Flexible organic electrochemical transistor sensor for electrocardiosignal detection

Abstract

The utility model relates to a flexible organic electrochemical transistor sensor for electrocardiosignal detection, and belongs to the technical field of flexible microelectronic devices. According to the utility model, the flexible substrate with excellent bending performance and the organic semiconductor channel material are adopted, the use comfort of a patient is greatly improved, the sensor is ensured to be tightly attached to the skin, meanwhile, the channel of the sensor adopts the interdigital electrode structural design, the ion-electronic signal transduction capability is realized, and the application range is wide. In-situ amplification can be carried out on detected electrocardiosignals, and the detection sensitivity and the detection stability are improved. The prepared flexible electrocardio sensor can be used for multi-scene and continuous'non-sensitive 'electrocardio signal detection, and has potential value in the fields of special group monitoring, wearable application research and the like.

Description

Technical Field

[0001] The utility model relates to a flexible organic electrochemical transistor sensor for electrocardiogram signal detection, belonging to the technical field of flexible microelectronic devices. Background Art

[0002] At present, ordinary commercial ECG monitors are usually bulky and have complex measurement circuits. They have certain restrictions on normal physiological activities of people and are not conducive to long-term continuous monitoring. ECG patches in contact with the human epidermis may have high sensitization. Cardiovascular diseases such as heart disease often have the characteristics of strong suddenness and a large patient population. Traditional ECG monitors are more suitable for measuring clinical ECG signals, and there are great limitations in measuring ECG signals of patients in other active states. Compared with traditional ECG monitors, flexible organic electrochemical transistor sensors can achieve high-sensitivity ECG signal detection, improve detection sensitivity and signal-to-noise ratio. In addition, the sensor has excellent bendability, which improves wearing comfort and ECG signal detection stability. When the sensor is flexibly integrated with the back-end signal conditioning and wireless transmission circuit, wireless and miniaturized detection is realized to ensure the normal physiological activities of the person being tested to the greatest extent. The flexible substrate has excellent biocompatibility and is used for daily ECG monitoring or scientific research. It can reduce the probability of allergic reactions during use, improve the credibility of detection, expand the user group range of ECG sensors, and improve the comfort of patients. Liao et al. prepared flexible organic electrochemical sensors for the detection of glucose, uric acid, etc., but did not involve the field of ECG signal detection. Campana et al. first used organic electrochemical transistors prepared on degradable flexible substrates for the detection of ECG signals, but the device size was large and the signal-to-noise ratio of the collected ECG signals was poor, resulting in less effective information. Therefore, improving the comfort and sensitivity of ECG monitoring is still an urgent problem to be solved. Using a simple and easy method to use flexible organic electrochemical transistor sensors for highly sensitive, "insensitive" ECG signal detection is a good and feasible solution. Summary of the invention

[0003] The technical problem to be solved by the utility model is: in view of the shortcomings of the above technologies, the utility model provides a flexible organic electrochemical transistor sensor for ECG signal detection. The utility model can obtain the current change in the conductive polymer layer through the current difference between the drain and the source, and provide data support for the instant detection of ECG signals. The utility model has high sensitivity in ECG signal detection, and improves detection sensitivity and signal-to-noise ratio. Moreover, the sensor has excellent bendability, which improves wearing comfort and ECG signal detection stability.

[0004] The technical scheme of the utility model is as follows: the utility model provides a flexible organic electrochemical transistor sensor for electrocardiogram signal detection, comprising a channel structure and a gate structure; the channel structure comprises a conductive polymer layer 2, a channel electrode 3, a first flexible substrate 4, a drain electrode 5, and a source electrode 6; the gate structure comprises a gate sensing region 7 and a gate electrode 8; a source electrode 6 and a drain electrode 5 are arranged on the first flexible substrate 4, a channel electrode 3 of an interdigitated electrode structure is formed between the source electrode 6 and the drain electrode 5, and the source electrode 6 and the drain electrode 5 are connected through the conductive polymer layer 2 above the channel electrode 3, and the device is packaged by a flexible packaging layer 1. During packaging, the source electrode 6, the drain electrode 5, and the upper surface of the conductive polymer layer 2 are leaked to form a channel structure of the sensor;

[0005] A gate sensing region 7 and a gate 8 are arranged on the second flexible substrate 9. A layer of Ag / AgCl and then a layer of organic semiconductor material are arranged on the surface of the gate sensing region 7. The packaging is completed using a flexible packaging layer 1. During packaging, the upper surfaces of the gate sensing region 7 and the gate 8 are exposed to form a gate structure of the sensor.

