U.S. patent application number 15/130476 was filed with the patent office on 2017-04-20 for tunable sensing device.
This patent application is currently assigned to National Tsing Hua University. The applicant listed for this patent is National Tsing Hua University. Invention is credited to Wei-Leun FANG, Wei-Cheng LAI.
Application Number | 20170108986 15/130476 |
Document ID | / |
Family ID | 58522982 |
Filed Date | 2017-04-20 |
United States Patent
Application |
20170108986 |
Kind Code |
A1 |
LAI; Wei-Cheng ; et
al. |
April 20, 2017 |
TUNABLE SENSING DEVICE
Abstract
A tunable sensing device includes a substrate, a deformable
dielectric unit and a tunable member. The dielectric unit is
disposed on the substrate and is formed with a receiving space. The
tunable member is received in the receiving space and has a
stiffness tunable by an external electric field or an external
magnetic field.
Inventors: |
LAI; Wei-Cheng; (Taipei
City, TW) ; FANG; Wei-Leun; (Hsinchu City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Tsing Hua University |
Hsinchu City |
|
TW |
|
|
Assignee: |
National Tsing Hua
University
Hsinchu City
TW
|
Family ID: |
58522982 |
Appl. No.: |
15/130476 |
Filed: |
April 15, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04R 19/02 20130101;
G01D 18/00 20130101; H03K 2217/94015 20130101; G01P 15/0802
20130101; G01L 25/00 20130101; G01L 1/148 20130101; H03K 17/975
20130101; H03K 17/962 20130101; G01P 21/00 20130101; G01L 1/142
20130101; H04R 2201/003 20130101 |
International
Class: |
G06F 3/041 20060101
G06F003/041; G06F 3/046 20060101 G06F003/046; G06F 3/044 20060101
G06F003/044 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2015 |
TW |
104134230 |
Claims
1. A tunable sensing device, comprising: a substrate; a deformable
dielectric unit that is disposed on said substrate, and that is
formed with a receiving space; and a tunable member that is
received in said receiving space, and that has a stiffness tunable
by an external electric field or an external magnetic field.
2. The tunable sensing device as claimed in claim 1, further
comprising an electrode unit that includes a first electrode and a
second electrode, which are disposed in said dielectric unit, and
are respectively disposed at two opposite sides of said tunable
member.
3. The tunable sensing device as claimed in claim 2, wherein said
tunable member includes an insulating fluid and a plurality of
particles dispersed in said insulating fluid.
4. The tunable sensing device as claimed in claim 3, wherein said
particles of said tunable member are dielectric particles that are
capable of aligning along the external electric field for
increasing said stiffness of said tunable member.
5. The tunable sensing device as claimed in claim 3, wherein said
particles of said tunable member are magnetic particles that are
capable of aligning along the external magnetic field for
increasing said stiffness of said tunable member.
6. The tunable sensing device as claimed in claim 2, wherein said
tunable member is an electrorheological fluid.
7. The tunable sensing device as claimed in claim 2, wherein said
tunable member is a magnetorheological fluid.
8. The tunable sensing device as claimed in claim 2, wherein said
tunable member is an electroactive polymer.
9. The tunable sensing device as claimed in claim 2, wherein a
maximum capacitance value measured between said first and second
electrodes when said tunable member is applied with the external
electric field or the external magnetic field is larger than a
maximum capacitance value measured between said first and second
electrodes when said tunable member is not applied with the
external electric field or the external magnetic field.
10. The tunable sensing device as claimed in claim 2, wherein a
maximum capacitance value measured between said first and second
electrodes when said tunable member is applied with the external
electric field or the external magnetic field is different from a
maximum capacitance value measured between said first and second
electrodes when said tunable member is not applied with the
external electric field or the external magnetic field.
11. The tunable sensing device as claimed in claim 2, wherein: said
dielectric unit has a bottom portion disposed on said substrate, a
side portion extending from a periphery of said bottom portion away
from said substrate, and a top portion connected to said side
portion and opposite to said bottom portion; said bottom portion,
said side portion and said top portion cooperatively define said
receiving space; and said first electrode is disposed in said top
portion and said second electrode is disposed in said bottom
portion.
12. The tunable sensing device as claimed in claim 11, wherein said
dielectric unit further has at least one through hole penetrating
through said top portion, and being in spatial communication with
said receiving space, and said dielectric unit includes a covering
layer disposed on said top portion and covering said at least one
through hole.
