LU101144B1 - Optical Sensor - Google Patents

Optical Sensor Download PDF

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Publication number
LU101144B1
LU101144B1 LU101144A LU101144A LU101144B1 LU 101144 B1 LU101144 B1 LU 101144B1 LU 101144 A LU101144 A LU 101144A LU 101144 A LU101144 A LU 101144A LU 101144 B1 LU101144 B1 LU 101144B1
Authority
LU
Luxembourg
Prior art keywords
optical waveguide
optical sensor
light
optical
fluorescent dyes
Prior art date
Application number
LU101144A
Other languages
German (de)
Inventor
Wolfgang Kowalsky
Daniel Zaremba
Robert Evert
Original Assignee
Univ Braunschweig Tech
Innovationlab Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Univ Braunschweig Tech, Innovationlab Gmbh filed Critical Univ Braunschweig Tech
Priority to LU101144A priority Critical patent/LU101144B1/en
Priority to PCT/EP2020/055463 priority patent/WO2020178251A1/en
Application granted granted Critical
Publication of LU101144B1 publication Critical patent/LU101144B1/en

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress, in general
    • G01L1/24Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/247Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet using distributed sensing elements, e.g. microcapsules
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress, in general
    • G01L1/25Measuring force or stress, in general using wave or particle radiation, e.g. X-rays, microwaves, neutrons
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/042Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means
    • G06F3/0421Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means by interrupting or reflecting a light beam, e.g. optical touch-screen

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Measuring Fluid Pressure (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

An optical sensor (10) is disclosed which comprises a first optical waveguide (20) and a second optical waveguide (30), the first optical waveguide (20) and the second optical waveguide (30) being separated by a compressible spacer (40), and a layer (35) of at least two fluorescent dyes arranged on the second optical waveguide (30) in differing concentrations at differing locations.