[0006] Furthermore, the first flexible substrate 4 and the second flexible substrate 9 used are one of polyester film, polyimide or polyparaxylene film, and the thickness of the film is 5-80 microns.

[0007] Furthermore, the channel electrode 3, the source electrode 6, and the drain electrode 5 are arranged on the first flexible substrate 4 by a metal deposition method, and the metal used is one or more of gold, platinum, copper, chromium, titanium, rhodium, and palladium; the metal deposition method used is one or more of radio frequency magnetron sputtering, thermal evaporation, pulsed laser deposition, and electron beam evaporation.

[0008] Furthermore, the thickness of the deposited metal film is 10-100 nanometers.

[0009] Furthermore, the formed sensor channel electrode 3 has a length of 1-6 micrometers, a width of 120-500 micrometers, a forked-finger electrode structure, and an area of ​​the sensor gate 8 is 9-36 square millimeters.

[0010] Furthermore, the organic semiconductor material is a polythiophene polymer, and the film thickness is 30-200 nanometers.

[0011] Furthermore, the organic semiconductor material coating method is one of spin coating, blade coating or inkjet printing.

[0012] Furthermore, the method of disposing Ag / AgCl and the organic semiconductor material is a doctor blade coating method or an electrolytic method.

[0013] Furthermore, the device is packaged using SU-8 or polyparaxylene.

[0014] The working principle of the utility model is:

[0015] ECG signals come from the muscle tissue of the heart, in which pacemaker cells can spontaneously induce calcium ion influx and further cause cell depolarization. ECG signals spread rapidly to the entire heart area, causing rhythmic expansion and contraction to form a cardiac cycle. The macroscopic ion flow during the cardiac cycle will cause slight changes in the skin potential. In order to achieve ECG monitoring, the channel structure of the organic electrochemical transistor sensor is attached to the forearm, the gate structure is attached to the chest, a 0.3V safety gate voltage is applied to the gate 8 to achieve its maximum transconductance, and a voltage of 0.05V is applied to the channel electrode 3 of the device through the drain 5. When the gate voltage on the gate 8 changes potential due to heart beating, it will cause the current value in the conductive polymer layer 2 to change. The current change in the conductive polymer layer 2 is obtained by measuring the current difference between the drain 5 and the source 6, and the current signal is passed through an external matching preamplifier to convert the transient current into a readable voltage signal. After appropriate signal processing and data analysis, the measurement and visualization of the ECG signal is achieved.

[0016] The beneficial effects of the utility model are: the utility model can obtain the current change in the conductive polymer layer through the current difference between the drain and the source, providing data support for the instant detection of the ECG signal, the utility model has high sensitivity in ECG signal detection, and improves the detection sensitivity and signal-to-noise ratio. Moreover, the sensor has excellent bendability, which improves the wearing comfort and ECG signal detection stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A three-dimensional exploded view of the channel structure used in the flexible organic electrochemical transistor electrocardiograph sensor prepared by the utility model;

[0018] Figure 2 A top view of the channel structure used in the flexible organic electrochemical transistor electrocardiograph sensor prepared by the utility model;

[0019] Figure 3 A three-dimensional exploded view of the gate structure used in the flexible organic electrochemical transistor electrocardiograph sensor prepared by the utility model;

[0020] Figure 4 This is a top view of the gate structure used in the flexible organic electrochemical transistor electrocardiograph sensor prepared by the utility model.

[0021] Figure 1-Figure 4 The numbers in the figure are: 1-flexible encapsulation layer, 2-conductive polymer layer, 3-channel electrode, 4-first flexible substrate, 5-drain, 6-source, 7-gate sensing area, 8-gate, 9-second flexible substrate. DETAILED DESCRIPTION

[0022] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments.

[0023] Example 1: Figure 1-Figure 4 As shown, the utility model provides a flexible organic electrochemical transistor sensor for electrocardiogram signal detection, including a channel structure and a gate structure; the channel structure includes a conductive polymer layer 2, a channel electrode 3, a first flexible substrate 4, a drain electrode 5, and a source electrode 6; the gate structure includes a gate sensing area 7 and a gate electrode 8; a source electrode 6 and a drain electrode 5 are arranged on the first flexible substrate 4, a channel electrode 3 of an interdigitated electrode structure is formed between the source electrode 6 and the drain electrode 5, and the source electrode 6 and the drain electrode 5 are connected through the conductive polymer layer 2 above the channel electrode 3, and the device is packaged using a flexible packaging layer 1. During packaging, the source electrode 6, the drain electrode 5, and the upper surface of the conductive polymer layer 2 are leaked to form a channel structure of the sensor;

[0024] A gate sensing region 7 and a gate 8 are arranged on the second flexible substrate 9. A layer of Ag / AgCl and then a layer of organic semiconductor material are arranged on the surface of the gate sensing region 7. The packaging is completed using a flexible packaging layer 1. During packaging, the upper surfaces of the gate sensing region 7 and the gate 8 are exposed to form a gate structure of the sensor.

[0025] Furthermore, the first flexible substrate 4 and the second flexible substrate 9 used are one of polyester film, polyimide or polyparaxylene film, and the thickness of the film is 5-80 microns.

[0026] Furthermore, the channel electrode 3, the source electrode 6, and the drain electrode 5 are arranged on the first flexible substrate 4 by a metal deposition method, and the metal used is one or more of gold, platinum, copper, chromium, titanium, rhodium, and palladium; the metal deposition method used is one or more of radio frequency magnetron sputtering, thermal evaporation, pulsed laser deposition, and electron beam evaporation.

[0027] Furthermore, the thickness of the deposited metal film is 10-100 nanometers.

[0028] Furthermore, the formed sensor channel electrode 3 has a length of 1-6 micrometers, a width of 120-500 micrometers, a forked-finger electrode structure, and an area of ​​the sensor gate 8 is 9-36 square millimeters.

[0029] Furthermore, the organic semiconductor material is a polythiophene polymer, and the film thickness is 30-200 nanometers.

[0030] Furthermore, the organic semiconductor material coating method is one of spin coating, blade coating or inkjet printing.

[0031] Furthermore, the method of disposing Ag / AgCl and the organic semiconductor material is a doctor blade coating method or an electrolytic method.

[0032] Furthermore, the device is packaged using SU-8 or polyparaxylene.

[0033] The method for preparing the flexible organic electrochemical transistor sensor for electrocardiogram signal detection of the utility model specifically comprises the following steps:

[0034] Step 1: depositing a first flexible substrate 4 and a second flexible substrate 9 on a glass substrate respectively; the first flexible substrate 4 and the second flexible substrate 9 are one of polyester film, polyimide or polyparaxylene film, and the film thickness is 5-80 microns.

[0035] Step 2, depositing a metal film on the first flexible substrate 4, and preparing a channel electrode 3, a drain electrode 5 and a source electrode 6 by a photolithography process; the metal used in the step 2 is one or more of gold, platinum, copper, chromium, titanium, rhodium, and palladium; the metal deposition method used is one or more of radio frequency magnetron sputtering, thermal evaporation, pulsed laser deposition, and electron beam evaporation.

[0036] The thickness of the metal film deposited in step 2 is 10 nanometers.

[0037] The sensor channel electrode 3 formed in step 2 has a length of 1 micron, a width of 120 microns, and a forked electrode structure. The gate 8 of the sensor in step 2 has an area of ​​9 square millimeters.

[0038] The organic semiconductor material coating method used in step 2 is one of spin coating, blade coating or inkjet printing.

[0039] Step 3, preparing the gate sensing region 7 and the gate 8 on the second flexible substrate 9 by using the same process as step 2;

[0040] Step 4: coating an organic semiconductor material on the channel electrode 3 to form a conductive polymer layer 2; the organic semiconductor material used in step 4 is one of polythiophene polymers, and the film thickness is 30 nanometers.

[0041] Step 5: first coat a layer of Ag / AgCl and then coat a layer of organic semiconductor material on the surface of the gate sensing area 7; in step 5, the method of coating Ag / AgCl and the organic semiconductor material is a scraping method or an electrolysis method.

[0042] Step 6: encapsulate the device using a flexible encapsulation layer 1 of a flexible material, exposing only the upper surface area of ​​the conductive polymer layer 2, the drain 5, the source 6, the gate sensing area 7, and the gate 8, to obtain a sensor channel structure and a gate structure. In step 6, SU-8 or polyparaxylene is used to encapsulate the device.

[0043] Example 2: Figure 1-Figure 4 As shown, the utility model provides a flexible organic electrochemical transistor sensor for electrocardiogram signal detection. This embodiment is the same as embodiment 1, except that:

[0044] In the step 1, the first flexible substrate 4 and the second flexible substrate 9 used in the step 1 are one of polyester film, polyimide or polyparaxylene film, and the film thickness is 80 microns;

[0045] In step 2, the thickness of the deposited metal film is 100 nanometers. The length of the sensor channel electrode 3 formed in step 2 is 6 micrometers, the width of the channel electrode 3 is 500 micrometers, and the area of ​​the gate 8 of the sensor in step 2 is 36 square millimeters.

[0046] Furthermore, the organic semiconductor material used in step 4 is one of polythiophene polymers, and the film thickness is 200 nanometers.

[0047] Example 3: Figure 1-Figure 4 As shown, the utility model provides a flexible organic electrochemical transistor sensor for electrocardiogram signal detection. This embodiment is the same as embodiment 1, except that:

[0048] In the step 1, the first flexible substrate 4 and the second flexible substrate 9 used in the step 1 are one of polyester film, polyimide or polyparaxylene film, and the film thickness is 60 microns;

[0049] In step 2, the thickness of the deposited metal film is 70 nanometers. The length of the sensor channel electrode 3 formed in step 2 is 3 micrometers, the width of the channel electrode 3 is 300 micrometers, and the area of ​​the gate 8 of the sensor in step 2 is 20 square millimeters.

[0050] Furthermore, the organic semiconductor material used in step 4 is one of polythiophene polymers, and the film thickness is 110 nanometers.

[0051] Example 4: Figure 1-Figure 4As shown, the utility model provides a flexible organic electrochemical transistor sensor for electrocardiogram signal detection, including a channel structure and a gate structure; the channel structure includes a conductive polymer layer 2, a channel electrode 3, a first flexible substrate 4, a drain electrode 5, and a source electrode 6; the gate structure includes a gate sensing area 7 and a gate electrode 8; a source electrode 6 and a drain electrode 5 are arranged on the first flexible substrate 4, a channel electrode 3 of an interdigitated electrode structure is formed between the source electrode 6 and the drain electrode 5, and the source electrode 6 and the drain electrode 5 are connected through the conductive polymer layer 2 above the channel electrode 3, and the device is packaged using a flexible packaging layer 1. During packaging, the source electrode 6, the drain electrode 5, and the upper surface of the conductive polymer layer 2 are leaked to form a channel structure of the sensor;

[0052] A gate sensing region 7 and a gate 8 are arranged on the second flexible substrate 9. A layer of Ag / AgCl and then a layer of organic semiconductor material are arranged on the surface of the gate sensing region 7. The packaging is completed using a flexible packaging layer 1. During packaging, the upper surfaces of the gate sensing region 7 and the gate 8 are exposed to form a gate structure of the sensor.

[0053] The utility model discloses a method for preparing a flexible organic electrochemical transistor sensor for electrocardiogram signal detection, the method comprising the following steps:

[0054] Step 1: First, a glass support substrate for polyparaxylene film deposition is ultrasonically cleaned with acetone, deionized water, and isopropanol for 15 minutes each, and then dried with nitrogen. Then, a polyparaxylene film with a thickness of 8 microns is deposited on the glass surface using a dedicated chemical vapor deposition device to obtain a first flexible substrate 4 and a second flexible substrate 9;

[0055] Step 2, spin-coat the surface of the first flexible substrate 4 with photoresist (AZ9260, 4000rpm), heat at 110 degrees Celsius for 3 minutes to fully volatilize the photoresist solvent, spin-coat the surface of the film with photoresist (AZ9260, 4000rpm), heat at 110 degrees Celsius for 3 minutes to fully volatilize the photoresist solvent, use a photolithography machine to expose the photoresist through a mask, and then use a developer to develop the exposed photoresist and obtain a pattern, which is the pattern of the channel electrode 3, drain electrode 5, and source electrode 6 of the overlay interdigitated electrode structure. Use a magnetron sputtering method to first plate Cr with a thickness of 10 nanometers, plate a layer of 70 nanometers of gold (Au) on the Cr, and finally soak the substrate treated in the above steps with acetone, and the Cr film and Au film in places other than the channel electrode 3, drain electrode 5, and source electrode 6 patterns will be washed off, leaving only the patterned parts, and obtaining the channel electrode 3, drain electrode, and source electrode 6;

[0056] Step 3: Prepare the gate sensing region 7 and the gate 8 on the second flexible substrate 9 by the same steps as step 2;

[0057] Step 4: Clean the channel electrode 3 deposited on the first flexible substrate 4 with an oxygen plasma cleaner for 5 minutes, pattern it by photolithography, and then spin-coat a uniform layer of polyethylene dioxythiophene (PEDOT:PSS) solution, and control the thickness of the film to 50 nanometers by controlling the spin coating speed; after the solution on the surface of the channel electrode 3 is slightly dry, transfer it to a glove box (filled with high-purity nitrogen), anneal it at 120 degrees Celsius for 30 minutes, and take it out of the glove box after it is naturally cooled to room temperature, and peel the PEDOT:PSS from the substrate by immersion in acetone and strong shaking, so as to coat the PEDOT:PSS on the channel electrode 3 to form a conductive polymer layer 2;

[0058] Step 5: Scrape a layer of Ag / AgCl slurry on the surface of the gate sensing area 7 and then scrape a layer of PEDOT:PSS.

[0059] Step 6: encapsulate the device with SU-8 2002 photoresist, and use photolithography to expose only the polymer conductive layer 3, the drain 5, the source 6, the gate sensing area 7 and the upper surface of the gate 8; immerse the prepared channel structure and the gate structure in water, slowly peel off the entire sensor from the edge from the glass support substrate, blow dry with nitrogen, and obtain a flexible organic electrochemical transistor sensor for electrocardiogram signal detection.

[0060] The working principle of the utility model is:

[0061] ECG signals come from the muscle tissue of the heart, in which pacemaker cells can spontaneously induce calcium ion influx and further cause cell depolarization. ECG signals spread rapidly to the entire heart area, causing rhythmic expansion and contraction to form a cardiac cycle. The macroscopic ion flow during the cardiac cycle will cause slight changes in the skin potential. In order to achieve ECG monitoring, the channel structure of the organic electrochemical transistor sensor is attached to the forearm, the gate structure is attached to the chest, a 0.3V safety gate voltage is applied to the gate 8 to achieve its maximum transconductance, and a voltage of 0.05V is applied to the channel electrode 3 of the device through the drain 5. When the gate voltage on the gate 8 changes potential due to heart beating, it will cause the current value in the conductive polymer layer 2 to change. The current change in the conductive polymer layer 2 is obtained by measuring the current difference between the drain 5 and the source 6, and the current signal is passed through an external matching preamplifier to convert the transient current into a readable voltage signal. After appropriate signal processing and data analysis, the measurement and visualization of the ECG signal is achieved.

[0062] The specific embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A flexible organic electrochemical transistor sensor for electrocardiogram signal detection, characterized in that: The invention comprises a channel structure and a gate structure; the channel structure comprises a conductive polymer layer (2), a channel electrode (3), a first flexible substrate (4), a drain electrode (5), and a source electrode (6); the gate structure comprises a gate sensing region (7) and a gate electrode (8); a source electrode (6) and a drain electrode (5) are arranged on the first flexible substrate (4); a channel electrode (3) with an interdigitated electrode structure is formed between the source electrode (6) and the drain electrode (5); the source electrode (6) and the drain electrode (5) are connected via the conductive polymer layer (2) above the channel electrode (3); the device is packaged using a flexible packaging layer (1); during packaging, the source electrode (6), the drain electrode (5), and the upper surface of the conductive polymer layer (2) are exposed to form a channel structure of the sensor; A gate sensing region (7) and a gate (8) are arranged on a second flexible substrate (9); a layer of Ag / AgCl and then a layer of organic semiconductor material are arranged on the surface of the gate sensing region (7); and packaging is completed using a flexible packaging layer (1); during packaging, the upper surfaces of the gate sensing region (7) and the gate (8) are exposed to form a gate structure of the sensor.

2. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 1, characterized in that: The first flexible substrate (4) and the second flexible substrate (9) used are one of polyester film, polyimide or polyparaxylene film, and the film thickness is 5-80 microns.

3. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 1, characterized in that: The channel electrode (3), source electrode (6) and drain electrode (5) are arranged on the first flexible substrate (4) by a metal deposition method, and the metal used is one or more of gold, platinum, copper, chromium, titanium, rhodium and palladium; the metal deposition method used is one or more of radio frequency magnetron sputtering, thermal evaporation, pulsed laser deposition and electron beam evaporation.

4. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 3, characterized in that: The thickness of the deposited metal film is 10-100 nanometers.

5. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 1, characterized in that: The formed sensor channel electrode (3) has a length of 1-6 microns, a width of 120-500 microns, a forked electrode structure, and an area of ​​the sensor grid (8) of 9-36 square millimeters.

6. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 2, characterized in that: The organic semiconductor material is a polythiophene polymer, and the film thickness is 30-200 nanometers.

7. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 2, characterized in that: The organic semiconductor material coating method is one of spin coating, blade coating or inkjet printing.

8. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 2, characterized in that: The method of disposing Ag / AgCl and the organic semiconductor material is a doctor blade method or an electrolytic method.

9. The flexible organic electrochemical transistor sensor for electrocardiographic signal detection according to claim 2, characterized in that: The device is packaged using SU-8 or polyparaxylene.

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