray source according to an
embodiment of the current invention.
is a schematic illustration of an X-ray source according to an
embodiment of the current invention.
is a schematic illustration of an X-ray source according to an
embodiment of the current invention.
is a schematic illustration of an X-ray system according to an
embodiment of the current invention.
shows an example of X-ray emission from 2cm wide rollers
brought into contact by tension springs and made to rotate at 300 rpm at an ambient
pressure of 1 x 10 Torr. One roller was covered with lead tape and the other with a layer
of tape (treated polyethylene).
shows an example of X-ray flux as a function of rotation speed for
different systems. Black squares represent the summary of our previous published results
for peeling scotch tape. Figure 2 Nature Supplementary is the integrated flux used to
obtain previously published x-ray images by peeling 2cm wide tape at 20cm/s. Figure 2
Nature is the integrated flux from peeling 2cm tape at 3.6cm/s. Figure 3 APB is the flux
obtained from peeling a 1.5mm strip of tape at 3.6cm/s. The diamonds represent data
from peeling 2cm wide scotch tape, showing that this system also scales linearly with
rotation speed. The dots represent data from a lead roller in contact with tape backing
(treated polyethylene). The inset shows averaged values for representative velocities.
shows an example of an X-ray spectrum for 2cm wide rollers in
contact at an ambient pressure of 5xl0 Torr and a tangential velocity of 3cm/s. The top
trace is the spectrum from a lead roller in contact with tape backing (treated
polyethylene). The lower trace is from a roller of sticky-side-out scotch tape against tape
backing.
shows an example of width of x-ray bursts from a 3mm wide roll
of lead rotating against a polyethylene roller at 3cm/s. Two liquid scintillators coupled to
' PMTs were used to detect x-ray pulses with energy above 50keV, shown in histograms.
The PMT signals were recorded and then fit to a Gaussian to obtain their width. The inset
shows the correlation between the two detectors, indicating that x-ray pulses were indeed
measured. The narrow trace to the right is a histogram of the widths from cosmic rays,
showing that the characteristic signals have a width of 5ns.
shows an X-ray spectrum for 2cm wide rollers in contact at an
ambient pressure of lxlO Torr and a tangential velocity of 3cm/s. The upper trace is the
spectrum from a lead roller in contact with tape backing (treated polyethylene). The
lower trace is from a roller of Molybdenum against tape backing. The characteristic L
lines from Lead and the K lines from Molybdenum can be clearly identified.
FIGS. 12A and 12B provide an example of an X-ray image taken with
contacting rotating rollers, 1cm wide, Pb vs polymer. A shows the object placed
on the window over the source. B shows an x-ray image taken at 200rpm and
30sec exposure.
shows examples of X-ray images of a stainless steel razor 250
micron thick at 0, 45 and 90 degrees according to an embodiment of the current
invention, 2cm from detector and 8cm from vertex. At 0 degrees the razor is pointing
directly into the vertex and perpendicular to the detector. Rollers are 1cm wide rotating at
30rpm and exposure is 30s. Such images can be used for topographic reconstruction.
shows an example of an X-ray image of a padlock and a picture of
the object over a digital x-ray detector, Rad-Icon RadEye200. The detector has an active
area of lOxlOcm and a pixel resolution of IOOmih . The image resolution is about l/4mm.
shows examples of X-ray images of a hand and a broken chicken
thigh according to an embodiment of the current invention.
DETAILED DESCRIPTION
Some embodiments of the current invention are discussed in detail below.
In describing embodiments, specific terminology is employed for the sake of clarity.
However, the invention is not intended to be limited to the specific terminology so
selected. A person skilled in the relevant art will recognize that other equivalent
components can be employed and other methods developed without departing from the
broad concepts of the current invention. All references cited anywhere in this
specification, including the Background and Detailed Description sections, are
incorporated by reference as if each had been individually incorporated.