Description

| 92038LU (VZ) Sonnenberg Fortmann LU101144 Title: Optical sensor Cross-Reference to Related Applications
[0001] None Field of the Invention
[0002] The invention relates to an optical sensor for the location of a pressure point.
Prior Art
[0003] Pressure-sensitive touch systems are known in the art. For example, US Patent Application No. US 2014/0210770 (Chen et al, assigned to Corning Incorporated) teaches a pressure sensitive pad for sensing the occurrence of a touch event based on pressure applied at a touch location. The pressure sensitive pad includes a light source system and a detector system that are located at the edges of an optical waveguide. Pressure applied at a touch location on the optical waveguide causes the optical waveguide to bend or flex and leads to a change in the optical paths of the optical waveguide. The changes are detected and used to determine whether a touch event occurred as well as the time evolution of the touch event.
[0004] Another patent application, US Patent Application No. US 2010/0253650 (Dietzel et al, assigned to TNO) teaches an optical sensor for measuring a force distribution and not a single touch event. The sensor has a deformable opto-mechanical layer and its light- responsive properties depend on the degree of deformation of the opto-mechanical layer. Summary of the Invention
[0005] An optical sensor for the detection and measurement of an applied pressure point is disclosed. The optical sensor comprises a first optical waveguide and a second optical waveguide separated by a compressible spacer. A layer of at least two fluorescent dyes is arranged on the second optical waveguide in differing concentrations at differing locations or through a geometrical arrangement along the length of the second optical waveguide. 1
92038LU (V2) Sonnenberg Fortmann LU101144
[0006] In operation, exciting light, i.e. light at an appropriate wavelength for exciting the fluorescent dyes, is coupled into the first optical waveguide of the optical sensor through one of a first end or a second end of the optical sensor. Any pressure placed on the first optical waveguide will cause the first optical waveguide to bend or deflect and the exciting light is coupled into the optical sensor and causes fluorescent emission from the dyes on the second optical waveguide. The fluorescent light is captured by the second optical waveguide and leads to changes in the amplitude and spectrum of the light in the second optical waveguide. The relative intensities of the fluorescent light can be detected by a detector and knowing the position and concentration of the two fluorescent dyes on the second optical waveguide, the location of the pressure point can be calculated.
[0007] It is not necessary to perform any mathematical calculations such as a Fourier transformation of the spectrum to determine the pressure point. The colour spectrum of light transmitted through and/or reflected from the optical sensor will enable the determination of the pressure point by simply measuring the relative intensities of the fluorescent light from the different fluorescent dyes.
[0008] In a first aspect of the optical sensor, the concentration of one of the two fluorescent dyes increases, for example linearly, from the first end of the optical sensor to the second end of the optical sensor and, similarly, in a same aspect or a second aspect, the amount of the another one of the two fluorescent dyes decreases, for example linearly, from the first end of the optical sensor to the second end of the optical sensor. This enables simple calibration of the optical sensor. The fluorescent dyes used include but are not limited to organic dyes like the classes of perylenes, coumarins, metal organic and inorganic dyes as well as fluorescent particles like quantum dots.
[0009] The compressible spacer can be made of a hydrogel.
[0010] The optical sensor has further a light source, such as a laser or LED light producing the exciting light. The wavelength of the exciting light depends on the fluorescent dyes used. In one non-limiting example the exciting light is green or blue light.
[0011] A method of operation of the optical sensor is also disclosed in this document. The method comprises illuminating with light at least one of the first end or the second end of the 2
92038LU (VZ) Sonnenberg Fortmann LU101144 first optical waveguide and coupling the light from the first optical waveguide to cause fluorescing in at least two fluorescent dyes. The light is coupled at the position at which the first optical waveguide is deflected by the application of pressure. The fluorescent light from the at least two fluorescent dyes is coupled by a second optical waveguide and detected bya detector. The detected fluorescent light is analysed in a processor to determine the relative intensities of the fluorescent light from the different fluorescent dyes. Summary of the Drawings
[0012] Fig. 1 shows a bottom view of an optical sensor.
[0013] Fig. 2 shows a side view of the optical sensor.
[0014] Fig. 3 shows a flow diagram with the operation of the optical device.
Detailed Description of the Invention
[0015] The invention will now be described on the basis of the drawings. It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with a feature of a different aspect or aspects and/or embodiments of the invention.
[0016] An optical sensor 10 for the measurement of an applied pressure to a first surface, e.g. an upper surface 12 is shown in Figs.1 and 2.
