Method for sensing eyeball movement by using sensor adhered to skin surface of eyelid

Abstract

The invention discloses a method for sensing eyeball movement by using a sensor pasted on the surface of eyelid skin, and belongs to the technical field of sensors, and the method comprises the following steps: S1, pasting sensing units at the position of the upper eyelid skin in an array form; s2, gating is carried out through a row control signal sensing unit and a column control signal sensing unit which are connected with electronic switches in the sensing units; s3, a four-wire resistance test method is adopted to carry out resistance test on the sensing units, and measurement errors caused by wire resistance are avoided; s4, the tiny deformation quantity of the upper eyelid skin is converted into an electric signal through a sensing unit; and S5, acquiring an electric signal of each sensing unit in real time through the single chip microcomputer, and sending the electric signals to a server or a computer for analysis and calculation through wireless transmission to obtain the action condition of the eyeballs. According to the method for sensing the eyeball movement by using the sensor adhered to the skin surface of the eyelid, the eyelid movement with the extremely small amplitude can be captured through the sensor array, and the method is suitable for tracking of fine eye movement.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a method for sensing eye movement using a sensor adhered to the surface of eyelid skin. Background Art

[0002] Current mainstream eye tracking systems utilize conventional CCD / CMOS cameras to capture eye appearance for tracking. Unfortunately, due to the frame rate and limited bandwidth of CCD / CMOS cameras, the tracking frequency of traditional eye tracking systems is typically limited to a few hundred hertz. For example, the latest Tobii Pro Glasses 3 eye tracker has a tracking frequency of 100Hz. Similarly, Pupil Labs has achieved gaze estimation at up to 200Hz. While this modest frequency is sufficient for many common use cases, the peak angular velocity of the human eye during a saccade can reach 700° / s, and the eye acceleration can reach up to 24,000° / s². High-frequency eye tracking can reveal potential information encoded in high-speed and irregular eye movements. For example, in the diagnosis of psychological disorders, increased latency in visually guided saccades can help characterize attention deficit hyperactivity disorder. For example, when studying the early eye movement response of glaucoma, whose mechanism is still unclear, researchers also used eye trackers with a frequency of 300Hz. Unfortunately, achieving accurate eye tracking at frequencies exceeding kilohertz requires a significant increase in camera bandwidth, which is a fundamental obstacle for mainstream CCD / CMOS camera systems. Some high-end eye tracking systems (costing tens of thousands of dollars), such as the EyeLink 1000, can provide eye tracking at 1kHz by utilizing high-speed cameras.

[0003] Using high-frame-rate cameras to collect eye movement data places a considerable computational burden on downstream data processing. Furthermore, camera-based eye tracking systems have a significant weakness: when the subject's head is not stationary, additional computing resources are required to eliminate the effects of head movement, further increasing the cost of the tracking system. Furthermore, in the diagnosis of certain medical conditions (such as glaucoma), eye movement changes vary from person to person, fluctuate day and night, and are affected by daily activities (such as exercise) and circadian rhythms. Therefore, continuous 24-hour monitoring of eye movements is sometimes required, further increasing the difficulty of tracking eye movements using cameras. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for sensing eye movement using a sensor attached to the surface of the eyelid skin. The wearable sensor attached to the surface of the eyelid skin measures the deformation of the eyelid skin and then converts it into an eye movement signal.

[0005] To achieve the above object, the present invention provides a method for sensing eye movement using a sensor attached to the surface of the eyelid skin, comprising the following steps: S1. Paste the sensor units in an array on the upper eyelid skin; S2, the sensing unit is selected by the row control signal and the column control signal connected to the electronic switch in the sensing unit; S3. Use the four-wire resistance test method to test the resistance of the sensor unit to avoid measurement errors caused by wire resistance; S4, converting the tiny deformation of the upper eyelid skin into an electrical signal through a sensing unit; S5. The electrical signal of each sensor unit is collected in real time by the single chip microcomputer, and the electrical signal is sent to the server or computer via wireless transmission for analysis and calculation to obtain the movement of the eyeball.

[0006] Preferably, the sensor array consists of a soft substrate and a plurality of sensing units with the same function, and the sensing units are arranged on the soft substrate.

[0007] Preferably, the flexible substrate is made of a high molecular polymer material.

[0008] Preferably, the polymer material is one or a combination of PET, PI, PDMS, TPU, PU, silica gel, PLA, and PLCL.

[0009] Preferably, the sensing unit includes two strain gauge resistors arranged in an orthogonal arrangement structure.

[0010] Preferably, each of the sensing units further comprises an electronic switch formed by a metal oxide semiconductor field effect transistor.

