U.S. patent application number 12/869465 was filed with the patent office on 2010-12-23 for method for preparing paper that is useful in biomimetic electro-active paper actuators.
This patent application is currently assigned to INHA-INDUSTRY PARTNERSHIP INSTITUTE. Invention is credited to Jae-Hwan Kim.
Application Number | 20100319867 12/869465 |
Document ID | / |
Family ID | 37115262 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100319867 |
Kind Code |
A1 |
Kim; Jae-Hwan |
December 23, 2010 |
METHOD FOR PREPARING PAPER THAT IS USEFUL IN BIOMIMETIC
ELECTRO-ACTIVE PAPER ACTUATORS
Abstract
This invention relates to biomimetic electro-active paper
actuators which are ultra lightweight, have a large deformation
feature, are operated with low power consumption, are remotely
driven by microwaves, and have suitable response speed, which are
comprised of paper wherein micro fibrils of cellulose are arranged
in a predetermined direction, electrodes which are deposited on
both sides of the paper, a film rectenna which receives an electric
field from outside and converts it into direct power, and a PAD
logic circuit (power allocation & distribution) which receives
a signal of direct power and converts/controls it into power
force.
Inventors: |
Kim; Jae-Hwan; (Yeonsu-Gu,
KR) |
Correspondence
Address: |
MARSH, FISCHMANN & BREYFOGLE LLP
8055 East Tufts Avenue, Suite 450
Denver
CO
80237
US
|
Assignee: |
INHA-INDUSTRY PARTNERSHIP
INSTITUTE
Incheon
KR
|
Family ID: |
37115262 |
Appl. No.: |
12/869465 |
Filed: |
August 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11851783 |
Sep 7, 2007 |
7791251 |
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12869465 |
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PCT/KR2005/002176 |
Jul 7, 2005 |
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11851783 |
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Current U.S.
Class: |
162/192 ;
162/197 |
Current CPC
Class: |
H01L 41/193 20130101;
H01L 41/0986 20130101; H01L 41/094 20130101; Y10S 310/80 20130101;
Y10T 29/42 20150115 |
Class at
Publication: |
162/192 ;
162/197 |
International
Class: |
D21F 11/00 20060101
D21F011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2005 |
KR |
10-2005-0022169 |
Claims
1. The method for preparing paper wherein micro fibrils of
cellulose are aligned in a specific direction, comprising steps of:
preparing a cellulose solution by dissolving cellulose pulp, and
aligning micro fibrils in a specific direction by the use of the
centrifugal force of spin-coating, by stretching them with external
force, or by applying electric fields or magnetic fields.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 11/851,783, filed on Sep. 7, 2007, which is a
continuation-in-part of International Application
PCT/KR2005/002176, with an international filing date of Jul. 7,
2005, which claims priority to Korean Application No.
10-2005-0022169, filed Mar. 17, 2005. Each of these applications is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to biomimetic electro-active
paper actuators, which are ultra light, have a large deformation
feature, are operated with low power consumption, are remotely
driven by microwaves and have suitable response speed, and also
relates to a method thereof.
[0004] 2. Description of the Prior Art
[0005] Industrial interest in electro-active polymers (EAP) has
increased because of the possibility of artificial muscles as
functional materials capable of deforming largely. EAP has
flexibility like a muscle as well as it can be deformed largely by
outer stimulation, and has features and functions that other
materials do not. EAP creates applications of artificial muscle
actuators such as for next generation robots, applications in the
entertainment industry or the actuators of a micro air plane. The
application of EAP actuators is broad, and provides utility to many
industry fields. However, since the EAPs developed until now have
limited function, new EAP materials development is essential. There
are many problems with EAP that need to be solved, including
operation force increase, more rapid response, lower power
consumption, and improved durability etc. Particularly, in ultra
light EAP actuators, power supplying is very important when it is
associated with the application device.
[0006] Generally EAP is classified according to operating principle
as either electronic EAP or ionic EAP:
[0007] 1. Electronic EAP: Dr. Zhang of Pennsylvania University has
obtained remarkable piezoelectric phenomenon from an electronic
radiated P (VDF-TrFE) copolymer. When 150 V/.mu.m is applied at low
frequency into the copolymer, about 4% piezoelectric deformation
rate can be obtained and it has an elasticity constant of more than
1 GPa. However, disadvantages are high production cost because of
the irradiation usage and the need for a high actuation voltage.
