A method for preparing a liquid crystal geometric phase device based on a PDMS film substrate
The template method for fabricating liquid crystal geometric phase devices on PDMS thin film substrates solves the problems of heavy weight, poor flexibility, and functional fixation of traditional rigid substrates, achieving lightweight, flexible, and dynamically controllable devices suitable for wearable devices and adaptive optics applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF ELECTRONICS SCI & TECH OF CHINA
- Filing Date
- 2026-04-30
- Publication Date
- 2026-06-02
AI Technical Summary
Traditional liquid crystal geometric phase devices use rigid substrates, resulting in large device weight and poor flexibility, which cannot meet the lightweight and flexible requirements of wearable devices and flexible electronics. Furthermore, their functions are fixed and cannot be stretched or deformed, which limits their application in adaptive optics and dynamic light field modulation. The manufacturing cost is high and it is difficult to scale up.
A template method was used to prepare a PDMS thin film substrate. An alignment layer and liquid crystal solution were spin-coated onto a glass substrate, and then gently peeled off to obtain a complete device. This ensured that the liquid crystal molecules were clearly aligned. Combined with the flexibility and optical transparency of PDMS, dynamic zoom and phase control of the device were achieved.
It achieves lightweight and flexible devices with dynamic zoom and phase adjustment, reduces manufacturing costs, is suitable for large-scale production, and meets the needs of wearable devices and adaptive optics.
Smart Images
Figure CN122131523A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of liquid crystal photonic device fabrication technology, specifically relating to a liquid crystal geometric phase device fabrication technology based on PDMS (polydimethylsiloxane) thin film substrate. It is particularly suitable for scenarios with high requirements for lightweight, flexible, stretchable, and dynamically adjustable devices, such as wearable photonic devices, flexible optical communication modules, adaptive optics systems, holographic displays, and micro zoom devices, and can realize efficient control of the light field and flexible zoom function. Background Technology
[0002] Geometric phase (also known as Pancharatnam-Berry phase) is the path-dependent phase accumulated by a quantum state in the adiabatic evolution of the parameter space. In the field of optics, it can be encoded by the spatial orientation distribution of liquid crystal molecules, thereby realizing the precise control of parameters such as the phase, polarization state, and propagation direction of light. Based on this principle, liquid crystal geometric phase devices have been widely used in many cutting-edge fields such as optical field spatial structure control, holographic display, quantum information processing, and adaptive optics due to their advantages of high efficiency, compactness, and easy integration.
[0003] Currently, most traditional liquid crystal geometric phase devices are fabricated using rigid substrates, such as glass and silicon wafers. While these rigid substrates can ensure the structural stability and phase modulation accuracy of the devices, they have inherent drawbacks: First, they are heavy and have extremely poor flexibility, making them unsuitable for the lightweight and flexible requirements of emerging applications such as wearable devices and flexible electronics, and difficult to integrate with curved surfaces. Second, rigid substrates are not stretchable or deformable, so the functions are fixed after the device is fabricated, and flexible control functions such as dynamic zoom and phase reconstruction cannot be achieved through mechanical deformation, which greatly limits their application range in fields such as adaptive optics and dynamic light field modulation. Third, the fabrication cost of traditional rigid substrates is high, and it is difficult to achieve large-area, low-cost mass production, which is not conducive to the industrialization and promotion of the devices.