[0011] Preferably, the sensor array further comprises one or more layers of conductors, and the conductors are disposed adjacent to the flexible substrate.

[0012] Preferably, in step S2, each of the sensing units corresponds to one electronic switch, the control end of the electronic switch in each row is connected to the same row control signal, and the sensing units in each row are uniformly selected by the row control signal, and the control end of the electronic switch in each column is connected to the same column control signal, and the sensing units in each column are uniformly selected by the column control signal.

[0013] Preferably, in step S2, when the electronic switch is made of an N-type semiconductor and the row control signal or the column control signal is high, the electronic switch is turned on; when the electronic switch is made of a P-type semiconductor and the row control signal or the column control signal is low, the electronic switch is turned on.

[0014] Therefore, the present invention adopts the above-mentioned method of sensing eye movement using a sensor attached to the surface of the eyelid skin, which has the following beneficial effects: Compared to traditional optical methods (such as cameras and infrared sensors), this system does not require the user to keep their eyes open for extended periods of time, nor does it require a camera placed in front of the user to monitor their eye movements. Instead, it uses a sensor array to continuously track and monitor eye movements over time. The sensor array can wirelessly transmit eye movement data to a server or computer in real time, analyzing the user's eye movement indicators without disrupting their daily life or sleep, making it more convenient for diagnosing psychological disorders or early screening for glaucoma.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of a method for sensing eye movement using a sensor attached to the surface of eyelid skin according to an embodiment of the present invention; Figure 2 Schematic diagram of the sensor array of the present invention attached to the surface of the eyelid skin; Figure 3 This is an enlarged partial cross-sectional view of the sensor unit of Example 2 of the present invention; Figure 4 Schematic diagram of a unidirectional strain resistor according to an embodiment of the present invention; Figure 5 Schematic diagram of an orthogonal strain gauge resistor according to an embodiment of the present invention; Figure 6 Schematic diagram of 4×3 sensing units according to an embodiment of the present invention; Figure 7 This is a schematic diagram of 4×3 sensing units drawn separately according to an embodiment of the present invention; Figure 8 Schematic diagram of wireless transmission of electrical signals according to the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0019] Example 1 like Figure 1 As shown, the present invention provides a method for sensing eye movement using a sensor attached to the surface of the eyelid skin, comprising the following steps: S1. Paste the sensor units in an array on the upper eyelid skin.

[0020] The sensor array consists of a flexible substrate and several sensing units with the same function. The flexible substrate is made of a very thin polymer material (such as PET, PI, PDMS, TPU, PU, silicone, PLA, PLCL, etc. or one or a combination of materials with similar properties).

[0021] The main part of the sensor array is composed of several sensing units with the same function. The function of each sensing unit is to convert the deformation of its surroundings into an electrical signal (such as resistance change, capacitance change, switch current switching, etc.). These sensing units are arranged on a soft substrate according to a certain pattern to form an array. Figure 2 As shown, the white part represents the soft base material, the blue dot represents a single sensing unit, and the sensing unit can be composed of multiple layers of different materials working together. The thin line is a schematic diagram of the transmission path of the electrical signal (the complete signal transmission path can be composed of multiple layers of wires).

[0022] In this embodiment, the sensing unit is composed of two strain gauge resistors arranged in an orthogonal arrangement. Figure 4As shown in the figure, when the soft substrate is deformed, the cross section and length of the resistor change, so the resistance value of the resistor changes with the deformation. In order to accurately judge the movement of the eyeball, the sensing unit must have a good direction judgment ability, that is, to ensure that the resistor responds to deformation in only one direction (a direction-specific deformation resistor). Just stack two direction-specific deformation resistors in orthogonal directions ( Figure 5 ), a sensing unit that can determine the deformation information (deformation size and direction) around the two resistors can be obtained.

[0023] Each sensing unit is divided into two layers of resistors, upper and lower, which are drawn separately, as shown in Figure 7 Each sensing unit also has an electronic switch (MOS switch) formed by a metal oxide semiconductor field effect transistor (MOSFET).

[0024] The sensor array also includes a conductor, which is arranged adjacent to the soft substrate. Depending on the working principle, it can be arranged as one layer or multiple layers of conductors. Figure 3 The sensing unit is configured as a two-layer conductor structure. A soft substrate is usually provided between the conductor and the skin, and between the conductor and the air. The material formulation of the soft substrate may vary.

[0025] S2. The sensing units corresponding to the turned-on row and column switches are switched on through the MOS switches in the sensing units.