13. The tunable sensing device as claimed in claim 12, wherein said
top portion of said dielectric unit is formed with a recess in
which said second electrode is disposed.
14. The tunable sensing device as claimed in claim 12, wherein said
covering layer is made of a material selected from the group
consisting of parylene C, parylene D, parylene N, silicon dioxide,
silicon nitride, polyimide, metal, and combinations thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority of Taiwanese Patent
Application No. 104134230, filed on Oct. 19, 2015.
FIELD
[0002] The disclosure relates to a tunable sensing device, more
particularly to a tunable sensing device including a tunable member
that has a stiffness tunable by an external electric field or an
external magnetic field.
BACKGROUND
[0003] A conventional sensing device is able to convert physical
quantities generated by an external force into measurable signals,
so that it is possible to identify the interaction between the
sensing device and the external force. Sensing devices, e.g., touch
sensors or triaxial accelerometers are widely used in fields
including robotics, gaming entertainment, biomedical technologies,
etc.
[0004] In regards to touch sensors, measurable signals can
typically be classified as piezoresistance, piezoelectricity,
capacitance, or optical signals. In the case of capacitive sensing
technology, a capacitive touch sensor includes a dielectric member
sandwiched between two metal plates. According to the inverse
relationship between distance and capacitance of the two metal
plates, an external pressing force that causes decreased distance
and increased capacitance between the metal plates allows for
sensing of the external force dimensions.
[0005] Currently available capacitive touch sensors frequently
employ the use of dielectric polymers such as polydimethylsiloxane
(PDMS) to serve as the dielectric member. However, the fixed
properties of the dielectric polymer cause capacitive touch sensors
to have a fixed sensing range. Sensing ranges of these capacitive
touch sensors can vary by adjusting the degree of crosslinking of
PDMS (achieved by changing the proportion of curing agents used in
formation of PDMS), which gives the dielectric member varying
levels of stiffness and changes the sensing range of the capacitive
touch sensor. In other words, when wishing to change the sensing
range of currently available touch sensors, the dielectric member
must be replaced, leading to reduced flexibility and limited
sensing range associated with the existing touch sensors.
SUMMARY
[0006] Therefore, an object of the present disclosure is to provide
a tunable sensing device that can alleviate the drawback associated
with the prior art.
[0007] According to the present disclosure, a tunable sensing
device includes a substrate, a deformable dielectric unit and a
tunable member. The dielectric unit is disposed on the substrate,
and is formed with a receiving space. The tunable member is
received in the receiving space, and has a stiffness tunable by an
external electric field or an external magnetic field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Other features and advantages of the present disclosure will
become apparent in the following detailed description of the
embodiment with reference to the accompanying drawings, of
which:
[0009] FIG. 1 is a partly cross-sectional view of an embodiment of
a tunable sensing device according to the present disclosure;
[0010] FIG. 2 is a schematic view showing an external force applied
to the embodiment;
[0011] FIG. 3 is a schematic view showing the external force
applied to the embodiment, and an external electric field applied
to a tunable member of the embodiment;
[0012] FIG. 4 is a diagram showing capacitance values of the
embodiment versus values of the external force under different
external electric fields; and
[0013] FIG. 5 is a schematic view showing the embodiment applied in
a triaxial accelerometer.
DETAILED DESCRIPTION
[0014] Referring to FIG. 1, an embodiment of a tunable sensing
device 1 according to the present disclosure includes a substrate
2, a deformable dielectric unit 3, a tunable member 4, and an
electrode unit 5.
[0015] The dielectric unit 3 is disposed on the substrate 2 and is
formed with a receiving space 35, in which the tunable member 4 is
received. The dielectric unit 3 has a bottom portion 31 that is
disposed on the substrate 2, a side portion 32 that extends from a
periphery of the bottom portion 31 away from the substrate 2, and a
top portion 33 that is connected to the side portion 32 and
opposite to the bottom portion 31. The bottom portion 31, the side
portion 32 and the top portion 33 cooperatively define the
receiving space 35. The dielectric unit 3 further has at least one
through hole 34. In this embodiment, the dielectric unit 3 has two
through holes 34 that penetrate through the top portion 33, and
that are in spatial communication with the receiving space 35.
Moreover, the dielectric unit 3 includes a covering layer 36 that
is disposed on the top portion 33 and that covers the through holes
34.