Some embodiments of the current invention are directed to an apparatus
and a method to generate collimated x-rays without the use of a high voltage power
supply. An x-ray source according to an embodiment of the current invention does not
require high voltage electronics and can be powered by any source of mechanical motion.
We have demonstrated that simply bringing two materials into contacting motion can
generate a flux of x-rays useful for x-ray imaging. The contact geometry can be used to
provide collimation. We have demonstrated a line of x-ray emission which coupled to a
line x-ray detector can provide a simple method to obtain x-ray images. Some
embodiments of the current invention can provide ultra-portable x-ray sources that
require no electricity grid. Previous work by the current inventors can be found in
WO/2009/102784 MECHANOLUMINE SCENT X-RAY GENERATOR, the entire
content of which is incorporated herein by reference. (See, also, Nature v455 1089-1092
(2008) and Appl. Phys. v99 613-617 (2010), the entire contents of which are incorporated
herein by reference.)
This x-ray source requires no high voltage power supply and can be driven
by simple direct mechanical motion. The x-ray emission from contacting rotating rollers
originates from a small region close to the vertex which spans the length of the contact.
The result is a line of x-ray emission. This is a unique capability which distinguishes this
source from all current technology.
Some embodiments of the current invention relate to systems and methods
that provide contacting motion of different materials in a controlled environment as a
source of x-rays which can be collimated and which can be narrow in time and energy. A
simple embodiment of this invention is two rollers of different materials made to rotate by
their contact friction under a partial vacuum as illustrated in Figure 1. This arrangement
can be used to generate a flux of x-rays useful for x-ray imaging. The x-ray emission can
take place both continuously and in nanosecond bursts from a region close to the vertex
which extends the length of the contact.
In addition, the effect of changing the force with which two or more
rolling surfaces are brought into contact can have a large effect on x-ray production
because the force of compression of the surfaces will change the charge transfer. Also
partial rotation and changing rotations can be useful according to some aspects of the
current invention. For example, two surfaces which roll a few degrees in the clockwise
direction can then reverse so that they roll in the counterclockwise direction and then
oscillate in this manner according to an embodiment of the current invention. The
general concepts of this invention are not limited to only cylindrical rollers in contact
with other cylindrical rollers. Surfaces with shapes other than cylindrical can be used
according to some embodiments of the current invention. In some embodiments, one of
the surfaces can be planar, for example, and the other surface can be a roller going back
and forth on the planar surface. The broad concepts of the current invention are not
limited to these particular examples.
Figure 1 is a schematic illustration of an x-ray source 100 according to an
embodiment of the current invention. The x-ray source 100 in Figure 1 is shown in a
partially assembled view to allow internal structure to be viewed. The x-ray source 100
includes an enclosing vessel 102, the lower half of which is shown in Figure 1; a first
roller 104 arranged at least partially within the enclosing vessel 102; a second roller 106
arranged at least partially within the enclosing vessel 102 and to be in rolling contact with
the first roller 104; and a drive assembly 108 (Figure 2A) operatively connected to at least
one of the first roller 104 and second roller 106. The drive assembly 108 causes the first
and second rollers 104, 106 to rotate while in contact to bring portions of the first and
second rollers 104, 106 into and out of contact within the enclosing vessel 102 as the first
and second rollers 104, 106 rotate. The first roller 104 has a surface at least partially of a
first triboelectric material and the second roller 106 has a surface at least partially of a
second triboelectric material. As is shown schematically in Figure 3, the first triboelectric
material has a negative triboelectric potential relative to the second triboelectric material.
However, the general concepts of the current invention are not limited to the
embodiments shown in Figures 1-3. The order of the materials can be reversed in other
embodiments. The enclosing vessel 102 is structured to provide a controlled atmospheric
environment (see, also, Figures 4-6). The first triboelectric material, the second
triboelectric material and the controlled atmospheric environment are selected such that
rolling contact between the first and second rollers 104, 106 produces x-rays.
The enclosing vessel 102 of the x-ray source 100 has an x-ray window 110
that is substantially transparent to x-rays 112 relative to remaining portions of the
enclosing vessel 102. In other words, the enclosing vessel 102 provides shielding to
substantially block x-rays from exiting the vessel 102 except through the window 110.
The enclosing vessel, including the window 110, maintains a vacuum such that a gas
pressure within the vessel 102 is less than the atmospheric pressure immediately outside
the vessel 102. In an embodiment of the current invention, the enclosing vessel 102 is
constructed to maintain a vacuum less than 10 torr. In an embodiment of the current
invention, the enclosing vessel 102 is constructed to maintain a vacuum greater than 10
torr and less than 10 torr.
In another embodiment, at least one of the first roller 104 and the second
roller 106 has at least two surface regions of different triboelectric materials such that at
least two different x-ray spectra are produced during rolling contact between the first and
second rollers 104, 106. As one should readily recognize, various embodiments of the
current invention can include rollers coated with one, two, three or more types of
triboelectric materials, which could also be coated is selected spatially patterns, to alter
the type of x-ray spectrum produced by the x-ray source 100. In addition, materials that
include one or more selected atomic elements that have desired excited states to enhance
narrow band x-ray emission can also be included. (See also, International Patent
Application number , March 9, 2012 by the same assignee as the
assignee of the current application, the entire content of which is incorporated herein by
reference.)
In an embodiment of the current invention, the drive assembly 108 can
include an electric motor. In some embodiments, the x-ray source 100 can further include
an electrical power storage component that can include at least one of a battery, a
capacitor, or a super capacitor. For example, batteries could be located in the handle 114.
In some embodiments, the x-ray source 100 can further include a photovoltaic element.
In further embodiments, the x-ray source 100 can also include a hand-operated charger.
In some embodiments, the drive assembly can include a hand-operated mechanism (not
shown in the drawings). This can include a hand crank, for example. Such a hand-
operated mechanism can be either in place of, or in addition to, an electric motor.
Other embodiments of the current invention can include three, four or
more rollers. For example, three, four or more rollers can be arranged side-by-side such
that driving at least one roller can cause the remaining rollers to rotate by frictional
contact. These can be thought of as rollers in series. Alternatively, or in addition,
separate pairs or series arrangements of rollers can be provided by other embodiments of
the current invention. For example, one pair of rollers can be arranged next to another
pair of rollers in which each pair of rollers is driven independently of the other pair.
These can be thought of as rollers in parallel. Each roller that is in contact with an
adjacent roller can be constructed to produce x-rays at the intersection. Therefore, in one
embodiment in which there is one pair of rollers, the x-ray source 100 provides a line
source of x-rays. In the case in which there are more than two rollers, the x-ray source
can provide a multiline source of x-rays. In some embodiments, a plurality of rollers can
provide effectively a planar x-ray source.
X-ray pulses can be generated when the pressure is lower than 10 torr
and the contacting materials are a metal vs. a polymer insulator. Also, a contact area of
about 1 mm has been found suitable for producing x-ray pulses. The x-ray pulses can be
on the order of tens of nano seconds, for example.
Since the x-ray source 100 can provide a line, or multiline, x-ray source,
an x-ray imaging system can provide a linear detector selected to correspond to the line
source according to some embodiments of the current invention (see, Figure 6A).
The following provides some examples to help further explain to concepts
of the current invention. The broad concepts of the current invention are not limited to
the particular examples.
EXAMPLES
In an example, two rollers of different materials were selected to exchange
and hold charge after contact. They can be pressed into contact by an external force,
such as, but not limited to springs. A source of mechanical motion such as but not limited
to an electric motor brings the surfaces into relative motion. A particular example of this
embodiment is given by a roller with a metallic surface in contact with a polymer roller.
The x-ray emission from such a system rotating in a vessel held at a pressure of 1x10
Torr of air is provided in Figure 7.
