Electroencephalogram-controlled optical tweezer system and control method thereof

Abstract

A brainwave-controlled optical tweezers system and its control method are disclosed, comprising an EEG acquisition module, a spatial light modulator module, and a laser module. The EEG acquisition module acquires brainwave signals in real time and preprocesses them using a built-in algorithm before transmitting them to a computer. The spatial light modulator module loads a corresponding grayscale phase map according to computer instructions, converting the fundamental mode light into vortex light with different spiral phase wavefronts, establishing a mapping relationship between attention values ​​and vortex light. The fundamental mode Gaussian light is modulated by the spatial light modulator to generate a vortex beam. The vortex beam is focused and coupled to the objective lens by a laser mirror (DM). After being focused by the objective lens, the vortex light forms an annular vortex light trap on the back focal plane of the slide.

Description

Technical Field

[0001] This invention relates to the fields of light field modulation and brain-computer interface technology, and mainly to a method for directly controlling particles with thoughts through an EEG chip, particularly to an optical tweezers system controlled by EEG waves and its control method. Background Technology

[0002] Currently, people can control mechanical devices (wheelchairs, robotic arms, etc.) using Brain-Computer Interface (BCI) technology. However, due to the influence of external devices, the application scenarios and objects of BCI are limited to a certain extent. For example, mapping human thoughts into electromagnetic holography using BCI devices must be conducted in a microwave anechoic chamber; otherwise, significant interference will lead to experimental failure, which greatly limits the application scenarios of BCI. To date, BCI devices generally control mechanical components to manipulate objects, which can easily cause damage. Moreover, the application objects of BCI systems are almost all macroscopic objects, and their application at the microscopic scale is virtually nonexistent. On the other hand, optical tweezers are a special non-destructive manipulation tool formed by light. Macroscopically, compared with mechanical tweezers, there are no local pressure points, and no mechanical damage is caused. However, most current optical tweezers systems are manually operated, which is relatively passive in the face of emergencies and makes it easy for particles to escape control.

[0003] This invention is the first to propose combining a BCI device with optical tweezers to create a brainwave-controlled optical tweezers system, enabling remote thought-based manipulation of particle movement. Compared to traditional optical tweezers, operators can directly manipulate particles with their thoughts, saving manual operation time and allowing for faster responses to various emergencies. Furthermore, this system uses lasers instead of traditional mechanical components, eliminating localized pressure points and preventing mechanical damage to the object being processed. Operators can use the BCI device to control the laser to pass through transparent barriers and the surface of closed systems (such as cell membranes) to manipulate internal particles (such as organelles), and can also manipulate particles within a sealed sample chamber through its outer wall, achieving truly aseptic operation. This system allows for the application of brain-computer interfaces to objects at the micrometer scale, and is also suitable for manipulating living organisms such as tissues and cells, opening new avenues for the application of brain-computer interfaces at the micrometer scale.

[0004] This application represents the cross-application of optical manipulation technology and BCI technology, and is the first to combine BCI devices with optical tweezers to realize an optical tweezers system controlled by brainwaves. It mainly involves the following two technical backgrounds: 1. Optical tweezers are a special type of non-destructive manipulation tool formed by light. Macroscopically, compared to mechanical tweezers, they do not have localized pressure points and therefore do not cause mechanical damage. Furthermore, optical tweezers can pass unimpeded through transparent barriers, penetrate the surface of closed systems (such as cell membranes), and manipulate internal particles (such as organelles). They can also penetrate the outer wall of a sealed sample chamber to manipulate particles within it, achieving truly aseptic operation. Vortex beams with orbital angular momentum have unique advantages in optical tweezers trapping. When acting on spherical particles, they generate optical forces, such as gradient forces and scattering forces. In a gradient light field, particles are driven towards the center of the optical trap by the intensity gradient force. When the vortex light with orbital angular momentum is absorbed by the particle, its momentum is transferred to the particle, exerting a forward scattering force and causing the particle to rotate around the center of the vortex optical trap. It is worth noting that changing the sign of the topological charge of the vortex light changes the direction of rotation of the microsphere; a positive topological charge results in counterclockwise rotation, and a negative topological charge results in clockwise rotation. Furthermore, optical tweezers can manipulate particles at scales ranging from tens of nanometers to tens of micrometers, and in the field of live biological research, they are currently the only manipulation tool in this scale range. Therefore, we can use the vortex optical traps in optical tweezers to manipulate particles or biological cells.

[0005] 2. Brain-computer interface (BCI) technology is a novel communication and control technology that establishes communication and control between the human or animal brain (or a culture of brain cells) and a computer or other electronic device, independent of conventional brain information output pathways (peripheral nerves and muscle tissue). Electroencephalography (EEG) signals hold a significant position among the various brain signals in BCI systems due to their low cost, non-invasiveness, and relatively low technical difficulty. EEG signals can be non-invasively collected using dry electrodes attached to the scalp and offer multiple EEG patterns. The collected EEG signals can be precisely decoded into corresponding control commands for the external machine using BCI devices, enabling deep interaction between the human brain and the machine.

