阅读说明：本技术 一种超高增益有机放大器及其制备方法 (Ultrahigh-gain organic amplifier and preparation method thereof ) 是由 王欣然 罗中中 施毅 于 2020-12-03 设计创作，主要内容包括：本发明公开一种超高增益有机放大器及其制备方法。该超高增益有机放大器由一个驱动晶体管和一个负载晶体管串联构成,其中负载晶体管的栅极与源极短接；驱动晶体管和负载晶体管的栅极介电层为铁电性氧化物薄膜,半导体沟道层为有机分子薄膜。其制备方法包括：在衬底上制备局域栅极金属层；在局域栅极金属层表面生长铁电性氧化物薄膜作为介电层；制备半导体层和电极层。该超高增益有机放大器可以在3V工作电压下实现超过10000的电压增益,1V工作电压下实现4000的增益,同时,可以实现电池供电。该超高增益的有机放大器亦可在柔性衬底上实现。另外,该有机放大器可用于各类微小信号的检测和放大。(The invention discloses an ultrahigh gain organic amplifier and a preparation method thereof. The ultrahigh gain organic amplifier is formed by connecting a driving transistor and a load transistor in series, wherein the grid electrode of the load transistor is in short circuit with the source electrode; the grid dielectric layers of the driving transistor and the load transistor are ferroelectric oxide films, and the semiconductor channel layer is an organic molecular film. The preparation method comprises the following steps: preparing a local grid metal layer on a substrate; growing a ferroelectric oxide film on the surface of the local gate metal layer as a dielectric layer; and preparing a semiconductor layer and an electrode layer. The ultrahigh-gain organic amplifier can realize the voltage gain over 10000 under the working voltage of 3V, realize the gain of 4000 under the working voltage of 1V and realize the power supply of a battery. The ultra-high gain organic amplifier can also be implemented on a flexible substrate. In addition, the organic amplifier can be used for detecting and amplifying various tiny signals.)

1. An ultrahigh gain organic amplifier is characterized in that the ultrahigh gain organic amplifier is formed by connecting a driving transistor and a load transistor in series, wherein the grid electrode of the load transistor is in short circuit with the source electrode; the grid dielectric layers of the driving transistor and the load transistor are ferroelectric oxide films, and the semiconductor channel layer is an organic molecular film.

2. The ultra-high gain organic amplifier according to claim 1, wherein the ferroelectric oxide thin film is one of a hafnium-based ferroelectric oxide thin film and a perovskite-structured ferroelectric oxide thin film.

3. The ultra-high gain organic amplifier according to claim 1, wherein the organic molecular thin film is one of an organic small molecule semiconductor thin film and an organic polymer semiconductor thin film.

4. A method for manufacturing the ultra-high gain organic amplifier of claim 1, comprising the steps of:

(1) preparing a local grid metal layer on a substrate according to the structure of the organic amplifier;

(2) growing a ferroelectric oxide film on the surface of the local gate metal layer as a dielectric layer;

(3) growing a single-layer organic molecular film on the surface of the dielectric layer to serve as a semiconductor channel layer;

(4) and preparing an electrode layer on the surface of the semiconductor channel layer.

5. The method for preparing an ultra-high gain organic amplifier according to claim 4, wherein in the step (1), the substrate is a rigid substrate or a flexible substrate.

6. The method of claim 4, wherein the dielectric layer further comprises a non-ferroelectric oxide film grown on the surface of the ferroelectric oxide film for capacitance matching.

7. The method of claim 6, wherein the non-ferroelectric oxide film is one of alumina, zirconia, silica, hafnia, and titania.

Technical Field

The invention relates to an amplifier and a preparation method thereof, in particular to an ultrahigh-gain organic amplifier and a preparation method thereof, belonging to the technical field of organic semiconductor electronic devices and wearable electronic devices.

Background

Due to low processing cost and intrinsic flexibility, organic semiconductor devices have been widely used in wearable electronic applications, such as internet of things, radio frequency electronic tags, wearable sensors, and the like. Organic semiconductors have been studied for these applications, but the circuits used generally require a large operating voltage, resulting in high power consumption and unsuitable battery-powered operation.

At the same time, the most challenging part of a wearable electronic device is the sensor interface, which, as an analog circuit application, requires a low voltage, low power circuit with high gain, high input impedance and a simple, low cost manufacturing process. At present, a signal amplification module used in wearable electronic equipment partially adopts a traditional amplification chip, but the traditional amplification chip is difficult to realize complete flexibility; there are also some flexible amplifiers with new structure, but the gain is about 100 at most.