[0017] The optical sensor 10 comprises a first optical waveguide 20 and a second optical waveguide 30. The first optical waveguide 20 and the second optical waveguide 30 are separated by a compressible spacer 40. The first optical waveguide 20 and the second optical waveguide 30 are multimode waveguides made from a polymer. Different polymers are used as optical waveguides, and these include but are not limited to polymethylmethacrylate (PMMA), Polystyrene (PS), Acrylic Copolymers or cyclic olefin polymers (COP) and copolymer (COC), or transparent silicone like polymethylsiloxane (PDMS).
3
92038LU (V2) Sonnenberg Fortmann LU101144
[0018] The first optical waveguide 20 has a top surface 12 and includes no dyes. In use the first optical waveguide 20 carries the exciting light substantially uniformly over the length of the optical sensor 10. The multimode nature of the first optical waveguide 20 means that coupling to the device can be achieved by simple means, as multimode coupling to a structure with dimensions greater than 100 um is easier than coupling to single mode structures with dimensions in the order of ~10 um. In one aspect of the optical sensor 10, green light is used because green light has less loss along the first optical waveguide made of PMMA.
[0019] The bottom surface 14 of the optical sensor 10 is coated with a layer 35 of a pair of fluorescent dyes A and B. More fluorescent dyes could be used, and the number is not limiting of the invention. The pair of fluorescent dyes A and B have wavelengths which can be separated from one another on optical excitation. Non-limiting examples of such pairs include Coumarin-1 (absorption maximum at 354 nm and emission in range of 420-470 nm) and Coumarin-6 (absorption maximum at 458 nm and emission in range of 500-560 nm) or Perylene (with an absorption between 410-434 nm and emission in range of 436-465 nm) and a different Perylene (with an absorption maximum at 524 nm and emission in range of 539 nm).
[0020] It can be seen from Fig. 1 that the pair of fluorescent dyes A and B are arranged such that the fluorescent dyes form a substantially triangular shape elongated along the length of the optical sensor 10. At first end 16 of the optical sensor 10, the layer 35 is comprised substantially solely of the fluorescent dye A. At the second end 18 of the optical sensor 10, the layer 35 is comprises substantially solely of the fluorescent dye B. In the middle 19 along the length of the optical sensor 10, there is approximately a 50-50 mixture of the fluorescent dye A and the fluorescent dye B. The choice of the fluorescent dyes A and B will depend on the colour of the light in the first optical waveguide 20.
[0021] In one aspect of the optical sensor 10, the compressible spacer 40 is made of a hydrogel, such as but not limited to glycerine. The hydrogel is chosen because it is highly compressible and therefore enables the thickness of the optical sensor 10 to be varied over a large interval. On compression, fluid in the hydrogel moves to the edges of the optical sensor 10 and returns when the pressure is released.
[0022] A light source 50 for the exciting light, such as but not limited to a laser or LED emitting excitation light for the organic dyes used, is coupled to at least one of the first end 16 4
92038LU (V2) Sonnenberg Fortmann LU101144 or the second end 18 of the first optical waveguide 20 of the optical sensor 10 and a detector 60 coupled to at least one of the first end 16 or the second end 18 of the second optical waveguide 30 of the optical sensor 10.
[0023] Applying a pressure to the top surface 12 of the optical sensor 10 means that the blue or green light from the first optical waveguide 10 is coupled through the compressible layer 40 into the second optical waveguide 30 and the layer 30 with the fluorescent dyes. The blue or green light causes the dyes to fluoresce and the fluorescent light is capture by the second optical waveguide and passed to the detector 60 which records the relative intensities of the fluorescent light. The relative intensity indicates the position along the optical sensor 10 at which the pressure is applied, as the amount of the fluorescent dye A and B differs along the optical sensor 10.
[0024] The detector 60 can be either a spectrometer or two colour-sensitive photodiodes which can pass the signals recorded to be processed by a processor 70.
[0025] Fig. 3. shows the optical sensor 10 in operation. In a first step 310, light from the light source 50 is coupled into the first optical waveguide 20. The light is transmitted along the first optical waveguide in step 320. Any pressure applied to the surface at a position of the first optical waveguide 20 means that the first optical waveguide 20 is bent or deflected in step 325 and light in the first optical waveguide 20 at the position is coupled into the compressible spacer 40 and thence to the layer 35 of fluorescent dyes.
[0026] The fluorescent light from the fluorescent dyes is captured in step 330 and will be transmitted along the second optical waveguide 30, as shown by the arrows, to the detector
60. As disclosed above, the position of the application of the pressure in step 330 will change the optical properties of the optical sensor 10 and lead to changes in the spectrum of the detected light. This change of optical properties is processed and analysed in the processor 70 in step 340. The processor 70 stores a previously defined calibration table 75 which is used to determine the location and strength of the applied pressure, which is output in step 350. 5
92038LU (V2) Sonnenberg Fortmann LU101144
Reference Numerals
10 Optical Sensor
12 Top surface
14 Bottom Surface
16 First end
18 Second end
19 Middle
20 First optical waveguide
22 Pressure position
30 Second optical waveguide
35 Layer of at least two fluorescent dyes
40 Compressible spacer
50 Light source
60 Detector
70 Processor 75 Calibration Table 6