[0006] The main process of brain-computer interface (BCI) applications based on EEG signals is as follows: Dry electrodes can measure the spontaneous or continuous electrical activity of a large number of cortical neurons. Then, the EEG chip records and preprocesses the EEG signals and transmits them to a computer, which decodes and captures the commands from the brain-computer interface. Changes in the EEG signals are used as communication or control commands between the subject and the computer, such as metasurfaces, speech prostheses, or robotic arms. These EEG signals can be precisely decoded by the computer and converted into corresponding control commands for external devices, thereby achieving deep interaction between the human brain and the machine and enabling thought control.

[0007] 3. This application represents the first cross-application of optical manipulation and BCI technology. Similar technical solutions exist only in other fields, such as remotely controlling a metasurface via brainwaves. It consists of three parts: a sensor, a controller, and an actuator. The sensor is a brainwave module that outputs electrical signals of varying amplitudes based on the level of focus in the brain and transmits these signals to the controller via Bluetooth. The controller comprises a microprogrammed control unit and an output terminal. The controller receives the brainwave signals from the sensor and then inputs the attention signal into the actuator. This signal is divided into four different intervals based on the level of focus, characterized by four thresholds. The controller's output pin is connected to the actuator, and the high and low output voltages correspond to encoded 1 / 0 sequences. The actuator is a metasurface with PIN diodes embedded in its atomic atoms. The diodes correspond to different encoded states in their switching states, and the voltage sequence output by the controller represents different encoded sequences on the metasurface, thereby achieving the scattering and modulation of electromagnetic waves. Using this method, electromagnetic waves can be manipulated directly through real-time responses from the human brain. Summary of the Invention

[0008] To address the problems in the prior art, this application proposes an electroencephalogram (EEG)-controlled optical tweezers system, comprising an EEG acquisition module, a spatial light modulator module, and a laser module. The EEG acquisition module acquires EEG signals in real time, preprocesses them using a built-in algorithm, and then transmits them to a computer. The spatial light modulator module loads the corresponding grayscale phase map according to computer instructions, which transforms the fundamental mode light into vortex light with different spiral phase wavefronts, and establishes a mapping relationship between the attention value and the vortex light. The laser module includes a laser, a reflector, a lens, a half-wave plate, an objective lens, a dichroic mirror, and a filter. The fundamental mode Gaussian light emitted by the laser has its path altered by the reflector, then amplified by the lens. The amplified fundamental mode Gaussian light is then adjusted to the optimal intensity ratio by the half-wave plate and projected onto the spatial light modulator. The spatial light modulator is computer-controlled and loaded with a grayscale phase map. After being modulated by the spatial light modulator, the fundamental mode Gaussian light generates a vortex beam. The vortex beam is focused and coupled to the objective lens by the laser reflector DM. After being focused by the objective lens, the vortex beam forms an annular vortex trap on the back focal plane of the glass slide.

[0009] In one implementation, the EEG acquisition module collects EEG signals through dry electrodes, preprocesses the signals using the built-in algorithm of the TGAM chip, and transmits them to a computer for processing via Bluetooth; wherein the sampling time of the TGAM chip is set to 1 second, and the baud rate of the Bluetooth transmission is set to 57600 bit / s.

[0010] In one implementation, the pure phase spatial light modulator modulates the fundamental Gaussian light into vortex light with corresponding topological charges by loading the phase map of the vortex light; the maximum image frame rate of the spatial light modulator is 60Hz, and the positive and negative signs and magnitudes of the topological charges of the generated vortex light are changed in real time by rapidly switching the grayscale phase map on the SLM, thereby controlling the rotation direction and rotational angular velocity of the particles.

[0011] In one embodiment, the laser is a 532nm high-stability continuous green laser, producing a beam diameter of approximately 2mm, a beam quality factor of less than or equal to 1.5, and an output power of less than or equal to 2.5W.

[0012] This application also relates to a method for controlling an optical tweezers system, comprising the following steps: S1. The EEG acquisition module acquires EEG signals in real time, preprocesses them using a built-in algorithm, and then transmits them to the computer. S2. After receiving the signal, the computer processes it through a program and outputs control commands. S3. The spatial light modulator loads the corresponding grayscale phase map, which transforms the fundamental mode light into vortex light with different spiral phase wavefronts, and establishes the mapping relationship between the attention value and the vortex light. S4. When the topological charge of the vortex light in the sample solution changes, the rotation direction and angular velocity of the particles will also be changed, thus enabling the movement of the particles to be controlled by thought.