Based on this, the inventor designs and develops an ultrahigh gain organic amplifier with a gain exceeding 10⁴And complete flexibility can be achieved.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems of the existing organic amplifier, the invention provides a method for realizing the voltage gain exceeding 10 under the low working voltage⁴And provides a method for preparing the organic amplifier.

The technical scheme is as follows: the invention relates to an ultrahigh-gain organic amplifier, which is formed by connecting a driving transistor and a load transistor in series, wherein the grid electrode of the load transistor is in short circuit with the source electrode; in the amplifiers of the driving transistor and the load transistor, a grid dielectric layer is a ferroelectric oxide film, and a semiconductor channel layer is an organic molecular film. The negative capacitance effect introduced by using the ferroelectric oxide film as the dielectric layer breaks the Boltzmann limit of the organic thin film transistor for the first time, greatly improves the transconductance and the output resistance of the thin film transistor in the amplifier, and enables the amplifier to realize ultra-low working voltage and ultra-high voltage gain.

Preferably, the ferroelectric oxide thin film is one of a hafnium-based ferroelectric oxide thin film and a perovskite-structured ferroelectric oxide thin film. Further preferably, the hafnium-based ferroelectric oxide is hafnium zirconium oxygen, hafnium aluminum oxygen, hafnium lanthanum oxygen, hafnium silicon oxygen, hafnium yttrium oxygen, hafnium strontium oxygen, hafnium gadolinium oxygen, hafnium neodymium oxygen, or hafnium samarium oxygen; the perovskite structure ferroelectric oxide is lead zirconate titanate, lead lanthanum zirconate titanate, strontium barium titanate or strontium bismuth tantalate. Any organic semiconductor film can be used as the organic molecular film, and the organic semiconductor material is preferably an organic small molecular semiconductor or an organic polymer semiconductor, and more preferably 2, 7-dioctyl [1] benzothieno [3,2-b ] benzothiophene, 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene, pentacene, or the like.

The invention relates to a preparation method of an ultrahigh gain organic amplifier, which comprises the following steps:

(1) preparing a local grid metal layer on a substrate according to the structure of the organic amplifier;

(2) growing a ferroelectric oxide film on the surface of the local gate metal layer as a dielectric layer;

(3) growing a single-layer organic molecular film on the surface of the dielectric layer to serve as a semiconductor channel layer;

(4) and preparing an electrode layer on the surface of the semiconductor channel layer.

In the step (1), the substrate may be a rigid substrate or a flexible substrate, and when a flexible substrate is used, a flexible organic amplifier with ultrahigh gain can be obtained, so that the substrate can be applied to a wearable electronic device. The local gate metal layer can be selected from various metals according to requirements, and is preferably a titanium/gold double-layer metal.

In the step (2), preferably, an atomic layer deposition technique is used to grow a ferroelectric oxide film on the surface of the local gate metal layer, and the specific method is as follows: and placing the substrate with the prepared local gate metal layer in an atomic layer deposition cavity, vacuumizing, raising the temperature of the cavity, introducing a metal source and an oxidation source, and depositing in situ on the surface of the substrate to obtain the uniform ferroelectric oxide film. The growth temperature is adjusted according to the properties of the ferroelectric oxide, and when hafnium zirconium oxygen is used, the growth temperature is preferably about 150 ℃. Preferably, the dielectric layer further comprises an ultra-thin non-ferroelectric oxide film, and in the step (1), after the ferroelectric oxide film is grown, a layer of non-ferroelectric oxide film can be continuously grown on the surface of the ferroelectric oxide film for isolation protection and capacitance matching; preferably, the non-ferroelectric oxide thin film is preferably aluminum oxide, zirconium oxide, silicon oxide, hafnium oxide, titanium oxide, or the like, and the thickness thereof is preferably 0 to 6 nm.

In the step (3), the semiconductor channel layer may be made of any organic semiconductor material, preferably organic small molecule semiconductor material or organic polymer semiconductor material, such as pentacene, 2, 7-dioctyl [1] benzothieno [3,2-b ] benzothiophene, and 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene. The preparation method of the semiconductor channel layer comprises thermal evaporation, vapor phase epitaxial deposition, a solution method and the like. As a preferred example, the semiconductor channel layer is prepared by a solution half-moon shearing method, and the preparation process specifically comprises the following steps: organic semiconductor material (such as 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene) is prepared into growth solution, then the growth solution is injected into the intersection of the dielectric layer and the scraper, and the scraper is controlled to continuously move towards one direction, so that the growth of organic molecules is completed. When 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene is used as the organic molecule, the solvent used for the growth solution may be tetralin, which dissolves 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene. After the growth solution is prepared, the growth solution is preferably placed in a water bath for continuous heating, so that the organic molecules in the solution are fully dissolved, and nucleation points on the organic film are reduced.

