Preparation method for manufacturing arbitrarily customized circuit on various medical hoses

Abstract

The invention discloses a preparation method for manufacturing any customized circuit on various medical instrument hoses, and belongs to the field of micro-nano manufacturing. Compared with other preparation methods in the prior art, the method has the advantages that the operation is repeated and universal, the production cost is low, the patterning on the taper edge with the minimum curvature radius is different from the traditional standard planar micro-nano processing technology, for example, the patterning can only be carried out on the plane by using the traditional photoetching and film coating, and the manufacturing cost is low. And operation cannot be carried out on the surface of the hose with the extremely small curvature radius. According to the invention, the preparation of any customized circuit can be realized on the surfaces of various medical instrument hoses. By means of the method, flexible sensors can be integrated on the surfaces of any customized circuits manufactured on the surfaces of hoses of various medical instruments, such as indwelling needles, gastrointestinal endoscope tubes, catheters, endoscopes, drainage tubes and other instruments with flexible tube cavity structures.

Description

Technical Field

[0001] This invention relates to a method for fabricating custom circuits on various types of medical tubing, belonging to the field of micro-nano manufacturing. Background Technology

[0002] In the field of micro-nano manufacturing, flexible photolithography for curved edges is a key technology that is both challenging and cutting-edge. With the rapid development of minimally invasive interventional medical devices, especially the increasing demand for surface functionalization in precision instruments such as interventional catheters and drainage tubes, the need for high-precision micro-nano pattern fabrication on curved substrates is becoming increasingly prominent. Traditional photolithography is limited by the processing paradigm of rigid planar substrates, making it difficult to achieve uniform adhesive layer coverage and accurate pattern transfer on the high-curvature surfaces (curvature radius typically 0.5-5 mm) unique to medical flexible tubes, resulting in core problems such as edge distortion and reduced resolution. To address the technical requirements for fabricating micro-nano structures on the surfaces of various medical flexible tubes, this study developed a complete solution based on traditional photolithography and flexible mask water transfer printing technology, coupled with a self-designed rotating fixture adapted for rotational coating within a coating chamber. This solution optimizes the traditional photolithography process to prepare flexible masks and combines innovative water transfer printing and rotational coating technologies to achieve precise patterning of curved substrates. Summary of the Invention

[0003] The purpose of this invention is to provide a method for fabricating custom circuits on various medical tubing using a flexible photolithography mask. This method is simple to operate, requires minimal equipment, has low production costs, and can be mass-produced. Using this method, custom circuits fabricated on the surface of various medical device tubing, such as those on indwelling needles, gastrointestinal endoscope tubes, catheters, endoscopes, and drainage tubes—devices with flexible lumen structures—can integrate flexible sensors on their surfaces.

[0004] To solve the technical problem of this invention, the proposed technical solution is: a method for fabricating arbitrary custom circuits on various types of medical tubing, comprising the following steps:

[0005] Step 1: Clean the silicon wafer surface, prepare a sacrificial layer on the silicon wafer surface, then spin-coat photoresist, and use ultraviolet lithography to pattern the photoresist to obtain a patterned photoresist thin film mask.

[0006] Step 2: Place the sample into the sacrificial layer dissolving solution. After the dissolving solution slowly etches and dissolves the corresponding sacrificial layer, the patterned photoresist film mask will be released and float on the surface of the etching solution.

[0007] Step 3: Using a transfer substrate, retrieve the patterned photoresist film mask. First, transfer it to a container containing deionized water. After the deionized water slowly dilutes the residual etching solution on the surface of the film mask, retrieve the patterned photoresist film mask again using the transfer substrate. Finally, transfer it to a container containing a viscous solution. Slowly place the medical tubing into the viscous solution, align it with the flexible photoresist film, and lift and adhere it, completely and shape-preservingly wrapping the flexible photoresist mask onto the surface of the medical tubing. Then, place it in an oven to dry.

[0008] Step 4: After masking the exposed portion of the medical tubing with tape, place it in the coating chamber for rotational physical vapor deposition (PVD). Once coating is complete, remove it from the chamber, peel off the tape mask from the flexible photoresist mask, and the complete custom circuit is successfully fabricated on the medical tubing.

[0009] Furthermore, in step one, after cleaning the silicon wafer using an oxygen plasma machine, a layer of sacrificial metal such as Ni, Cr, or Al is sputtered using a magnetron sputtering machine, or a water-soluble polymer is spin-coated.

[0010] Furthermore, in step one, the ultraviolet lithography technique uses polyimide photoresist, which can be either positive or negative. The photoresist is first spin-coated onto the silicon substrate at 1000 rpm / min for 10 s, then spin-coated at 3500 rpm / s for 30 s. This is followed by a series of steps including pre-baking, exposure, development, and post-baking.

[0011] Furthermore, in step one, the polyimide photoresist is a series of photosensitive polyimide materials, such as the P3000 series photosensitive positive polyimide material or the P2000 series negative photosensitive polyimide photoresist.

[0012] Furthermore, in step one, the pre-baking parameters require constant heating at 120 ℃ for 3 min, exposure using a 365nm ultraviolet light source, and post-baking requires slow heating up to 200 ℃, followed by constant heating for 60 min.

[0013] Furthermore, in step two, the solution used needs to slowly dissolve the corresponding sacrificial layer material until the flexible photoresist film floats on the surface of the solution.

[0014] Furthermore, in step three, the flexible photoresist film needs to be transferred twice using the transfer substrate. The purpose of the first transfer is to clean the surface of the flexible photoresist film of any residual solution, and the purpose of the second transfer is to give the surface of the flexible photoresist film a certain degree of adhesion.

[0015] Furthermore, in step three, a water transfer printing method is used to transfer the flexible photoresist film onto the surface of the medical tubing intact and shape-preservingly through water pressure.

[0016] Furthermore, in step three, the medical tubing is placed in a sterile oven to dry, so that the flexible photoresist film is tightly bonded to the medical tubing.

[0017] Furthermore, in step four, a self-made rotating table clamp is used to place the medical tubing into the clamp, allowing for 360-degree rotation and coating without any blind spots.

[0018] The beneficial effects of this invention are as follows: A flexible photoresist mask is fabricated using traditional ultraviolet lithography technology. The resolution of this mask is entirely determined by planar lithography, reaching the nanometer scale. After being cut to the required size for the device, the sacrificial layer is dissolved, and a water transfer method is used to transfer the fabricated flexible mask intact and shape-preservingly onto the surface of a medical catheter. Finally, a 360-degree physical vapor deposition coating is performed using a self-designed rotating fixture. This method offers advantages such as simple process, high speed and efficiency, stable structure, good consistency, and mass replication capability for fabricating arbitrary custom circuits on various medical catheters.

[0019] Furthermore, compared to the previous patent, "A Method for Fabricating Conductive Paths and Electrodes on Acupuncture Needles," this patent has significant advantages. The previous patent involved uniformly coating the acupuncture needle surface with photoresist, wrapping a photolithographically fabricated PDMS flexible mask, and then performing curved surface exposure. In contrast, all exposure steps in this patent are performed in a planar plane. Planar exposure achieves higher resolution (depending on the polyimide photoresist, the maximum achievable resolution after photolithography is approximately 3μm) and a near 100% product yield. On a curved surface, the resolution is less than 30μm, and the yield is less than 50%. Moreover, the fabrication steps in the previous patent were more complex and prone to errors, resulting in a low yield. This patent, however, has a very simpler process; the sample prepared by a single photolithography step can be directly manufactured through a coating process. Finally, compared to the PDMS flexible mask (approximately 50μm) in the previous patent, the polyimide photoresist flexible mask prepared in this patent is thinner (only 5μm), softer, and less prone to deformation.

[0020] This invention can be applied to flexible tubes of various shapes. We cut a flexible mask on a plane according to the shape of the tube, allowing the film to adhere to the tube. This was almost impossible in the previous patent because PDMS itself lacks sufficient adhesiveness. While it can self-adhere to regular cylindrical shapes, irregular shapes result in loose structures due to poor adhesion of the cut PDMS flexible mask, leading to failure in curved surface lithography. Using adhesive materials as a bonding layer is also undesirable, as it significantly affects light transmittance during lithography. Therefore, this invention can be applied to flexible tubes of various shapes, and because the preparation steps are simple and the process is easy to standardize, it can be automated using machines to replace manual labor, facilitating industrialization.

[0021] Firstly, the core of this patent lies in the use of photosensitive polyimide photoresist for traditional planar photolithography. This type of photoresist can be peeled off at high temperatures (>200℃) during post-baking to become a complete and independent flexible mask (the photoresist used in integrated circuit manufacturing only serves as a patterned protective layer attached to the silicon wafer surface and cannot be peeled off to form a film independently). It has both the extremely high resolution brought by photolithography and the thin film characteristics of polymer materials such as polyimide, so it can be peeled off from the substrate and form a film independently.

[0022] Secondly, the patent also uses a specially customized rotary sputtering fixture (the coating instruments used in integrated circuit manufacturing are all planar coating instruments), which can coat medical tubes wrapped with flexible masks in 360° without dead angles.

[0023] Using the method of this invention, any customized circuit manufactured on the surface of various medical device tubing, such as indwelling needles, gastrointestinal endoscope tubes, catheters, endoscopes, drainage tubes, and other devices with flexible lumen structures, can integrate flexible sensors on their surface. After insulating and encapsulating the sensors and circuits, various physiological parameters of the human body (temperature, ion concentration, pH, etc.) can be monitored in real time during clinical medical procedures. For example, during indwelling needle infusion, real-time temperature changes at the infusion point inside the blood vessel can be monitored simultaneously; during gastrointestinal endoscope treatment, the pressure of the catheter tip on soft tissues can be monitored simultaneously. These clinical applications have not yet achieved standardized manufacturing and integration on current medical device tubing. Even though there have been reports of similar catheter manufacturing methods (such as interventional catheters), which involve manufacturing circuits and sensors on a planar thin film and then winding the film onto the tubing, this method not only relies on an intermediate layer, which may be easily damaged during use, but is also only suitable for regular cylindrical tubing and cannot be widely adopted for other types of tubing. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 This is a flowchart illustrating the production process;

[0026] Figure 2 This is a picture of the actual film mask.

[0027] Figure 3 Nikon microscopy image of the surface of a medical tube after spin sputtering;

[0028] Figure 4 A Nikon microscope image showing the successful fabrication of a custom circuit on the surface of a medical tube after the flexible mask was peeled off.

[0029] Figure 5 This is a schematic diagram of a rotating clamp;

[0030] Figure 6 Figure 1 shows the data from a temperature sensing simulation experiment created on the indwelling needle tubing. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments. The following embodiments are only used to illustrate the performance of the present invention more clearly, and should not be limited to the embodiments described below.

[0032] Example 1:

[0033] A method for fabricating circuits and electrodes on a medical flexible tube

[0034] First, the silicon wafer surface was treated with an oxygen plasma cleaner at 20% power for 10 minutes and an oxygen input rate of 20 assm. Then, a Ni sacrificial layer was sputtered onto the silicon wafer surface using a sputtering instrument at DC sputtering power of 80W, an argon gas injection rate of 20 assm, a duty cycle of 70%, and for 15 minutes to obtain the Ni sacrificial layer.

[0035] P3000 photosensitive positive polyimide adhesive (Denni New Materials (Suzhou) Co., Ltd.) was removed from the freezer and brought to room temperature. It was then spin-coated onto a Ni sacrificial layer. The first stage spin-coating rate was 1000 rpm / min for 10 s; the second stage spin-coating rate was 3500 rpm / min for 20 s, followed by pre-baking at 120℃ for 3 min. After cooling, exposure was performed using a UV light source (Evata (Shanghai) Precision Optoelectronics Co., Ltd.) at 365 nm (exposure dose 400 mw / cm²). 2The exposure time was 20 seconds, and the mask was a custom-made film mask. After exposure, positive developer (DV-9000, Deni New Materials (Suzhou) Co., Ltd.) was used for immersion development for 60 seconds, followed by rinsing with deionized water to remove residual developer. The sample was placed on a constant temperature heating stage and post-baked in stages: 1) the temperature was increased from room temperature to 120 ℃ at a rate of 10 ℃ / min and held for 30 min; 2) the temperature was increased from 120 ℃ to 200 ℃ at a rate of 10 ℃ / min and held for 60 min; 3) the sample was removed after natural cooling to below 35 ℃.

[0036] The sample was placed in a Ni metal etching solution, and the Ni metal sacrificial layer was slowly etched until the film floated on the solution surface, completely releasing the photosensitive polyimide film mask. The film mask was then transferred to a container of deionized water using a silicon wafer to remove residual solution. The film mask was then transferred again to a container of 3 wt% polyvinyl alcohol solution using a silicon wafer. A medical tube was slowly immersed in the container, aligned with the film mask, and lifted and wound to ensure the film mask completely and shape-wise covers the medical tube.

[0037] The surface is then dried, and the product is placed in a 60°C vacuum oven for 5 minutes to remove any remaining solution.

[0038] The sample, except for the area covered by the thin-film mask, is completely covered with PI tape and then placed in a rotary fixture (this rotary fixture mainly consists of a planetary and axial lifting assembly, including a lifting motor that drives the entire assembly to move vertically up and down; and a planetary and axial motor that drives the crossbar and sample to rotate simultaneously via a gear transmission system. The crossbar is equipped with a quick-release nut for fixing or adjusting the workpiece position; the sample position on the crossbar is used to clamp the workpiece to be operated. The overall structure is kept stable by supports and is suitable for assembly, inspection, or processing applications requiring multi-angle, multi-position adjustments).

[0039] Magnetron sputtering of the Au target was performed using DC sputtering at a power of 40 W, an argon gas flow rate of 20 assim, a duty cycle of 70%, and a rotation speed of 20 rpm / min for 20 min. After sputtering, the sample was removed, and the thin film mask and PI tape were peeled off to obtain the custom Au circuit.

[0040] Example 2:

[0041] The fabrication of the circuitry on the surface of the flexible tube in the medical device is basically the same as in Example 1, wherein... Figure 2 This is a physical image of the film mask. This embodiment uses... Figure 2 The left image in the image.

[0042] The circuit manufactured according to the method of Example 1 extends from the top to the bottom. The square bottom end is the interface portion, allowing for the connection of an external FPCB flexible circuit board. The circular top portion is the electrode area, reserved for subsequent fabrication of the sensor portion. The specific resolution of the circuit is 20μm. The specific medical device tubing used here is the tubing portion of an indwelling needle. After the circuit is manufactured, the prepared temperature-sensitive ink (mainly composed of graphene + Pedot:Pss) is drop-coated onto the top of the circuit, then dried in an 80°C sterile oven for 1 hour, and finally insulated. The device is inserted into a simulated artificial silicone tube purchased online and tested on a constant temperature heating platform. The test data is attached. Figure 6 The data shows that this indwelling needle, which integrates circuitry and temperature sensing, can monitor minute changes within the human body temperature range in real time, with a sensitivity of 0.4158%℃ and a linearity of 0.996, making it almost perfectly linear.

[0043] Example 3

[0044] Medical device tubing comes in a wide variety of types, ranging from gastrointestinal endoscope tubes a few millimeters thick to vascular interventional catheters as thin as 100 micrometers. Therefore, we can choose the linewidth size according to the basic medical catheter we need to fabricate. Polyimide photoresist, after high-temperature baking, possesses excellent mechanical properties, but its resolution decreases compared to ordinary photoresist. Currently, the maximum resolution of polyimide photoresist is generally between 3-8 micrometers, but it is possible that this type of photoresist will break through to nanometer-level resolution in the future. The resolution of any custom circuit we can fabricate on medical catheters is entirely determined by the performance of the photoresist. Therefore, we have successfully fabricated a circuit with a resolution of approximately 3 micrometers on a vascular interventional catheter. The basic manufacturing method is essentially the same as in Example 1, only requiring changes to the linewidth of the photomask during photolithography.

[0045] The present invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.

Claims

1. A method of manufacturing custom circuits on medical tubing of all types, characterized by, It comprises the following steps: Step 1: clean the surface of the silicon wafer, prepare a layer of sacrificial layer on the surface of the silicon wafer, clean the silicon wafer by oxygen plasma machine, and prepare a layer of metal sacrificial layer or polymer sacrificial layer by vacuum evaporation, sputtering process, electroplating and chemical vapor deposition or water-soluble polymer spin coating method; Then spin-coat polyimide photoresist, and use ultraviolet lithography technology to pattern the photoresist to obtain a patterned photoresist film mask sample; Step 2: Put the sample obtained in step 1 into the sacrificial layer dissolving solution, and after the corresponding sacrificial layer is slowly etched and dissolved by the dissolving solution, the patterned photoresist film mask will float on the surface of the solution; Step 3: Use the transfer substrate to take out the patterned photoresist film mask, first transfer it to a container containing deionized water, then slowly dilute the residual solution on the surface of the film mask with deionized water, and then use the transfer substrate again to take out the patterned photoresist film mask, and finally transfer it to a container containing adhesive aqueous solution; Slowly put the medical hose into the solution, align the flexible photoresist film, and stick it up to wrap the flexible photoresist mask on the surface of the medical hose completely and conformally, and then put it into an oven for drying; Step 4: After masking the remaining part of the medical hose exposed to the outside with adhesive tape, put it into a coating chamber for rotary physical vapor deposition coating; After coating is completed, take it out of the chamber, peel off the adhesive tape cover and the flexible photoresist mask, and the complete custom circuit is successfully prepared on the medical hose.

2. The method of claim 1, wherein: The polyimide photoresist is P3000.

3. The method of claim 1, wherein: The ultraviolet lithography technology uses polyimide photoresist, which can be positive photoresist or negative photoresist; spin-coat at a speed of 1000 rpm / min for 10 s, then spin-coat at a speed of 3500 rpm / s for 20 s; then perform a series of steps of pre-baking, exposure, development and post-baking.

4. The method of claim 1, wherein the method is used to manufacture custom circuits on medical tubing of various types. The polyimide photoresist is P3000 series photosensitive positive polyimide material or P2000 series negative photosensitive polyimide material.

5. The method of claim 1, wherein the method is used to manufacture custom circuits on medical tubing of all types. The pre-baking parameters require constant heating at 120℃ for 3 minutes, the exposure uses a 365nm ultraviolet light source, and the post-baking requires slow heating until 200℃, constant heating for 60 minutes.

6. The method of claim 1, wherein: In step 2, the dissolving solution used needs to slowly dissolve the corresponding sacrificial layer until the flexible photoresist film floats on the surface of the solution.

7. The method of claim 1, wherein: In step 3, the transfer substrate needs to transfer the flexible photoresist film twice; the first transfer is to clean the residual solution on the surface of the flexible photoresist film, and the second transfer is to make the surface of the flexible photoresist film have a certain adhesion.

8. The method of claim 1, wherein: In step 3, the water transfer method is used to transfer the flexible photoresist film to the surface of the medical hose completely and conformally by water pressure.

9. The method of claim 1, wherein: In step 3, the medical hose is put into a sterile oven for drying, so that the flexible photoresist film and the medical hose are tightly bonded together.

10. The method of claim 1, wherein: In step 4, use the self-made rotary table clamp to put the medical hose into the clamp, which can rotate 360 degrees without dead angle coating.

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