[0013] In one implementation, step S3 includes the following steps: S301. The fundamental mode Gaussian light emitted by the laser changes its path through two mirrors M, and then is amplified to 4 times its original size by lenses L1 and L2. S302. The fundamental mode Gaussian light after beam expansion is adjusted to the optimal light intensity ratio by a half-wave plate and then projected onto the spatial light modulator. The spatial light modulator has been controlled by a computer and loaded with a grayscale phase map. The fundamental mode Gaussian light is modulated by the spatial light modulator to generate a vortex beam. S303, the vortex beam is then focused by lenses L3 and L4 and coupled into the objective lens by the laser mirror DM; S304. After being focused by the objective lens, the vortex light forms an annular vortex light trap on the back focal plane of the glass slide.

[0014] In one implementation, step S3 further includes: S305. Light enters the CCD camera through a reflector, and a filter is placed in front of the CCD.

[0015] The above-mentioned technical features can be combined in various suitable ways or replaced by equivalent technical features, as long as the purpose of the present invention can be achieved.

[0016] The electroencephalogram (EEG)-controlled optical tweezers system provided by this invention has at least the following advantages compared with the prior art: (1) This invention patent is the first to propose combining light field modulation technology and BCI technology, opening up a new path for the application of BCI technology in light field modulation.

[0017] (2) Through this invention patent, the operator can remotely control the movement of particles with their thoughts. Compared with traditional optical tweezers, it saves manual operation time and can respond to various emergencies more quickly.

[0018] (3) The size of the object to be manipulated in this invention can reach the micrometer level, and it is also applicable to the manipulation of living organisms such as tissues and cells, filling the gap in the application of BCI at the microparticle scale.

[0019] (4) This invention patent can be easily extended to other applications of mind control or vortex light, such as direct mind control of lasers through BCI devices to pass through transparent barriers and through the surface of closed systems (such as cell membranes) to manipulate internal particles (such as organelles), and can also pass through the outer wall of closed sample chambers to manipulate internal particles, achieving true aseptic operation, which will further expand the application field of brain-computer interfaces. Attached Figure Description

[0020] The invention will now be described in more detail with reference to embodiments and the accompanying drawings. Figure 1 A schematic diagram of an electroencephalogram (EEG)-controlled optical tweezers system; Figure 2 This is a flowchart of the experiment. Figure 3 This is the optical path diagram of the system.

[0021] Laser—laser; M—mirror; L1, L2, L3, L4—lenses; HWP—half-wave plate; SLM—spatial light modulator; Objective—objective lens; Sample—sample; DM—dichroic mirror; Filter—filter. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] This invention provides an electroencephalogram (EEG)-controlled optical tweezers system, comprising: (1) EEG acquisition module: EEG signals are collected through dry electrodes, the built-in algorithm of the TGAM chip is used to preprocess the signals, and the signals are transmitted to the computer via Bluetooth for processing. The sampling time of the TGAM chip is set to 1 second, and the baud rate of Bluetooth transmission is set to 57600 bit / s.

[0024] (2) Spatial Light Modulator Module: Due to the helical phase of the vortex beam, the particles in the vortex optical trap are subjected to a tangential optical trap force, causing them to rotate around the optical axis at the point of maximum light intensity in the vortex optical trap. By switching vortex beams with different topological charges, the rotation direction and angular velocity of the particles in the vortex optical trap can be changed. The pure phase spatial light modulator modulates the fundamental mode Gaussian light into vortex beams with corresponding topological charges by loading the phase map of the vortex beam. The spatial light modulator can achieve a maximum image frame rate of 60Hz, so we can quickly switch the grayscale phase map on the SLM to change the sign and magnitude of the topological charge of the generated vortex beam in real time, thereby controlling the rotation direction and angular velocity of the particles.

[0025] (3) Laser module: including laser, mirror, lens, half-wave plate, objective lens, dichroic mirror, and filter; the laser is a 532nm high-stability continuous green laser, the diameter of the generated beam is about 2mm, the beam quality factor (M2) is less than 1.5, the laser quality is good, and the output power can reach up to 2.5W.

[0026] The rotation of the particles in the vortex optical trap is recorded in real time by a CCD camera and displayed on a computer screen.

[0027] In one embodiment, such as Figure 2 As shown, the first step involves the operator wearing an EEG acquisition module, which collects EEG signals in real time and preprocesses them using a built-in algorithm before transmitting them to a computer via Bluetooth. The second step involves the computer receiving the operator's attention signal, processing it through a program, and outputting control commands. The third step involves the liquid crystal spatial light modulator loading a corresponding grayscale phase map, converting the fundamental mode light into vortex light with different spiral phase wavefronts, establishing a mapping relationship between the attention value and the vortex light. The fourth step involves the operator controlling the movement of the particles by thought when the topological charge of the vortex light in the sample solution changes.