Claims (8)

92038LU (Vz) Sonnenberg Fortmann Claims LU101144
1. An optical sensor (10) comprising: a first optical waveguide (20) and a second optical waveguide (30), the first optical waveguide (20) and the second optical waveguide (30) being separated by a compressible spacer (40), and a layer (35) of at least two fluorescent dyes arranged on the second optical waveguide (30) in differing concentrations at differing locations.
2. The optical sensor (10) of claim 1, wherein the concentration of one of the at least two fluorescent dyes increases from a first end (14) of the optical sensor (10) to the second end (14) of the optical sensor (10).
3. The optical sensor (10) of any of the above claims wherein the compressible spacer (40) is made of a hydrogel.
4. The optical sensor (10) of any of the above claims, further comprising a light source (50) coupled to the first optical waveguide (20) at least one of the first end (14) or the second end (16) of the optical sensor (10).
5. The optical sensor (10) of claim 4, wherein the light source is a laser producing one of blue or green light.
6. The optical sensor (10) of any of the above claims, further comprising a detector (60) coupled to the second optical waveguide (30) at least one of the first end (14) or the second end (16) of the optical sensor (10).
7. A method of operation of the optical sensor (10) of one of the above claims, comprising illuminating (310) with light at least one of the first end (12) or the second end (14) of the first optical waveguide (20); applying a pressure (325) at a position (22) to a surface (12) of the first optical waveguide (20) and thereby deflecting the first optical waveguide (20); coupling (330) the light along the first optical waveguide (20) into the optical sensor (10) at the position (20) to cause fluorescence in at least two fluorescent dyes at the 7
92038LU (VZ) Sonnenberg Fortmann . LU101144 deflected position; coupling (330) fluorescing light from the at least two fluorescing dyes in a second optical waveguide (20); detecting (335) the fluorescing light by a detector (60); and processing (340) the detected fluorescing light in a processor (70).
8. The method of claim 7, wherein the illuminating (310) comprises generating green or blue laser light. 8
LU101144A 2019-03-01 2019-03-01 Optical Sensor LU101144B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
LU101144A LU101144B1 (en) 2019-03-01 2019-03-01 Optical Sensor
PCT/EP2020/055463 WO2020178251A1 (en) 2019-03-01 2020-03-02 Optical pressure sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU101144A LU101144B1 (en) 2019-03-01 2019-03-01 Optical Sensor

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LU101144B1 true LU101144B1 (en) 2020-09-02

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114754912B (en) * 2022-04-15 2024-07-12 云南师范大学 Optical fiber carbon quantum dot pressure detection system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4733068A (en) * 1986-04-07 1988-03-22 Rockwell International Corporation Crossed fiber optic tactile sensor
EP0377549A2 (en) * 1989-01-03 1990-07-11 Marcos Y. Kleinerman Remote measurement of physical variables with fiber optic systems
US6965709B1 (en) * 2003-05-14 2005-11-15 Sandia Corporation Fluorescent optical position sensor
US20100253650A1 (en) 2007-09-10 2010-10-07 Nederlandse Organisatie Voor Toegepast-Natuurweten Schappelijk Onderzoek Tno Optical sensor for measuring a force distribution
US20140210770A1 (en) 2012-10-04 2014-07-31 Corning Incorporated Pressure sensing touch systems and methods

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4733068A (en) * 1986-04-07 1988-03-22 Rockwell International Corporation Crossed fiber optic tactile sensor
EP0377549A2 (en) * 1989-01-03 1990-07-11 Marcos Y. Kleinerman Remote measurement of physical variables with fiber optic systems
US6965709B1 (en) * 2003-05-14 2005-11-15 Sandia Corporation Fluorescent optical position sensor
US20100253650A1 (en) 2007-09-10 2010-10-07 Nederlandse Organisatie Voor Toegepast-Natuurweten Schappelijk Onderzoek Tno Optical sensor for measuring a force distribution
US20140210770A1 (en) 2012-10-04 2014-07-31 Corning Incorporated Pressure sensing touch systems and methods

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Effective date: 20200902