[0004] To address the drawbacks of rigid substrates, liquid crystal geometric phase devices with flexible substrates have become a research hotspot. PDMS, as an organosilicon material with excellent flexibility, biocompatibility, and chemical stability, possesses many unique advantages for adapting to liquid crystal geometric phase devices: First, PDMS films have low density and their thickness can be controlled at the micrometer level, significantly reducing the overall weight of the device compared to traditional glass and silicon substrates, enabling lightweight design and meeting the needs of weight-sensitive applications such as wearable photonic devices and micro-optical systems; Second, PDMS has excellent mechanical flexibility and tensile properties, capable of withstanding tensile strains of up to 150% or more, and exhibits strong fatigue resistance, withstanding millions of bending and stretching cycles. Through mechanical deformation such as stretching and bending of the PDMS film substrate, the orientation distribution of liquid crystal molecules can be flexibly controlled, thereby achieving functions such as dynamic zoom and phase adjustment, breaking through the limitations of traditional rigid device functionalities; Third, PDMS films have good optical transmittance, exhibiting high transmittance in a wide spectral range of 240–1100 nm, with negligible birefringence and a refractive index of approximately 1.41 (589). At a wavelength of nm, it can effectively reduce the interference of the substrate on light transmission and ensure the control accuracy of liquid crystal geometric phase devices. Fourth, PDMS fabrication process is simple and low-cost. It can achieve large-area, high-precision patterned fabrication through soft lithography, molding and other methods, and is easy to combine with liquid crystal materials, making it suitable for mass production and facilitating rapid verification and optimization of new device structures. Although PDMS thin film substrates have the above significant advantages, the current composite fabrication based on PDMS thin film substrates and liquid crystal geometric phases still has shortcomings, such as weak bonding between the alignment layer and the PDMS substrate, easy disorder of liquid crystal alignment during stretching, and poor zoom stability, making it difficult to fully utilize the advantages of PDMS thin films in terms of lightweight and stretchable zoom.
[0005] This invention proposes a method for fabricating liquid crystal geometric phase devices based on a PDMS thin film substrate. Unlike previous strategies that involve spin-coating a PDMS solution onto a pre-fabricated liquid crystal device and then peeling it off, this method first uses a template method to prepare a flat, ultra-thin PDMS thin film. This film is then attached to a glass substrate for subsequent fabrication of the liquid crystal geometric phase device. Finally, the liquid crystal device is gently peeled off to obtain a complete liquid crystal device. Under a polarizing microscope, the fabricated thin-film liquid crystal device exhibits a clear alignment of liquid crystal molecules and a relatively clean surface with only a small amount of impurities. Therefore, this research develops a stable and reliable liquid crystal geometric phase device fabrication technology adapted to PDMS flexible thin film substrates, enabling stretching and zooming, which is of great significance for promoting the practical application and multifunctionality of flexible liquid crystal optical devices. Summary of the Invention
[0006] This invention addresses the challenges of rigid substrates being heavy, non-stretchable, and non-deformable, resulting in fixed functions after device fabrication and an inability to achieve flexible control functions such as dynamic zooming and phase reconstruction through mechanical deformation. It provides a method for fabricating liquid crystal geometric phase devices based on PDMS thin film substrates.
[0007] In order to achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: S1. Preparation of PDMS film. The main agent and curing agent are mixed in proportion, and the mixed solution is dropped into a pre-prepared template. Then, vacuum degassing, heating curing, and cooling are performed to obtain the PDMS film.
[0008] S2, PDMS film elasticity test. The elasticity of the PDMS film is tested by repeatedly stretching and releasing it.
[0009] S3. PDMS film is attached to the substrate. The PDMS film is attached to the glass substrate to facilitate the subsequent fabrication of liquid crystal geometric phase devices.
[0010] S4. Fabrication of thin-film liquid crystal geometric phase devices. An alignment solution SD1 is spin-coated onto a glass substrate with a PDMS thin film and annealed to obtain an alignment layer. The substrate is then exposed in a DMD to obtain the desired liquid crystal molecule orientation distribution. Subsequently, liquid crystal solution is spin-coated onto the SD1 layer multiple times and exposed to complete the fabrication of the device.
[0011] S5. Characterization of thin-film liquid crystal geometric phase devices. The PDMS thin film was gently peeled off from the glass substrate to obtain thin-film liquid crystal geometric phase devices, which were then characterized under a polarizing microscope.
[0012] The beneficial effects of this invention are as follows: This invention provides a method for fabricating liquid crystal geometric phase devices based on a PDMS thin film substrate. First, a PDMS thin film is prepared in a pre-designed template to obtain a film of the required thickness and size. Second, PDMS thin films that do not meet the requirements are screened through PDMS thin film elasticity testing. Unlike the previous strategy of spin-coating PDMS solution onto a prepared liquid crystal device and then peeling it off to obtain a flexible liquid crystal device, this invention first uses a template method to prepare a flat, ultra-thin PDMS thin film, then attaches it to a glass substrate for subsequent fabrication of the liquid crystal geometric phase device. Finally, the liquid crystal device is gently peeled off to obtain a complete liquid crystal device. This strategy maximizes the integrity of the thin-film liquid crystal device. Finally, the prepared thin-film liquid crystal device is observed under a polarizing microscope, confirming that the liquid crystal molecules in the thin-film liquid crystal device have good alignment and orientation. In summary, this method provides an efficient and controllable technical route for the fabrication of thin-film liquid crystal geometric phase devices, promoting the multifunctional application of flexible liquid crystal optical devices. Attached Figure Description
[0013] Figure 1 This describes the PDMS thin film preparation process.
[0014] Figure 2 For PDMS film elasticity testing.
[0015] Figure 3 This describes the fabrication process for liquid crystal geometric phase devices based on PDMS thin films.
[0016] Figure 4 This describes the performance characterization of thin-film liquid crystal geometric phase devices. Detailed Implementation
[0017] This invention addresses the problems of rigid substrates being heavy, liquid crystal geometric phase devices (JDPDs) fabricated on rigid substrates being non-stretchable and non-deformable, having fixed functions after fabrication, and being unable to achieve flexible control functions such as dynamic zooming and phase reconstruction through mechanical deformation, as well as the difficulty in large-area, low-cost mass production. The proposed JDPDs based on PDMS thin-film substrates effectively avoids these problems and maximizes the integrity of the thin-film liquid crystal devices. To enable those skilled in the art to better understand this invention, specific embodiments are described below. It should be noted that these descriptions are not intended to limit the scope of protection of this invention. Any obvious changes or modifications made by those skilled in the art without departing from the principles of this invention should be considered to fall within the scope of protection defined by the claims of this invention. All creations based on the concept of this invention are protected by this invention.
[0018] As a fabrication technology, this method for fabricating liquid crystal geometric phase devices based on PDMS thin film substrates includes the following steps: S1. Prepare PDMS film using template. Figure 1 The preparation process of PDMS film was demonstrated. First, the PDMS main agent and curing agent were mixed evenly at a volume ratio of 10:1. Then, the mixed solution was dropped into a pre-prepared template. The template with the PDMS mixture was placed in a vacuum chamber for vacuum degassing. Then, it was heated on a hot plate at 60°C for two hours. After cooling, the prepared PDMS film was removed from the template.
[0019] S2. Perform elasticity testing on the prepared PDMS film. Good elasticity of the PDMS film is a prerequisite for achieving functions such as zoom in thin-film liquid crystal geometric phase devices. Figure 2The process of testing the elasticity of PDMS films is demonstrated. By measuring the dimensions of the original PDMS film, stretching and releasing it, and observing whether the dimensions of the restored PDMS film have changed compared to the original PDMS film, PDMS films with good elasticity are selected.
[0020] S3. Attach the PDMS film to the substrate. Attach the highly elastic PDMS film to the glass substrate, and try to remove air bubbles between the PDMS film and the glass substrate to facilitate the subsequent fabrication of thin-film liquid crystal devices.
[0021] S4. Fabricate thin-film liquid crystal geometric phase devices. Figure 3 This paper demonstrates the fabrication process of a liquid crystal geometric phase device based on a PDMS thin film. An alignment solution SD1 was spin-coated onto a glass substrate with a PDMS thin film at a rate of 3000 rpm, and annealed at 100°C for 7 minutes to obtain an alignment layer. The substrate was then exposed to a DMD to obtain the desired liquid crystal molecule orientation distribution. Next, a liquid crystal solution was spin-coated onto the SD1 layer at a rate of 3000 rpm, and cured under a UV lamp for one minute to obtain a liquid crystal layer. This spin-coating and UV curing process was repeated multiple times to ensure the thickness of the liquid crystal device met the half-wave condition at 532 nm, thus completing the fabrication of the thin-film liquid crystal geometric phase device.
[0022] S5. Characterize the thin-film liquid crystal geometric phase device. The PDMS film is gently peeled off from the glass substrate to obtain the thin-film liquid crystal geometric phase device, which is then observed under a polarizing microscope. Figure 4 The results of observations of thin-film liquid crystal geometric phase devices under a polarizing microscope are presented. The results show that the liquid crystal molecules in the thin-film liquid crystal device have good alignment and orientation, and the surface of the device is relatively clean, with only a small amount of dust and other impurities present.
[0023] It should be noted that any modifications and improvements can be made to the above embodiments without departing from the scope defined by the claims of this invention. Therefore, the claimed technical solutions should not be limited to any particular embodiment.
Claims
1. A method for fabricating a liquid crystal geometric phase device based on a PDMS thin film substrate, characterized in that, Includes the following steps: S1. Preparation of PDMS film: PDMS main agent and curing agent are mixed in proportion, the mixed solution is dropped into a preset template, and the mixture is subjected to vacuum degassing, heating curing and cooling steps in sequence to obtain PDMS film; S2, PDMS film elasticity test: By repeatedly stretching and releasing the PDMS film, the film size before and after stretching is compared to screen out PDMS films with qualified elasticity; S3. PDMS film bonding to the substrate: The qualified PDMS film selected in step S2 is bonded to the glass substrate, and air bubbles between the PDMS film and the glass substrate are removed. S4. Fabrication of thin-film liquid crystal geometric phase device: An alignment solution SD1 is spin-coated onto a glass substrate with a PDMS thin film and then annealed to obtain an alignment layer; The substrate with the alignment layer is exposed in a DMD to obtain the preset liquid crystal molecule orientation distribution; the liquid crystal solution is spin-coated multiple times on the alignment layer and then exposed and cured to make the device thickness meet the half-wave condition at the preset wavelength, thus completing the device fabrication. S5. Characterization of thin-film liquid crystal geometric phase device: The PDMS thin film was peeled off from the glass substrate to obtain a complete thin-film liquid crystal geometric phase device, which was then characterized using a polarizing microscope.
2. The preparation method according to claim 1, characterized in that, In step S1, the volume ratio of the PDMS main agent to the curing agent is 10:
1.
3. The preparation method according to claim 1, characterized in that, In step S1, the heating and curing conditions are 60°C for 2 hours.
4. The preparation method according to claim 1, characterized in that, In step S4, the spin-coating orientation solution SD1 is applied at a rate of 3000 rpm, and the annealing condition is annealing at 100°C for 7 minutes.
5. The preparation method according to claim 1, characterized in that, In step S4, the spin coating rate of the liquid crystal solution is 3000 rpm, and the UV curing time is 1 minute.
6. The preparation method according to claim 1, characterized in that, In step S4, the preset wavelength is 532 nm, and the half-wave condition is the requirement for the liquid crystal half-wave phase to be adapted to the device thickness at a wavelength of 532 nm.
7. The preparation method according to claim 1, characterized in that, In step S2, the criterion for determining the elasticity qualification is: after repeated stretching and releasing, the restored size of the PDMS film is consistent with the original size, and there is no permanent deformation.
8. The preparation method according to claim 1, characterized in that, In step S1, the thickness of the PDMS film is in the micrometer range, the transmittance is not less than 90% in a wide spectral range of 240~1100 nm, and the refractive index is 1.41±0.02 (at a wavelength of 589 nm).
9. The preparation method according to claim 1, characterized in that, In step S4, the number of spin coatings of the liquid crystal solution is 2 to 5 times to ensure that the liquid crystal layer thickness is uniform and meets the half-wave condition.
10. The preparation method according to claim 1, characterized in that, In step S5, the core indicators of the characterization are: clear alignment of liquid crystal molecules, clean device surface, and impurity content that does not affect the device's light field modulation performance.