[0028] Experimental optical path as follows Figure 3 As shown, the first step involves the fundamental Gaussian beam emitted by the laser having its path altered by two mirrors M, and then amplified to four times its original size by lenses L1 and L2. The second step involves the amplified fundamental Gaussian beam being adjusted to the optimal intensity ratio by a half-wave plate before being projected onto the SLM (Silicon-Laser Lens). The SLM is computer-controlled and loaded with a grayscale phase map, and the fundamental Gaussian beam is modulated by the SLM to generate a vortex beam. The third step involves the vortex beam being focused by lenses L3 and L4 and then coupled into the objective lens by the laser mirror DM. The fourth step involves the vortex beam being focused by the objective lens, forming a ring-shaped vortex trap on the back focal plane of the slide. The fifth step involves the light beam being incident into the CCD camera through a mirror. Simultaneously, to ensure clearer recording of the rotation of particles within the vortex trap, a filter is placed in front of the CCD.

[0029] The EEG module in this invention is a TGAM chip; however, other EEG devices can also implement this invention, such as a BCI device based on P300.

[0030] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A brainwave-controlled optical tweezers system, characterized in that, It includes an EEG acquisition module, a spatial light modulator module, and a laser module; The EEG acquisition module acquires EEG signals in real time, preprocesses them using a built-in algorithm, and then transmits them to a computer. The spatial light modulator module loads the corresponding grayscale phase map according to computer instructions, which transforms the fundamental mode light into vortex light with different spiral phase wavefronts, and establishes a mapping relationship between the attention value and the vortex light. The laser module includes a laser, a mirror, a lens, a half-wave plate, an objective lens, a dichroic mirror, and a filter. The fundamental mode Gaussian light emitted by the laser has its path altered by the mirror, then amplified by the lens. The amplified fundamental mode Gaussian light is then adjusted to the optimal intensity ratio by the half-wave plate before being projected onto the spatial light modulator. The spatial light modulator is computer-controlled and loaded with a grayscale phase map. After being modulated by the spatial light modulator, the fundamental mode Gaussian light generates a vortex beam. The vortex beam is then focused and coupled into the objective lens by the laser mirror DM. After being focused by the objective lens, the vortex light forms a ring-shaped vortex light trap on the back focal plane of the glass slide. The pure phase spatial light modulator modulates the fundamental Gaussian light into vortex light with corresponding topological charge by loading the phase map of the vortex light. The maximum image frame rate of the spatial light modulator is 60Hz. By rapidly switching the grayscale phase map on the SLM, the positive and negative signs and magnitudes of the topological charge of the generated vortex light are changed in real time, thereby controlling the rotation direction and rotational angular velocity of the particles.

2. The EEG-controlled optical tweezers system according to claim 1, characterized in that, The EEG acquisition module collects EEG signals through dry electrodes, preprocesses the signals using the built-in algorithm of the TGAM chip, and transmits them to a computer for processing via Bluetooth. The sampling time of the TGAM chip is set to 1 second, and the baud rate of the Bluetooth transmission is set to 57600 bit / s.

3. The EEG-controlled optical tweezers system according to claim 1, characterized in that, The laser is a 532nm high-stability continuous green laser, producing a beam diameter of 2mm, a beam quality factor of less than or equal to 1.5, and an output power of less than or equal to 2.5W.

4. A method for controlling an optical tweezers system, characterized in that, Includes the following steps: S1. The EEG acquisition module acquires EEG signals in real time, preprocesses them using a built-in algorithm, and then transmits them to the computer. S2. After receiving the signal, the computer processes it through a program and outputs control commands. S3. The spatial light modulator loads the corresponding grayscale phase map, which transforms the fundamental mode light into vortex light with different spiral phase wavefronts, and establishes the mapping relationship between the attention value and the vortex light. S4. When the topological charge of the vortex light in the sample solution changes, the rotation direction and angular velocity of the particles will also be changed, thus enabling the movement of the particles to be controlled by thought. Step S3 includes the following steps: S301. The fundamental mode Gaussian light emitted by the laser changes its path through two mirrors M, and then is amplified to 4 times its original size by lenses L1 and L2. S302. The fundamental mode Gaussian light after beam expansion is adjusted to the optimal light intensity ratio by a half-wave plate and then projected onto the spatial light modulator. The spatial light modulator has been controlled by a computer and loaded with a grayscale phase map. The fundamental mode Gaussian light is modulated by the spatial light modulator to generate a vortex beam. S303, the vortex beam is then focused by lenses L3 and L4 and coupled into the objective lens by the laser mirror DM; S304. After being focused by the objective lens, the vortex light forms an annular vortex light trap on the back focal plane of the glass slide.

5. The optical tweezers system control method according to claim 4, characterized in that, Step S3 also includes: S305. Light enters the CCD camera through a reflector, and a filter is placed in front of the CCD.

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