[0016] The electrode unit 5 includes a first electrode 51 and a
second electrode 52, which are disposed in the dielectric unit 3,
and are respectively disposed at two opposite sides of the tunable
member 4. To be more specific, the first electrode 51 is disposed
in the top portion 33 of the dielectric unit 3, and the second
electrode is disposed in the bottom portion 31 of the dielectric
unit 3. In certain embodiments, the top portion 33 of the
dielectric unit 3 is formed with a recess 331 in which the second
electrode 52 is disposed, and the second electrode 52 may be spaced
apart from or in contact with the tunable member 4. Likewise, the
first electrode 51 may be spaced apart from or in contact with the
tunable member 4. The through holes 34 are respectively located at
two opposite sides of the recess 311. In certain embodiments, the
covering layer 36 contacts and covers the second electrode 52, such
that the reliability of the tunable sensing device 1 is improved.
It should be particularly pointed out that the position of the
first and second electrodes 51, 52 may be changed as long as the
first and second electrodes 51, 52 are respectively disposed at two
opposite sides of the tunable member 4.
[0017] Specifically, the tunable member 4 enters the receiving
space 35 through the through holes 34, after which the through
holes 34 are sealed with the covering layer 36, such that the
tunable member 4 is sealed in the receiving space 35. The number
and the location of the through holes 34 are not limited to what is
disclosed herein, as long as the tunable member 4 is capable of
being disposed in the receiving space 35 through the through holes
34. In certain embodiments, the top portion 33 of the dielectric
unit 3 may be omitted, and the covering layer 36 seals the
receiving space 35 after the tunable member 4 is disposed in the
receiving space 35. The second electrode 52 is disposed on the
covering layer 36 opposite to the tunable member 4.
[0018] The tunable member 4 has a stiffness that is tunable by an
external electric field or an external magnetic field. In certain
embodiments, the tunable member 4 is a smart fluid, e.g., an
electrorheological fluid (ER-fluid) or a magnetorheological fluid
(MR-fluid), and includes an insulating fluid 41 and a plurality of
particles 42 dispersed in the insulating fluid 41. The insulating
fluid 41 may be silicone oil or mineral oil that have superior
corrosion resistance, stability, insulativity (i.e., low electrical
conductivity) and non magnetism, as well as low permeability. When
the tunable member 4 is the ER-fluid, the particles 42 may be
dielectric particles (e.g., silicon dioxide particles) that are
capable of being polarized by the external electric field, and
aligning along the external electric field for increasing the
stiffness of the tunable member 4. When the tunable member 4 is the
MR-fluid, the particles 42 may be magnetic particles (e.g., iron
powders) that are capable of being polarized by the external
magnetic field, and aligning along the external magnetic field for
increasing the stiffness of the tunable member 4. In certain
embodiment, the tunable member 4 is an electroactive polymer.
[0019] The substrate 2 may be made of silicon. The dielectric unit
3 may be made of a dielectric material, such as silicon dioxide
(SiO.sub.2), silicon nitride (Si.sub.3N.sub.4) polydimethylsiloxane
(PDMS), etc. The covering layer 36 is made of a material selected
from the group consisting of Parylene C, Parylene D, Parylene N,
silicon dioxide, silicon nitride, polyimide, metal, and
combinations thereof.
[0020] In certain embodiments, the substrate 2 is made of silicon,
the dielectric unit 3 is made of silicon dioxide, the tunable
member 4 is the ER-fluid, and the covering layer 36 is made of
parylene C. The tunable sensing device 1 may be made by
microelectromechanical systems (MEMS) techniques, in which the
dielectric unit 3 and the electrode unit 5 are formed by techniques
of etching, hole formation, etc., followed by disposing the tunable
member 4 into the receiving space 35, and subsequently forming the
covering layer 36 on the dielectric unit 3. The manufacturing
techniques of sensing devices are well known in the art, and
detailed descriptions thereof are not further described for the
sake of brevity.
[0021] The tunable sensing device 1 may be used in robotics,
portable apparatuses, touch screens, biomedical technologies, etc.
Referring to FIG. 2, when in use, an external force (F) is applied
to the top portion 33 of the dielectric unit 3, causing the second
electrode 52 and the top portion 33 to be deformed so as to deform
the tunable member 4. A signal change between the first and second
electrodes 51, 52 is measured.
[0022] In certain embodiments, an assembly of the first and second
electrodes 51, 52 and the tunable member 4 is a capacitor, and the
tunable sensing device 1 is used as a capacitive touch sensor. When
the second electrode 52 and the tunable member 4 are deformed, a
distance between the first and second electrodes 51, 52 is changed,
and therefore a capacitance change (i.e., the signal change) can be
measured between the first and second electrodes 51, 52. It should
be noted that the type of signal associated with the external force
(F) applied to the tunable sensing device 1 may be a signal other
than capacitance, such as resistance, optical property, etc. The
type of signal is well known in the art and therefore is not
further described for the sake of brevity.
[0023] It is known that capacitance is inversely proportional to
the distance between the first and second electrodes 51, 52. When a
larger amount of the external force (F) is applied, deformation of
the tunable member 4 is increased, which moves the second electrode
52 and the first electrode 51 closer together, resulting in a
larger capacitance between the first and second electrodes 51, 52.
When the external force (F) exceeds the deformation limit of the
tunable member 4, the tunable member 4 is no longer capable of
being deformed, and thus a maximum capacitance value (i.e.,
saturation capacitance) is measured between the first and second
electrodes 51, 52. In such case, capacitance greater than the
saturation capacitance cannot be measured.
[0024] Referring to FIG. 3 in which the ER-fluid is exemplified as
the tunable member 4, measuring capacitance greater than the
saturation capacitance is possible by applying the external
electric field to the tunable member 4 to adjust the stiffness of
the tunable member 4. Specifically, in certain embodiments, the
first electrode 51 is negatively charged, and the second electrode
52 is positively charged. The particles 42 of the tunable member 4
are polarized to align along the external electric field. When
applying the external force (F) to the tunable sensing device 1,
the polarized particles 42 of the tunable member 4 exert a
resilient force (F.sub.r) against the external force (F). As such,
the stiffness of the tunable member 4 is increased. Therefore, a
larger amount of the external force (F) can be applied to the
tunable sensing device 1 and a greater capacitance can be measured.
In other words, a maximum capacitance value measured between the
first and second electrodes 51, 52 when the tunable member 4 is
applied with the external electric field is different from (e.g.,
larger than) a maximum capacitance value measured between the first
and second electrodes 51, 52 when the tunable member 4 is not
applied with the external electric field. In certain embodiments,
the tunable member 4 is the MR-fluid, and the sensitivity of the
tunable sensing device 1 can be changed by applying the external
magnetic field to the tunable member 4.
[0025] FIG. 4 is a diagram showing the external force applied to
the tunable sensing device 1 shown in FIG. 3 versus capacitance
value measured between the first and second electrodes 51, 52 when
the external electric field is not applied (i.e., 0V) and when the
external electric field (i.e., 1V and 10V) is applied to the
tunable member 4. When the external electric field is not applied
to the tunable member 4 or a smaller external electric field (1V)
is applied to the tunable member 4, saturation capacitance is
reached at an external force of 50 mN. In other words, sensitivity
of the tunable sensing device 1 is in the range of 0 to 50 mN. When
a larger external electric field (10V) is applied to the tunable
member 4, saturation capacitance is reached at an external force of
90 mN. That is, sensitivity of the tunable sensing device 1 is
increased to up to 90 mN.
[0026] It should be particularly pointed out that the signal
measuring mechanism of this disclosure may be changed according to
practical requirements. That is, the electrode unit 5 may be
replaced by other measuring unit, such as piezoresistive,
piezoelectric, magnetoresistive, inductive, paramagnetic,
diamagnetic, optic measuring units, etc.
[0027] FIG. 5 illustrates the tunable sensing device 1 shown in
FIG. 3 being used as a spring 61 in a triaxial accelerometer 6. A
sensing mass member 62 is connected to the spring 61. Sensitivity
of the triaxial accelerometer 6 is controllable by adjusting the
stiffness of the spring 61.
[0028] Besides being used as a touch sensor or in the triaxial
accelerometer, the tunable sensing device 1 may be applied to other
MEMS systems, where a tunable sensing device is needed.
[0029] To sum up, with the tunable member 4 having the stiffness
tunable by the external electric field or the external magnetic
field, sensitivity of the tunable sensing device 1 is tunable
without having to replace the dielectric member as in the
conventional sensing device.
[0030] While the disclosure has been described in connection with
what are considered the exemplary embodiment, it is understood that
this disclosure is not limited to the disclosed embodiment and
variation but is intended to cover various arrangements included
within the spirit and scope of the broadest interpretation so as to
encompass all such modifications and equivalent arrangements.
* * * * *