This is used in acoustic transducer development to be used in
medical probing apparatus, underwater acoustic devices, stereo
speakers and the like. SRI International has developed EAP
actuators based on electrostictive response of dielectric
elastomers covered with a flexible electrode in the presence of an
electric field. Double bow-tie or roll typed linear actuators using
acryl film were utilized in the artificial muscle of biomimetic
robots such as a 6-axials walking robot, a flapping wing of a micro
air plane and the like. However, there are disadvantages that high
voltage of about 200 V/.mu.m must be applied and pre-strain must be
given in lengthwise. NASA Langley research center has developed a
piezoelectric polymer of grafted elastic copolymer that has a
deformation rate of about 4% and a high physical elasticity
constant of 560 MPa at 140 V/.mu.m. The grafted elastic copolymer
comprises grafted polymer composing crystal in backbone having
flexibility. A problem these electronic EAPs have is that they need
a high operating voltage, resulting in that there are many
difficulties in voltage breakdown, packaging, miniaturization,
device design and implementation.
[0008] 2. Ionic EAP: An ionic polymer gel is capable of being
fabricated into actuators exhibiting force and energy density
similar to human muscles. Calvert of Arizona University made an
actuator capable of operating like muscle by stacking cross-linked
poly acryl amide and polyacrilic acid hydrogel alternately between
electrodes. It is bent according to electric field when hydrogel is
placed on water between two electrodes. However, since this
multilayer ionic gel structure needs time for the ion to be
diffused into the gel, the response is slow. Ionomeric
polymer-metal composites (IPMC) are ionic EAP where the polymer net
is bent by cation migration at the electric field applied. Many
researchers including Oguro of Advanced Institute of Science and
Technology in Japan, Shahinpoor of New Mexico University etc. have
investigated the operating principle and functions of IPMC. By
using IPMCs, demonstrations have been made such as a dust wiper, a
gripper, a non-noise swimming robot, an active catheter, a
cilium-like assembled robot, an artificial tactile system similar
to coral reef, and the like. Conducting polymer (CP) is operated by
reversible counter-ion charge and discharge generated during the
redox cycle. Actuators using CP have been developed in many
countries including USA, Japan, Australia, Italy, Spain etc, and
bilayer structures and trilayer structures have been developed with
a stack of CP films and an elastic film without volume deformation.
Sweden Linkopings University has successfully made a robot arm
having an elbow, wrist and 2-4 fingers able to be separately
controlled by using a conducting polymer actuator, and to move a
0.1 mm glass ball about 0.25 mm distance. The actuator using
single-walled carbon nanotubes generates more strain than that of
natural muscle and higher deformation than ferroelectrics having a
high elasticity constant. Macro SWNT actuator such as natural
muscle is a type wherein several billion nanotubes are combined,
and long durability can be achieved because of not needing ion
exchange which reduces lifetime, and because it is operated at low
voltage. These ionic EAPs have disadvantages that operating speed
is slow and there must be an electrolyte and water present while
having the advantage that the operating voltage is low.
[0009] As described above, electronic EAPs developed until now have
rapid response and large deformation rate but need a high operating
voltage, while ionic EAPs can be deformed at low operating voltage
and have elasticity like muscle but response speed is low and
wetness should be kept.