The x-ray flux from contacting rotating rollers can be controlled by the
rotation speed (Figure 8) and it is proportional to the rotation speed up to a tangential
velocity of 80cm/s (see, Inset, Figure 8) according to an embodiment of the current
invention. This speed corresponds to a rotation speed of 200rpm. In general, the x-ray
flux scales with the area of material that is brought into and out of contact per second.
For comparison to our previous work, Figure 8 also includes a compilation of data from
Nature 455, October 23, 2008 and Applied Physics B 99, 2010.
Figure 8 shows the x-ray flux as a function of rotation speed for different
systems. Black squares represent the summary of our previously published results for
peeling scotch tape. Figure of Nature Supplementary is the integrated flux used to obtain
previously published x-ray images by peeling 2cm wide tape at 20cm/s. Figure 2 of
Nature is the integrated flux from peeling 2cm tape at 3.6cm/s. Figure 3 APB is the flux
obtained from peeling a 1.5mm strip of tape at 3.6cm/s. The squares represent data from
peeling 2cm wide scotch tape, showing that this system also scales linearly with rotation
speed. The red dots represent data from a lead roller in contact with tape backing (treated
polyethylene). The inset shows averaged values for representative velocities.
The x-ray spectrum of lead rotating against the backing of a roll of tape
(treated polyethylene) shows the characteristic lead L-lines in Figure 9, upper curve. This
is a clear indication that the lead charges positively relative to the tape backing and acts as
the electron target. Under the same experimental conditions we have measured the x-ray
emission from a roll of tape backing against a roll of sticky-side -out scotch tape (Figure 9
lower curve). The difference in x-ray flux from these two systems demonstrates a method
to control the efficiency with which high energy electrons are converted into x-rays by
changing the atomic weight (Z) of the target material. These results also indicate that one
roller composed of different materials can be used to control the emission as a function of
place of contact.
The x-ray emission from contacting motion can result in bursts of x-rays
(Figure 10). These measurements indicate that the x-ray pulses from a lead roller against
a polyethylene roller are 10-20ns long. This in turn implies a discharge distance of about
11 - 2
lmm and a charge density of about 1x10 eVcm [Nature 455, October 23, 2008]. These
results indicate that this x-ray source is collimated in space and narrow in time.
The spectrum of x-rays emitted from contacting motion can be controlled
by the composition of the materials. Figure 11 shows the spectrum from a polymer roller
against a lead roller compared to the spectrum from the same polymer against a
molybdenum roller. The x-ray emission from the molybdenum roller is dominated by
the characteristic K lines and shows a control of the x-ray energy spectrum. This spectral
distribution is typical for current mammography systems. This source could be useful for
contrast enhanced x-ray imaging. For example by using a roller with half of its surface
covered with one material and the rest in another, resulting in an alternating x-ray
spectrum of different energy synched to the rotation.
An x-ray source according to an embodiment of the current invention can
also be used for phase contrast imaging by using the characteristic x-ray lines of a target
material to narrow the energy spectrum as well as the small source size. Multiple parallel
rollers can act as an array of vertical sources in place of a grid.
An x-ray source according to an embodiment of the current invention can
also be used for x-ray tomography. In particular, an array of different sources can be used
to take multiple x-ray images without having to move the source.
Examples of x-ray images taken with x-ray emission from contacting
rollers are provided in Figures 12A-15.
An x-ray source according to an embodiment of the current invention can
provide a portable, mechanically driven x-ray source that is useful for x-ray imaging
without electricity. Combined with a linear CdTe x-ray detector, for example, it can be
used to obtain energy resolved x-ray imaging. This invention can be used for tomographic
reconstruction such as in digital breast thomosynthesis (Figure 13).
An x-ray source according to an embodiment of the current invention can
also be used for x-ray fluorescence.
The embodiments illustrated and discussed in this specification are
intended only to teach those skilled in the art how to make and use the invention. In
describing embodiments of the invention, specific terminology is employed for the sake
of clarity. However, the invention is not intended to be limited to the specific
terminology so selected. The above-described embodiments of the invention may be
modified or varied, without departing from the invention, as appreciated by those skilled
in the art in light of the above teachings. It is therefore to be understood that, within the
scope of the claims and their equivalents, the invention may be practiced otherwise than
as specifically described.
Claims (28)
1. An x-ray source, comprising: an enclosing vessel; a first roller arranged at least partially within said enclosing vessel; a second roller arranged at least partially within said enclosing vessel and to be in rolling contact with said first roller; and a drive assembly operatively connected to at least one of said first and second rollers, wherein said drive assembly causes said first and second rollers to rotate while in contact to bring portions of said first and second rollers into and out of contact within said enclosing vessel as said first and second rollers rotate, wherein said first roller has a surface at least partially of a first triboelectric material and said second roller has a surface at least partially of a second triboelectric material, said first triboelectric material having a negative triboelectric potential relative to said second triboelectric material, wherein said enclosing vessel is structured to provide a controlled atmospheric environment, and wherein said first triboelectric material, said second triboelectric material and said controlled atmospheric environment are selected such that rolling contact between said first and second rollers produces x-rays.
2. An x-ray source according to claim 1, wherein said enclosing vessel has an x-ray window that is substantially transparent to x-rays relative to remaining portions of said enclosing vessel.
3. An x-ray source according to claim 1, wherein said enclosing vessel is constructed to maintain a vacuum less than 10 torr.
4. An x-ray source according to claim 1, wherein said enclosing vessel is constructed -9 -3 to maintain a vacuum greater than 10 torr and less than 10 torr.
5. An x-ray source according to claim 1, wherein at least one of said first roller and said second roller has at least two surface regions of different triboelectric materials such that at least two different x-ray spectra are produced during rolling contact between said first and second rollers.
6. An x-ray source according to claim 1, wherein said drive assembly comprises an electric motor.
7. An x-ray source according to claim 1, further comprising an electrical power storage component comprising at least one of a battery, a capacitor, or a super capacitor.
8. An x-ray source according to claim 7, further comprising a photovoltaic element.
9. An x-ray source according to claim 7, further comprising a hand-operated charger.
10. An x-ray source according to claim 1, wherein said drive assembly comprises a hand-operated mechanism.
11. An x-ray source according to claim 1, further comprising a third roller arranged at least partially within said enclosing vessel and to be in rolling contact with at least one of said first roller and said second roller, wherein said drive assembly causes said first, second and third rollers to rotate while in contact to bring portions of said at least one of said first and second rollers into and out of contact with said third roller within said enclosing vessel as said first, second and third rollers rotate, wherein said third roller has a surface at least partially of a third triboelectric material, said third triboelectric material having a negative triboelectric potential relative to at least one of said first and second triboelectric materials, and wherein said first triboelectric material, said second triboelectric material, said third triboelectric material and said controlled atmospheric environment are selected such that rolling contact between said first, second and third rollers produces x-rays along at least two roller contacts substantially simultaneously.
12. An x-ray source according to claim 1, further comprising: a third roller arranged at least partially within said enclosing vessel; a fourth roller arranged at least partially within said enclosing vessel and to be in rolling contact with said third roller, wherein said drive assembly is operatively connected to at least one of said third and fourth rollers, wherein said drive assembly causes said third and fourth rollers to rotate while in contact to bring portions of said third and fourth rollers into and out of contact within said enclosing vessel as said third and fourth rollers rotate, wherein said third roller has a surface at least partially of a third triboelectric material and said fourth roller has a surface at least partially of a fourth triboelectric material, said third triboelectric material having a negative triboelectric potential relative to said fourth triboelectric material, wherein said enclosing vessel is structured to provide a controlled atmospheric environment, and wherein said third triboelectric material, said fourth triboelectric material and said controlled atmospheric environment are selected such that rolling contact between said third and fourth rollers produces x-rays.
13. An x-ray source according to claim 1, further comprising a plurality of pairs of rollers arranged at least partially within said enclosing vessel and operatively connected to said drive assembly, wherein each roller of said plurality of pairs of rollers has at least a portion of a surface of a corresponding triboelectric material selected such that rolling contact between each of said plurality of pairs of rollers produces x-rays.
14. An x-ray source according to claim 1, wherein at least one of said first and second triboelectric materials comprises an atomic element in its composition that has an excited quantum energy state that can be excited by electrons traveling from one of said first and second rollers to the other of said first and second rollers, wherein said atomic element emits x-rays having an energy within at least one narrow energy band upon transition from said excited state into a lower energy state such that said x-ray source produces a narrow energy band of x-rays.
15. An x-ray imaging system, comprising: an x-ray source; and an x-ray detector, wherein said x-ray source comprises: an enclosing vessel; a first roller arranged at least partially within said enclosing vessel; a second roller arranged at least partially within said enclosing vessel and to be in rolling contact with said first roller; and a drive assembly operatively connected to at least one of said first and second rollers, wherein said drive assembly causes said first and second rollers to rotate while in contact to bring portions of said first and second rollers into and out of contact along a substantially linear region of contact within said enclosing vessel as said first and second rollers rotate, wherein said first roller has a surface at least partially of a first triboelectric material and said second roller has a surface at least partially of a second triboelectric material, said first triboelectric material having a negative triboelectric potential relative to said second triboelectric material, wherein said enclosing vessel is structured to provide a controlled atmospheric environment, wherein said first triboelectric material, said second triboelectric material and said controlled atmospheric environment are selected such that rolling contact between said first and second rollers produces x-rays along said substantially linear region of contact, said x-ray detector comprises a linear detector constructed and arranged to detect x-rays from said x-ray source.
16. An x-ray imaging system according to claim 15, wherein said enclosing vessel has an x-ray window that is substantially transparent to x-rays relative to remaining portions of said enclosing vessel.
17. An x-ray imaging system according to claim 15, wherein said enclosing vessel is constructed to maintain a vacuum less than 10 torr.
18. An x-ray imaging system according to claim 15, wherein said enclosing vessel is -9 -3 constructed to maintain a vacuum greater than 10 torr and less than 10 torr.
19. An x-ray imaging system according to claim 15, wherein at least one of said first roller and said second roller has at least two surface regions of different triboelectric materials such that at least two different x-ray spectra are produced during rolling contact between said first and second rollers.
20. An x-ray imaging system according to claim 15, wherein said drive assembly comprises an electric motor.
2 1. An x-ray imaging system according to claim 15, further comprising an electrical power storage component comprising at least one of a battery, a capacitor, or a super capacitor.
22. An x-ray imaging system according to claim 21, further comprising a photovoltaic element.
23. An x-ray imaging system according to claim 21, further comprising a hand- operated charger.
24. An x-ray imaging system according to claim 15, wherein said drive assembly comprises a hand-operated mechanism.
25. An x-ray imaging system according to claim 15, further comprising a third roller arranged at least partially within said enclosing vessel and to be in rolling contact with at least one of said first roller and said second roller, wherein said drive assembly causes said first, second and third rollers to rotate while in contact to bring portions of said at least one of said first and second rollers into and out of contact with said third roller within said enclosing vessel as said first, second and third rollers rotate, wherein said third roller has a surface at least partially of a third triboelectric material, said third triboelectric material having a negative triboelectric potential relative to at least one of said first and second triboelectric materials, and wherein said first triboelectric material, said second triboelectric material, said third triboelectric material and said controlled atmospheric environment are selected such that rolling contact between said first, second and third rollers produces x-rays along at least two roller contacts substantially simultaneously.
26. An x-ray imaging system according to claim 15, further comprising: a third roller arranged at least partially within said enclosing vessel; a fourth roller arranged at least partially within said enclosing vessel and to be in rolling contact with said third roller, wherein said drive assembly is operatively connected to at least one of said third and fourth rollers, wherein said drive assembly causes said third and fourth rollers to rotate while in contact to bring portions of said third and fourth rollers into and out of contact within said enclosing vessel as said third and fourth rollers rotate, wherein said third roller has a surface at least partially of a third triboelectric material and said fourth roller has a surface at least partially of a fourth triboelectric material, said third triboelectric material having a negative triboelectric potential relative to said fourth triboelectric material, wherein said enclosing vessel is structured to provide a controlled atmospheric environment, and wherein said third triboelectric material, said fourth triboelectric material and said controlled atmospheric environment are selected such that rolling contact between said third and fourth rollers produces x-rays.
27. An x-ray imaging system according to claim 15, further comprising a plurality of pairs of rollers arranged at least partially within said enclosing vessel and operatively connected to said drive assembly, wherein each roller of said plurality of pairs of rollers has at least a portion of a surface of a corresponding triboelectric material selected such that rolling contact between each of said plurality of pairs of rollers produces x-rays.
28. An x-ray imaging system according to claim 15, wherein at least one of said first and second triboelectric materials comprises an atomic element in its composition that has an excited quantum energy state that can be excited by electrons traveling from one of said first and second rollers to the other of said first and second rollers, wherein said atomic element emits x-rays having an energy within at least one narrow energy band upon transition from said excited state into a lower energy state such that said x-ray source produces a narrow energy band of x-rays.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201161482031P | 2011-05-03 | 2011-05-03 | |
US61/482,031 | 2011-05-03 | ||
PCT/US2012/036310 WO2012154494A2 (en) | 2011-05-03 | 2012-05-03 | Apparatus and method to generate x-rays by contact electrification |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ617143A NZ617143A (en) | 2015-06-26 |
NZ617143B2 true NZ617143B2 (en) | 2015-09-29 |
Family
ID=
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP2705732B1 (en) | Apparatus and method to generate x-rays by contact electrification | |
US9093248B2 (en) | Triboelectric X-ray source | |
Holmlid et al. | Ultradense protium p (0) and deuterium D (0) and their relation to ordinary Rydberg matter: a review | |
Bortoletto | How and why silicon sensors are becoming more and more intelligent? | |
Constable et al. | Mechanisms of x-ray emission from peeling adhesive tape | |
Götzfried et al. | Research towards high-repetition rate laser-driven X-ray sources for imaging applications | |
Akimoto et al. | Generation and use of parametric X-rays with an electron linear accelerator | |
NZ617143B2 (en) | Apparatus and method to generate x-rays by contact electrification | |
Donovan | Xeroradiographic properties of amorphous selenium | |
Camara et al. | Mechanically driven millimeter source of nanosecond X-ray pulses | |
US8897419B1 (en) | Systems and methods for accelerating charged particle beams | |
Abbaszadeh | Indirect conversion amorphous selenium photodetectors for medical imaging applications | |
KR101874029B1 (en) | X-ray source,use thereof and method for producing x-rays | |
Castoldi et al. | X-ray imaging and spectroscopy with Controlled-Drift Detectors: experimental results and perspectives | |
US20230209693A1 (en) | Particle based x-ray source | |
Sauvan | The CMS High Granularity Calorimeter for the High Luminosity LHC | |
Sato et al. | High-speed photon-counting x-ray computed tomography system utilizing a multipixel photon counter | |
Sato et al. | Quasi-monochromatic cerium flash angiography | |
Sato et al. | Enhanced K-edge plasma angiography achieved with tungsten Kα rays utilizing gadolinium-based contrast media | |
Sato et al. | X-ray computed tomography system using a multipixel photon counter | |
Haugen | Charge transport in stabilized A-Se films used in X-ray image detector applications. | |
Sato et al. | Ultra-high-speed embossed radiography system | |
ISOBE et al. | A Pulsed X-ray and Electron Beam Generator | |
Sato et al. | Fluorescent x-ray tomography system for atomic imaging | |
Gouvêa | Lamb Shift in Muonic Helium: X-Ray Detection System |