[0026] Each sensor cell corresponds to a MOS switch. For example, in a 4x3 sensor array, each row has three sensor cells, corresponding to three MOS switches. The control terminals of the three MOS switches in each row are connected to a common row control signal (Row1x, Row2x, ...), and all the sensor cells in each row are enabled by this row control signal. When the MOS switches are made of N-type semiconductors, a high row control signal turns the switches on. When the MOS switches are made of P-type semiconductors, a low row control signal turns the switches on. The control terminals of each column of MOS switches are connected to a common column control signal, and all the sensor cells in each column are enabled by this column control signal. The column control signals (Column1x, Column2x, ...) work together with the row control signals to enable sensor cells whose corresponding row and column switches are enabled. In this embodiment, only one sensor cell is enabled at a time (for example, Pixel 11x and Pixel 11y together constitute a single sensor cell).

[0027] S3. Use the four-wire resistance test method to test the resistance of the sensor unit to avoid measurement errors caused by wire resistance.

[0028] S4. The sensor unit converts the tiny deformation of the upper eyelid skin into an electrical signal. The flexible sensor array attached to the eyelid skin can convert the tiny deformation of the eyelid skin into an electrical signal. By reading this electrical signal, the movement of the eyeball can be calculated to achieve the eye tracking function. The working principle of reading the tiny deformation of the skin is as follows: Figure 6 As an example, the flexible sensor array with 4x3 sensing units is shown in the figure. The core of each unit is two orthogonally placed resistors ( Figure 6 (The rectangular objects (x in blue and y in orange, with different colors indicating different layers of the device) are fabricated on a common soft material substrate, and their resistance changes with substrate deformation. The flexible strain sensor array is attached to the skin of the eyelids. When the eye moves, the deformation of the skin near the eye causes the two resistors in the sensing units nearby to change. This resistance change is displayed in real time on a dynamic contour map (or similar amplitude change map) to capture eye movement information.

[0029] S5, collect the electrical signal (resistance data) of each sensor unit in real time through the single chip microcomputer, refer to Figure 8 , the electrical signal is sent to the server or computer via wireless transmission for analysis and calculation to calculate the movement of the eyeball.

[0030] Example 2 In this embodiment, the sensing unit is composed of a capacitor arranged between two layers of conductors. Figure 3 As shown in Figure 1, when the eye moves, the distance between the two layers of conductors near the eye decreases, causing the capacitance near the eye to increase. By scanning and monitoring the changes in the capacitor array in real time, the ability to track eye movements can be achieved.

[0031] Therefore, the present invention adopts the above-mentioned method of sensing eye movement using sensors attached to the surface of the eyelid skin. The sensor array is highly sensitive to tiny skin deformations and can capture extremely small eyelid movements, making it suitable for tracking fine eye movements.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for sensing eye movement using a sensor attached to the surface of the eyelid skin, characterized in that: The following steps are involved: S1. Paste the sensor units in an array on the upper eyelid skin; S2, the sensing unit is selected by the row control signal and the column control signal connected to the electronic switch in the sensing unit; S3. Use the four-wire resistance test method to test the resistance of the sensor unit to avoid measurement errors caused by wire resistance; S4, converting the tiny deformation of the upper eyelid skin into an electrical signal through a sensing unit; S5. The electrical signal of each sensor unit is collected in real time by the single chip microcomputer, and the electrical signal is sent to the server or computer via wireless transmission for analysis and calculation to obtain the movement of the eyeball.

2. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 1, characterized in that: The sensor array consists of a soft substrate and a plurality of sensing units with the same function, and the sensing units are arranged on the soft substrate.

3. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 2, characterized in that: The soft substrate is made of high molecular polymer material.

4. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 3, characterized in that: The polymer material is one or a combination of PET, PI, PDMS, TPU, PU, silica gel, PLA, and PLCL.

5. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 2, characterized in that: The sensing unit includes two strain gauge resistors arranged in an orthogonal arrangement structure.

6. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 5, characterized in that: Each of the sensing units further comprises an electronic switch formed by a metal oxide semiconductor field effect transistor.

7. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 2, characterized in that: The sensor array further includes one or more layers of conductors disposed adjacent to the flexible substrate.

8. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 6, characterized in that: In step S2, each of the sensing units corresponds to one electronic switch, the control ends of the electronic switches in each row are connected to the same row control signal, and the sensing units in each row are uniformly selected by the row control signal, and the control ends of the electronic switches in each column are connected to the same column control signal, and the sensing units in each column are uniformly selected by the column control signal.

9. The method of sensing eye movement using a sensor attached to the surface of the eyelid skin according to claim 8, characterized in that: In step S2, when the electronic switch is made of an N-type semiconductor and the row control signal or the column control signal is high, the electronic switch is turned on; when the electronic switch is made of a P-type semiconductor and the row control signal or the column control signal is low, the electronic switch is turned on.

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