[0010] On the other hand, in applications needing ultra light and
large deformation features such as micro crawling robots, micro air
planes, and animatronic devices, the above-mentioned requirements
are essential. For applications needing ultra light and large
deformation features, EAP needs rapid response, low power
consumption, and good durability. Particularly, since an ultra
lightweight EAP application device cannot carry power batteries, it
is desirable to use a remote power source for reducing the weight
as well as minimizing the power consumption. If a remote power
source is used, EAP applications can be broadened due to the device
being lighter, lower power consumption and improved
performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above and other objects, features and advantages of the
present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0012] FIG. 1 is a schematic diagram showing an electro-active
paper actuator in a state of being bent by an electric field,
wherein electrodes are disposed on both sides of the cellulose
paper,
[0013] FIG. 2 is a schematic diagram showing another state of an
electro-active paper actuator being deformed in a lengthwise
direction, wherein the cellulose paper is disposed in a plane,
[0014] FIG. 3 is a block diagram showing a biomimetic
electro-active paper actuator according to the present
invention,
[0015] FIG. 4 is a perspective view showing an electro-active paper
actuator according to an embodiment of the present invention,
and
[0016] FIG. 5 is a perspective view showing an electro-active paper
actuator according to another embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] The present invention is proposed for solving the above
mentioned problems, and for providing ultra lightweight biomimetic
electro-active paper (EAPap) actuators having a large deformation
rate, low energy consumption, rapid response, durability and remote
controllability. And the present invention provides an operating
method of the actuator that includes microwave power
transmission.
[0018] According to the present invention, the paper actuator is
made of paper comprising cellulose, wherein the paper is made by
arranging micro fibrils in a predetermined orientation and
disposing electrodes on the paper. Therefore, the actuator is
deformed when an electric field is applied.
[0019] In these functional materials, it is very important that the
paper is made by aligning micro fibrils of cellulose in a
predetermined direction. For implementing the paper, a cellulose
solution is prepared by dissolving cellulose pulp using solvents
like a strong alkali, and then micro fibrils are aligned in a
predetermined direction by the use of centrifugal force of
spin-coating, by stretching them with external force, or by
applying electric fields or magnetic fields.
[0020] Various deformations can be obtained according to the method
of depositing electrodes on the paper, and examples are shown in
FIGS. 1-2. FIG. 1 illustrates a bending deformation occurring in a
state that conducting electrodes (2) are deposited on both sides of
the paper (1), one end of the paper being fixed, and an electric
field is applied. FIG. 2 illustrates lengthwise deformation
occurring in another state that paper having two electrodes (2) are
deposited on a plane (3) and an electric field is applied.
[0021] Regarding the detailed operating principle, the crystalline
regions including ordered parts and disordered regions of cellulose
fibrils are deformed by the piezoelectric effect and the ionic
migration effect with an applied electric field. When micro fibrils
are aligned in a specific direction, the piezoelectric effect
occurs due to the crystal structure in the ordered cellulose
regions. It is well known that trees and cellulose have a
piezoelectric effect. Meanwhile, paper is known as an ionic
conductor. In a paper production process, metal ions can be
dissolved into the pulp during paper processing and water molecules
can be included in the paper as absorbed water or free water
molecules. These ions and water molecules migrate to the cathode or
anode according to the applied electric field, resulting in that
deformation occurs.
[0022] A microwave remote principle is shown FIGS. 3-5. When
microwaves arrive at the rectenna (4), the rectenna (4) converts
the received microwaves into dc power. There are many types of
rectennas, e.g., patch type and dipole type, and both can be used.
Since the size of rectenna (4) varies according to frequency,
rectenna size decreases with frequency and can be arranged in a
specific direction. Further, a rectenna can be integrated with an
EAPap actuator because it has a thin film shape. In a dipole
rectenna, microwaves are converted into dc power, and the signal is
applied into EAPap actuator through power conversion/control
circuit of power allocation & distribution (PAD) logic circuit.
PAD (5) implements the principle by supplying power when horizontal
and vertical directional signals are all given using a dual gate
MOSFET. Further, a thin film battery layer (6) can be used by
associating with the actuator such as when microwaves are not
transmitted. At this time, since the electrodes are deposited
separately on both sides of EAPap, the deformation of the paper
actuator can be controlled by controlling the applied voltage. This
method is an operation method for ultra lightweight actuator that
overcomes the limitations of the prior art, and therefore it can
make an EAPap actuator that is ultra lightweight and can be
utilized in various industrial fields. This remote operation is
practical because the required electrical power for the EAPap
actuator is as low as the microwave power threshold that does not
harm human beings. Since a power battery to operate the device is
not needed any more, an ultra lightweight remote operating EAPap
can be implemented as indicated in FIG. 4.
[0023] Although the preferred embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *