Flexible multifunctional sensor with micropore-cavity structure and preparation method thereof
By constructing a flexible multifunctional sensor with a micropore-cavity structure, the problems of insufficient signal fidelity and complex functional integration were solved, enabling high-fidelity neural signal detection and chemical molecule monitoring, and improving the stability and biosafety of the sensor.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA
- Filing Date
- 2026-01-07
- Publication Date
- 2026-04-17
AI Technical Summary
Current flexible biosensors suffer from insufficient signal fidelity and complex and unreliable functional integration processes, especially in detecting neuronal firing, where it is difficult to achieve high-fidelity and high-spatial-resolution signal detection.
A flexible multifunctional sensor with a micropore-cavity structure is designed. By defining a cavity above the sensing unit and filling it with functional material, and using micropores as the only physical channel, a micropore-cavity structure is constructed to achieve high signal fidelity and stable integration of functional layers.
It significantly improves the fidelity and spatial resolution of electrophysiological signal detection, enhances the long-term stability and biosafety of functional layers, simplifies the process, and is suitable for high-fidelity neural signal recording and highly selective monitoring of specific chemical molecules.
Smart Images
Figure CN121867798A_ABST
Abstract
Description
Technical Field
[0001] This disclosure belongs to the fields of flexible electronics, biosensors and neural interfaces, and relates to a flexible multifunctional sensor with a micropore-cavity structure and its fabrication method. Background Technology
[0002] Flexible biosensors, particularly implantable electrodes (also known as implantable probes) for applications such as neural interfaces, have attracted considerable attention due to their excellent biocompatibility and tissue compliance. These sensors typically comprise a flexible substrate and a sensing unit disposed thereon. However, current flexible biosensors suffer from insufficient signal fidelity.
[0003] When detecting weak physiological signals such as neuronal firing, signal-to-noise ratio and spatial resolution are crucial. Ideally, the sensing unit should form a tight and stable electrical coupling with the target neuron to obtain a signal with an amplitude close to the actual neuronal membrane potential. However, traditional planar or large-area sensing interfaces are prone to non-specific contact with multiple cell or tissue regions, resulting in the acquisition signal being contaminated with a large amount of bioelectrical interference from non-target sources (such as the activity of neighboring neurons and field potential fluctuations) and environmental noise, making it difficult to resolve high-fidelity local neural activity. Summary of the Invention
[0004] This disclosure provides a flexible multifunctional sensor with a microporous-cavity structure and its fabrication method, one of the purposes of which is to solve the problem of insufficient signal fidelity in current flexible biosensors.
[0005] In a first aspect, this disclosure provides a flexible multifunctional sensor with a micropore-cavity structure, comprising: a flexible substrate unit; a sensing unit disposed on the flexible substrate unit; and an encapsulation body disposed on the flexible substrate unit, defining a cavity above the sensing unit, thereby exposing the sensitive area of the sensing unit within the cavity; wherein the top of the encapsulation body has a micropore, which serves as the only physical channel connecting the cavity and the external environment.
[0006] In some alternative embodiments, the package includes: a sidewall surrounding the sensing unit, and a top attached to the sidewall; the sidewall and the top, together with the flexible substrate unit, define the cavity.
[0007] In some alternative embodiments, the height of the cavity in the direction perpendicular to the flexible substrate unit ranges from 1 μm to 100 μm.
[0008] In some alternative implementations, the micropores are positioned directly opposite the sensitive area of the sensing unit.
[0009] In some alternative embodiments, the pore size of the micropores ranges from 0.5 μm to 10 μm.
[0010] In some alternative embodiments, the cavity is filled with a functional material selected from at least one of ion-selective membranes, enzyme layers, and hydrogels.
[0011] In some alternative embodiments, the materials of the flexible substrate unit and the package are selected from at least one of polyimide, polydimethylsiloxane, and parylene C and SU-8 photoresist.
[0012] In a second aspect, this disclosure provides an implantable electrode comprising a flexible substrate layer and at least one flexible multifunctional sensor having a microporous-cavity structure as described in the first aspect; wherein the flexible substrate unit of the flexible multifunctional sensor having a microporous-cavity structure is part of the flexible substrate layer.
[0013] Thirdly, this disclosure provides a method for fabricating a flexible multifunctional sensor with a micropore-cavity structure as described in the first aspect, the method comprising the following steps: Provides a flexible substrate unit with sensing elements; On the flexible substrate unit, a patterned sacrificial layer is formed in the region corresponding to the sensing unit; Encapsulation material is deposited and patterned on the flexible substrate unit and the sacrificial layer to form an encapsulation covering the sacrificial layer; Micropores are formed on the top of the package corresponding to the position of the sensing unit; The sacrificial layer is removed through the micropores, thereby forming a cavity above the sensing unit by the encapsulation body and the flexible substrate unit. The micropores serve as the only physical channel connecting the cavity and the external environment.
[0014] In some alternative embodiments, after removing the sacrificial layer, the method further includes injecting a functional material into the cavity through the micropores and curing it.
[0015] To address the insufficient signal fidelity of current flexible biosensors, this disclosure proposes a flexible multifunctional sensor with a micropore-cavity structure and its fabrication method. The flexible multifunctional sensor scheme of this disclosure defines a cavity above the sensing unit (such as a metal microelectrode or field-effect transistor) by adding a package with a micropore at the top. The micropore serves as the sole physical channel connecting the cavity to the external environment, thereby achieving the following technical effects: 1. Improve the fidelity and spatial resolution of electrophysiological signal detection: By constructing a micropore-cavity structure, an inherent physical spatial shielding capability is provided, which physically restricts the effective contact area between the sensing unit and the external environment to the micropore scale. This forces the sensing interface (the sensitive area of the sensing unit) to establish a local and tight coupling with the target biological source (such as neurons) through tiny holes. This allows the sensor to acquire local signals with smaller spatial resolution without losing sensor area, and significantly attenuates bioelectrical interference and environmental noise from non-directly facing micropore areas. This achieves high-fidelity and high spatial resolution neuronal physiological signal detection, which is especially suitable for recording unit neural signals with extremely high signal-to-noise ratio requirements.
[0016] 2. Compatible with standard processes, facilitating industrialization: The entire manufacturing process of flexible multifunctional sensors is based on mature micro-nano fabrication technology, which is compatible with flexible electronic device production lines, facilitating low-cost, mass production.
[0017] Furthermore, current flexible biosensors may suffer from complex and unreliable functional integration processes. To detect chemical signals such as ions and neurotransmitters, specific functional materials need to be integrated at the sensing interface. Existing methods (such as micro-dot mapping, inkjet printing, and photolithography-assisted patterning) present significant challenges in modifying functional layers for micro-patterning on flexible, miniaturized curved surfaces. Overall modification (such as drop coating and spin coating) can contaminate non-sensing areas; while local modification techniques like micro-dot mapping and inkjet printing face challenges such as poor alignment accuracy, blurred pattern boundaries, and weak adhesion on flexible substrates. More seriously, functional layers directly exposed to dynamic physiological environments are highly susceptible to peeling, degradation, or leakage of active substances, leading to rapid sensor performance degradation and biocompatibility risks.
[0018] A second objective of this disclosure is to address the problem of complex and unreliable functional integration processes in current flexible biosensors. To this end, in some optional embodiments of this disclosure, a cavity is defined above the sensing unit by an encapsulation, and the required specific functional materials (such as ion-selective membranes or enzyme layers) are filled into the cavity to form a functional layer above the sensing unit, which can further achieve the following technical effects: 3. A simple and reliable method for patterned functional integration is provided: By constructing a cavity structure with micropores on the top, a physically confined and patterned containment "mold" is provided for liquid functional materials. This design transforms the complex technical challenges of surface patterning modification into a simple and direct "cavity filling" operation, and ensures precise alignment between the functional layer and the sensing unit, providing a universal and reliable platform for integrating multiple functional materials on flexible devices.
[0019] 4. Enhanced long-term stability and biocompatibility of functional layers: By utilizing the physical constraints of cavities and the flow-limiting effect of micropores, a dual physical encapsulation of functional materials is constructed, forming a semi-closed microenvironment. This effectively prevents leakage, loss, interface peeling, or non-specific diffusion of functional materials within the cavity during use, thereby ensuring the long-term performance stability and biocompatibility of the flexible multifunctional sensor. This greatly extends the in vivo working life and reliability of the flexible multifunctional sensor and improves biocompatibility.
[0020] In summary, this disclosure presents a flexible multifunctional sensor with a microporous-cavity structure and its fabrication method, which helps to solve the problem of insufficient signal fidelity in current flexible biosensors. It can also be further used to address the complexity and unreliability of current functional integration processes for flexible biosensors. The flexible multifunctional sensor solution disclosed herein is applicable to various application scenarios, especially those requiring high-fidelity bioelectrical signal recording (such as neural action potentials and local field potentials) and / or highly selective monitoring of specific chemical molecules (such as ions, glucose, neurotransmitters, and nucleic acids) through patterned functional layers. Attached Figure Description
[0021] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the longitudinal cross-sectional structure of a flexible multifunctional sensor with a micropore-cavity structure according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of a flexible multifunctional sensor with a micropore-cavity structure according to another embodiment of the present disclosure; Figure 3 This is a schematic diagram of a flexible multifunctional sensor with a micropore-cavity structure according to an embodiment of the present disclosure for high-fidelity neuronal signal detection.
[0022] Explanation of reference numerals / symbols in the attached diagram: 100: Flexible substrate unit; 200: Sensing unit; 300: Encapsulation body; 301: Micropore; 400: Cavity; 500: Functional material; 600: Neuron cell. Detailed Implementation
[0023] The specific embodiments of this disclosure will be described below with reference to the accompanying drawings and examples. Those skilled in the art can easily understand the technical problems solved by this disclosure and the resulting technical effects through the content described herein. It is understood that the specific embodiments described herein are merely illustrative of the relevant invention and are not intended to limit the invention. Furthermore, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.
[0024] It should be readily understood that the meanings of “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest sense, such that “on” means not only “directly on something,” but also “on something” including intermediate components or layers existing between the two.
[0025] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship of one element or component to another element or component shown in the accompanying drawings. In addition to the orientations described in the figures, spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90° or otherwise), and the spatial relative descriptive terms used herein may be interpreted accordingly.
[0026] As used herein, the term "layer" refers to a portion of material comprising a region of a certain thickness. A layer may extend over the entirety of an underlying or upper layer structure, or may have a extent smaller than that of the underlying or upper layer structure. Furthermore, a layer may be a region of a homogeneous or heterogeneous continuous structure with a thickness less than that of the continuous structure. For example, a layer may be located between the top and bottom surfaces of a continuous structure, or between any pair of horizontal planes therebetween. A layer may extend horizontally, vertically, and / or along a tapered surface. A substrate may be a single layer, which may include one or more layers, and / or may have one or more layers on, above, and / or below it. A single layer may include multiple layers. For example, a semiconductor layer may include one or more doped or undoped semiconductor layers, and may have the same or different materials.
[0027] As used herein, the term "substrate" refers to the material on which subsequent material layers are added. The substrate itself may be patterned. The material added on top of the substrate may be patterned or may remain unpatterned. Furthermore, the substrate may comprise a wide variety of semiconductor materials, such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, indium phosphide, etc. Alternatively, the substrate may be made of a non-conductive material, such as glass, plastic, or sapphire wafers. Further alternatively, the substrate may have semiconductor devices or circuits formed therein.
[0028] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content described herein, and are not intended to limit the implementation conditions of this disclosure. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effectiveness and purpose of this disclosure, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "above," "first," "second," and "a" used in this specification are merely for clarity of description and are not intended to limit the scope of this disclosure. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this disclosure's implementation.
[0029] It should also be noted that the longitudinal section corresponding to the embodiments of this disclosure can be the section corresponding to the front view direction, the transverse section can be the section corresponding to the right view direction, and the horizontal section can be the section corresponding to the top view direction.
[0030] Furthermore, the embodiments and features described herein can be combined with each other, unless otherwise specified. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.
[0031] refer to Figure 1 , Figure 1 This is a schematic diagram of the longitudinal cross-sectional structure of a flexible multifunctional sensor with a micropore-cavity structure according to an embodiment of this disclosure. Figure 1 As shown, the flexible multifunctional sensor with a micropore-cavity structure disclosed herein includes: Flexible substrate unit 100; The sensing unit 200 is disposed on the flexible substrate unit 100; The package 300 is disposed on the flexible substrate unit 100 and defines a cavity 400 above the sensing unit 200, so that the sensitive area of the sensing unit 200 is exposed in the cavity 400. The top of the package 300 has a micropore 301, which serves as the only physical channel connecting the cavity 400 and the external environment.
[0032] Here, the material of the flexible substrate unit 100 can be selected from at least one polymer such as polyimide, polydimethylsiloxane (PDMS), parylene C, and SU-8 photoresist, and the material of the package 300 can also be selected from at least one polymer such as polyimide, polydimethylsiloxane (PDMS), parylene C, and SU-8 photoresist.
[0033] Here, the sensing unit 200 includes, but is not limited to, a metal microelectrode and a field-effect transistor (FET).
[0034] Here, the package 300 may include: a sidewall surrounding the sensing unit, and a top connected to the sidewall; the sidewall and the top, together with the flexible substrate unit 100 and the sensing unit 200, define a cavity 400.
[0035] Here, the entire flexible multifunctional sensor is based on a flexible substrate unit 100, and the sensing unit 200 is fabricated on the flexible substrate unit 100. The cavity 400 is constructed by the encapsulation body 300 directly above the sensitive area of the sensing unit 200, and the bottom of the cavity 400 is the upper surface (i.e., the sensing interface) of the sensing unit 200.
[0036] In some alternative embodiments, the micropore 301 may be a micropore with a micron-sized aperture formed on the top of the package 300 through which the micropore is formed, with a aperture range of 0.5 μm to 10 μm, and the number of such micropores may be one or more.
[0037] In some alternative implementations, the micro-hole 301 is positioned vertically opposite the sensitive area of the sensing unit 200.
[0038] In some alternative embodiments, the height of the cavity 400 in the vertical direction perpendicular to the flexible substrate unit 100 ranges from 1 μm to 100 μm.
[0039] refer to Figure 2 , Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of a flexible multifunctional sensor with a micropore-cavity structure according to another embodiment of this disclosure. Figure 2 As shown, in some optional embodiments, the cavity 400 is filled with a functional material 500, which is selected from at least one of ion-selective membranes, enzyme layers, and hydrogels. The functional material 500 is used, for example, to realize the detection and transmission of chemical signals such as ions and neurotransmitters.
[0040] refer to Figure 3 The diagram shows a schematic of the flexible multifunctional sensor of this disclosure for high-fidelity neuronal signal detection, wherein neuronal cells 600 are attached to micropores 301.
[0041] The structure of the flexible multifunctional sensor disclosed herein has been described above. This flexible multifunctional sensor utilizes a micropore-cavity structure to improve signal fidelity and functional integration.
[0042] The micropore 301 is used for signal fidelity, and its main function is to form a tight sensing interface (i.e., the interface between the flexible multifunctional sensor and the neuronal cell). In electrophysiological detection, the micropore 301 strictly limits the effective signal collection area of the sensing unit 200 to a very small area directly below the micropore 301, similar to a "pinhole", thereby eliminating most far-field interference and significantly improving the spatial selectivity and signal-to-noise ratio of the signal.
[0043] The cavity 400 is used for functional integration, and its graphic shape (e.g., circle, square, etc.) predefines the pattern of the functional material, enabling the functional material to be formed into a functional layer of a specific shape. In other words, the main function of the cavity 400 is to serve as a patterning of the functional layer. Through the filling-curing process of the functional material, a stable functional layer that is self-aligned with the sensing unit 200 can be easily formed within the cavity 400.
[0044] One embodiment of this disclosure also provides an implantable electrode, which includes a flexible substrate layer and at least one flexible multifunctional sensor with a micropore-cavity structure as described above; wherein the flexible substrate unit 100 of the flexible multifunctional sensor with a micropore-cavity structure may be part of the flexible substrate layer.
[0045] In some alternative embodiments, the implantable electrode may also include bonding pads and metal lines electrically connected between the bonding pads and the flexible multifunctional sensor, the metal lines being embedded within the flexible substrate.
[0046] In some alternative implementations, the implantable electrode can be implanted inside biological tissue to detect neuronal physiological signals in the biological tissue.
[0047] An embodiment of this disclosure also provides a method for fabricating a flexible multifunctional sensor with a micropore-cavity structure as described above, the method comprising the following steps: Step S1: Provide a flexible substrate unit 100 having a sensing unit 200. Here, the sensing unit 200 can be pre-fabricated on the flexible substrate unit 100.
[0048] Step S2: A patterned sacrificial layer is formed on the flexible substrate 100 corresponding to the region of the sensing unit 200. Here, the sacrificial layer can be spin-coated onto the flexible substrate 100 and then patterned through an exposure-development step to form a patterned sacrificial layer of a specific shape to define the cavity region to be formed subsequently. The patterned sacrificial layer can be deposited above and covering the sensing unit 200.
[0049] Step S3: Deposit and pattern encapsulation material on the flexible substrate unit 100 and the sacrificial layer to form an encapsulation body 300 covering the sacrificial layer. The encapsulation material includes, but is not limited to, polymer materials such as polyimide, PDMS, and Parylene C. Here, the encapsulation body 300 can be formed around and above the patterned sacrificial layer, covering the patterned sacrificial layer.
[0050] Step S4: A micro-hole 301 is formed on the top of the package 300 at the position corresponding to the sensing unit 200. Here, the micro-hole 301 can be formed by photolithography-etching process, or by laser drilling or other processes.
[0051] Step S5: The sacrificial layer is removed through the micropore 301, thereby forming a cavity 400 above the sensing unit 200 by the enclosure 300 and the flexible substrate unit 100. The micropore 301 serves as the only physical channel connecting the cavity to the external environment. This results in the following... Figure 1 The flexible multifunctional sensor shown.
[0052] Optionally, the following steps may also be included: Step S6: After removing the sacrificial layer, functional material is injected into the cavity 400 through micropores 301 and cured to form the desired functional layer. Here, the injected functional material includes, but is not limited to, an ion-selective membrane or an enzyme layer. This yields the desired functional layer. Figure 2 The flexible multifunctional sensor shown.
[0053] In summary, this disclosure provides a flexible multifunctional sensor with a micropore-cavity structure and its fabrication method. By constructing a micropore-cavity structure, this disclosure simultaneously addresses key issues related to signal half-fidelity and functional integration. The beneficial effects achieved by this disclosure include, but are not limited to: 1. Achieved high-fidelity, high-spatial-resolution detection of neuronal physiological signals: The microporous structure provides inherent physical spatial shielding capabilities, enabling the sensing unit to acquire local signals with smaller spatial resolution without losing the sensing area. This greatly suppresses bioelectrical interference and environmental noise, making it particularly suitable for recording unit neural signals where extremely high signal-to-noise ratios are required.
[0054] 2. It pioneered a simple and robust patterned functional integration path: the cavity structure transforms the complex technical challenge of surface patterning into a simple "cavity filling" process. This method does not require precise alignment, is easy to operate, and has good repeatability, providing a universal and reliable platform for integrating multiple functional materials on flexible devices.
[0055] 3. Ensures the exceptional stability and safety of the flexible multifunctional sensor: "Cavity confinement" and "micropore current limiting" together constitute a dual physical encapsulation of the functional material, fundamentally eliminating leakage, loss or interface peeling of the functional material during use, greatly extending the in vivo working life and reliability of the flexible multifunctional sensor, and improving biosafety.
[0056] 4. Compatible with standard processes, facilitating industrialization: The entire manufacturing process is based on mature micro-nano fabrication technology, compatible with flexible electronic device production lines, which is conducive to achieving low-cost, mass production.
[0057] Although this disclosure has been described and illustrated with reference to specific embodiments thereof, such descriptions and illustrations are not limiting of this disclosure. It will be readily understood by those skilled in the art that various changes can be made and equivalent elements can be substituted within embodiments without departing from the true spirit and scope of this disclosure as defined by the appended claims. Illustrations may not be drawn to scale. Differences may exist between the technical representation in this disclosure and actual implementation due to variables in the manufacturing process, etc. Other embodiments of this disclosure may exist that are not specifically described. The description and illustrations should be considered illustrative rather than restrictive. Modifications can be made to adapt particular circumstances, materials, composition, methods, or processes to the objectives, spirit, and scope of this disclosure. All such modifications fall within the scope of the appended claims. While the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations can be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of this disclosure. Therefore, unless specifically indicated herein, the order and grouping of operations do not limit this disclosure.
Claims
1. A flexible multifunctional sensor with a micropore-cavity structure, characterized in that, include: Flexible substrate unit; The sensing unit is disposed on the flexible substrate unit; An encapsulation is disposed on the flexible substrate unit and defines a cavity above the sensing unit, so that the sensitive area of the sensing unit is exposed in the cavity; The top of the package has micropores, which serve as the only physical channel connecting the cavity to the external environment.
2. The flexible multifunctional sensor with a micropore-cavity structure according to claim 1, characterized in that, The package includes: a sidewall surrounding the sensing unit, and a top connected to the sidewall; the sidewall, the top, and the flexible substrate unit together define the cavity.
3. The flexible multifunctional sensor with a micropore-cavity structure according to claim 1, characterized in that, The height of the cavity in the direction perpendicular to the flexible substrate unit ranges from 1 μm to 100 μm.
4. The flexible multifunctional sensor with a micropore-cavity structure according to claim 1, characterized in that, The micropores are positioned directly opposite the sensitive area of the sensing unit.
5. The flexible multifunctional sensor with a micropore-cavity structure according to claim 1, characterized in that, The pore size of the micropores ranges from 0.5 μm to 10 μm.
6. The flexible multifunctional sensor with a micropore-cavity structure according to claim 1, characterized in that, The cavity is filled with a functional material selected from at least one of ion-selective membranes, enzyme layers, and hydrogels.
7. The flexible multifunctional sensor with a micropore-cavity structure according to claim 1, characterized in that, The materials of the flexible substrate unit and the package are selected from at least one of polyimide, polydimethylsiloxane, parylene C, and SU-8 photoresist.
8. An implantable electrode, characterized in that, It includes a flexible substrate layer and at least one flexible multifunctional sensor with a micropore-cavity structure as described in any one of claims 1 to 7; wherein the flexible substrate unit of the flexible multifunctional sensor with a micropore-cavity structure is part of the flexible substrate layer.
9. A method for fabricating a flexible multifunctional sensor with a micropore-cavity structure as described in claim 1, characterized in that, Includes the following steps: Provide a flexible substrate unit with sensing elements; On the flexible substrate unit, a patterned sacrificial layer is formed in the region corresponding to the sensing unit; Encapsulation material is deposited and patterned on the flexible substrate unit and the sacrificial layer to form an encapsulation covering the sacrificial layer; Micropores are formed on the top of the package corresponding to the position of the sensing unit; The sacrificial layer is removed through the micropores, thereby forming a cavity above the sensing unit by the encapsulation body and the flexible substrate unit. The micropores serve as the only physical channel connecting the cavity and the external environment.
10. The method according to claim 9, characterized in that, After removing the sacrificial layer, the process further includes: injecting functional material into the cavity through the micropores and curing it.