In the step (3), the electrode layer may be made of a plurality of metals, such as gold, platinum, silver, titanium/gold, and the like, and the preparation method includes thermal evaporation, electron beam evaporation, van der waals transfer method, and the like. As a preferable example, the electrode layer is made of gold by van der waals transfer method.

The ultrahigh gain organic amplifier can be used for detecting and amplifying various tiny signals, such as electrocardio, pulse and the like of a human body. Specifically, after the ultrahigh-gain organic amplifier is prepared, a tiny signal is introduced into an input end of the organic amplifier, and an amplified signal is collected at an output end by using voltage testing equipment.

The invention principle is as follows: the ultra-high gain organic amplifier of the invention adopts ferroelectric oxide as the dielectric layer of the organic thin film transistor, the introduced negative capacitance effect breaks the Boltzmann limit of the traditional organic thin film transistor, effectively improves the transconductance and the output resistance of the thin film transistor in the amplifier, and combines with the organic molecular thin film semiconductor layer to realize the ultra-low working voltage and the ultra-high voltage gain of the organic amplifier. According to Landau-Devonshire theory, the Gibbs free energy density (U) of a single domain ferroelectric material is given by: u ═ α P2+ β P4+ γ P6-E · P, where P is polarization and E is the electric field; by making dU/dP 0, a continuous P-E curve can be obtained: e2 α P +4 β P³+6γP⁵Including all possible polarization states of the ferroelectric material in response to an external electric field; in this P-E curve, a portion exhibits a negative P-E slope, which physically represents a negative capacitance region, i.e., indicates that the ferroelectric material can introduce a negative capacitance effect. The existing hafnium-based ferroelectric oxide and perovskite-structured ferroelectric oxide both have ferroelectric properties, so that the hafnium-based ferroelectric oxide and the perovskite-structured ferroelectric oxide can be used as dielectric layer materials of transistors to introduce a negative capacitance effect, and can be used in the ultrahigh-gain organic amplifier to realize ultralow working voltage and ultrahigh voltage gain of the organic amplifier.

Has the advantages that: compared with the prior art, the invention has the advantages that: (1) the ultrahigh gain organic amplifier can realize more than 10 under low working voltage⁴The maximum voltage gain can reach 1.1 multiplied by 10⁴The record of the same kind structure is far higher than the reported results of the same kind structure of organic semiconductor, two-dimensional material, carbon nanotube, oxide semiconductor, etc.; and workThe voltage is as low as 1V, and the battery can be powered; (2) the performance of the low voltage and the ultrahigh gain ensures that the organic amplifier can realize the detection and the method of the tiny signal under the ultralow working voltage, and lays a foundation for the application of an organic semiconductor device in the field of low-power consumption electronics; (3) the preparation process of the organic amplifier is compatible with the flexible substrate, so that the flexible organic amplifier can be realized, and a foundation is laid for the application of an organic semiconductor device in the field of wearable medical electronics; (4) the organic amplifier has the advantages of simple structure, easy preparation, potential of being expanded into a complex circuit and wide application prospect.

Drawings

FIG. 1 is a circuit diagram (a) and a device cross-sectional schematic (b) of an ultra-high gain organic amplifier prepared in example 1;

FIG. 2 is a photomicrograph of an ultra-high gain organic amplifier prepared in example 1;

fig. 3 is an electrical characteristic curve of the ultra-high gain organic amplifier prepared in example 1, in which (a) is a voltage transfer characteristic curve and (b) is a gain curve obtained from the voltage transfer characteristic curve;

fig. 4 is an electrical characteristic curve of the flexible ultra-high gain organic amplifier prepared in example 2, in which a solid line is a voltage transfer characteristic curve and a dotted line is a gain curve according to the voltage transfer characteristic curve;

FIG. 5 is a photograph of a battery powered amplifier module prepared in example 3, wherein (a) is a photograph of the amplifier module and (b) is an electrical characteristic curve of the amplifier module;

FIG. 6 is a schematic diagram of the application of the ultrahigh gain organic amplifier to human body ECG detection and amplification in example 4, in which (a) is an ECG test and (b) is a collected human body ECG;

FIG. 7 is an electrocardiogram of the cardiac electric signal detection performed on patients with atrial fibrillation in example 5; wherein, (a) is the electrocardiogram of the patient collected by clinical equipment, and (b) is the electrocardiogram of the patient collected by an ultrahigh gain organic amplifier.

Detailed Description

The technical solution of the present invention is further explained with reference to the drawings and the embodiments.

The invention relates to an ultrahigh gain organic amplifier, which is a depletion type-load amplifier formed by connecting a driving transistor and a load transistor in series, wherein the grid electrode of the load transistor is in short circuit with the source electrode, and the circuit structure is shown as a figure 1 (a); the amplifier of the driving transistor and the load transistor has gate dielectric layer of ferroelectric oxide film and semiconductor channel layer of organic molecular film, and has dielectric layer of ferroelectric oxide as organic film transistor combined with the semiconductor layer of organic molecular film to reach 1.1 × 10⁴The voltage gain of (2), which is the highest record of the devices with the same structure at present; meanwhile, the amplifier can work under the ultra-low working voltage (1V) and can be driven by a battery. In addition, the ultra-high gain organic amplifier may be implemented on a flexible substrate.

Example 1

The preparation method of the ultrahigh gain organic amplifier comprises the following steps:

1) local gate electrodes are designed and fabricated. In this example, a depletion-mode load amplifier in which two organic thin film transistors are connected in series is designed, and fig. 1(a) is a circuit diagram of the amplifier and fig. 1(b) is a cross-sectional view of the designed amplifier. Local gate electrodes were prepared using a standard electron beam exposure and evaporation process with commercially available silicon dioxide/silicon as the substrate, according to the amplifier circuit diagram, with gate metals of 10nm titanium and 10nm gold.

2) And growing hafnium zirconium oxygen/aluminum oxide on the substrate with the local gate electrode as a dielectric layer by utilizing an atomic layer deposition technology. Putting the substrate into an atomic layer deposition cavity, vacuumizing the cavity, heating to 150 ℃, keeping for 30min, and taking tetrakis (dimethylamino) hafnium and tetrakis (dimethylamino) zirconium as metal sources and water as an oxidation source. The procedure for growing hafnium zirconium oxygen once is to first pulse a zirconium source, then a water source, then a hafnium source, and finally a water source, which is a growth cycle. Setting 100 cycles, starting to grow the hafnium zirconium oxygen film with the thickness of about 22 nm. After the hafnium zirconium oxygen growth is finished, trimethyl aluminum is used as a metal source, water is used as an oxidation source, the cycle number is set to be 20, and the aluminum oxide starts to grow and has the thickness of about 2 nm. After the growth is finished, the substrate is placed into a rapid annealing furnace and is rapidly annealed for 1min at the temperature of 450 ℃.

3) And etching the hafnium zirconium oxide on part of the gate metal layer by using the inductively coupled plasma for gate-source through hole connection and later-stage test connection. Firstly, a sample is exposed by using an electron beam to expose a region to be etched, and other regions are protected by photoresist. Then, the sample is put into the mixed gas of boron trichloride and chlorine, wherein the flow rate of boron trichloride is 25sccm, and the flow rate of chlorine is 10 sccm. The bias power is set to 20W, the RF power is set to 280W, and the etching time is set to 30 s.

4) 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene film grows by a solution half-moon shearing method, and then a device electrode is transferred by a van der Waals transfer method. Firstly, preparing an organic solution with the concentration of 0.2mg/mL by using a solvent of tetralin and organic molecule powder 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene; then, injecting the solution into the intersection of the substrate and the scraper; the temperature of the substrate and the scraper is set to be 65 ℃, the distance is 100 mu m, the inclination angle of the scraper is 15 ℃, the speed is 2-3 mu m/s, and the scraper is controlled by an electric displacement table to continuously move towards one direction to finish the growth of organic crystals; then spin-coating 1-2 μm polymethyl methacrylate on the patterned device electrode, and baking for 5min at 150 ℃; and then the polymer and the gold electrode are lifted together by utilizing the heat release adhesive tape and transferred to the surface of the organic semiconductor channel layer. Fig. 2 is an optical micrograph of a prepared ultra-high gain organic amplifier with drive and load transistors having aspect ratios of 15 and 40, respectively.

And carrying out electrical test on the prepared ultrahigh-gain organic amplifier. FIG. 3(a) is a graph showing the voltage transfer characteristics of the organic amplifier, with operating voltages of-1V and-3V, respectively, and the device completed voltage switching in the range of a few millivolts. Fig. 3(b) shows the dependence of the gain of the amplifier on the input voltage calculated from the voltage transfer characteristic curve of the organic amplifier, and it can be seen that the maximum gain value of the amplifier is 11220, which is far greater than all reported amplifier performances.

Example 2

Preparing an ultrahigh gain organic amplifier on a flexible substrate, comprising the following steps:

1) a polyimide film is prepared on a silicon substrate as a flexible substrate. First, a polyimide solution (AA-49, KANEKA) was spin coated on a silica/silicon substrate at 1500 rpm for 45 s. Then, the mixture was baked at 350 ℃ for 1 hour. The preparation process is completed in a glove box with nitrogen atmosphere.

2) Local gate electrodes are designed and fabricated. Local gate electrodes were prepared using standard electron beam exposure and evaporation processes, with gate metals of 10nm titanium and 10nm gold, according to the amplifier circuit diagram designed in figure 1 (a).

3) And growing hafnium zirconium oxygen/aluminum oxide on the substrate with the local gate electrode as a dielectric layer by utilizing an atomic layer deposition technology. Putting the substrate into an atomic layer deposition cavity, vacuumizing the cavity, heating to 150 ℃, keeping for 30min, and taking tetrakis (dimethylamino) hafnium and tetrakis (dimethylamino) zirconium as metal sources and water as an oxidation source. The procedure for growing hafnium zirconium oxygen once is to first pulse a zirconium source, then a water source, then a hafnium source, and finally a water source, which is a growth cycle. Setting 100 cycles, starting to grow the hafnium zirconium oxygen film with the thickness of about 22 nm. After the hafnium zirconium oxygen growth is finished, trimethyl aluminum is used as a metal source, water is used as an oxidation source, the cycle number is set to be 20, and the aluminum oxide starts to grow and has the thickness of about 2 nm. After the growth is finished, the substrate is placed into a rapid annealing furnace and rapidly annealed for 1min at the temperature of 350 ℃.

4) And etching the hafnium zirconium oxide on part of the gate metal layer by using the inductively coupled plasma for gate-source through hole connection and later-stage test connection. Firstly, a sample is exposed by using an electron beam to expose a region to be etched, and other regions are protected by photoresist. Then, the sample is put into the mixed gas of boron trichloride and chlorine, wherein the flow rate of boron trichloride is 25sccm, and the flow rate of chlorine is 10 sccm. The bias power is set to 20W, the RF power is set to 280W, and the etching time is set to 30 s.

5) 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene film is grown by a solution half-moon shearing method. The device electrodes are then transferred using van der waals transfer methods. Firstly, preparing an organic solution with the concentration of 0.2mg/mL by using a solvent of tetralin and organic molecule powder 2, 9-didecyl dinaphthol [2,3-b:2', 3' -f ] thiophene [3,2-b ] thiophene; then, injecting the solution into the intersection of the substrate and the scraper; the temperature of the substrate and the scraper is set to be 65 ℃, the distance is 100 mu m, the inclination angle of the scraper is 15 ℃, the speed is 2-3 mu m/s, and the scraper is controlled by an electric displacement table to continuously move towards one direction to finish the growth of organic crystals; then spin-coating 1-2 μm polymethyl methacrylate on the patterned device electrode, and baking for 5min at 150 ℃; and then the polymer and the gold electrode are taken off together by utilizing a heat release adhesive tape and then transferred to the organic semiconductor channel layer.

6) And stripping the prepared device from the silicon substrate to obtain the flexible ultrahigh-gain organic amplifier.

Performing an electrical test on the prepared flexible organic amplifier, as shown in fig. 4, wherein a solid line is a voltage transfer characteristic curve of the amplifier, the working voltage is-3V, and the device completes voltage inversion within a range of several millivolts; the dotted line shows the dependence of the gain of the amplifier on the input voltage calculated from the voltage transfer characteristic curve of the amplifier, and it can be seen that the maximum gain value of the amplifier is approximately 10000. The electrical test result shows that the electrical performance of the flexible organic amplifier prepared on the flexible substrate is not inferior to that of a device on the rigid substrate, and the foundation is laid for wearable application of the ultrahigh-gain organic amplifier.

Example 3

A battery powered amplifier module was prepared using the ultra high gain flexible organic amplifier prepared in example 2.

As shown in fig. 5(a), a button cell powered organic amplifier module is combined by combining a 1.5V button cell, two standard resistors with resistance values of 1k Ω and 2k Ω, a flexible polyimide circuit board and a flexible organic amplifier. Fig. 5(b) is a voltage characteristic curve of the amplifier module, which shows that after voltage division by the resistor, the battery supplies 1V to the amplifier, and at this time, the amplifier module can operate normally, and the gain exceeds 1000. Therefore, the ultrahigh-gain organic amplifier can realize battery driving, and lays a foundation for the realization of low-voltage working organic wearable electronic equipment.

Example 4

The ultrahigh-gain flexible organic amplifier prepared in example 2 was used to detect and amplify human electrocardiosignals.

Referring to fig. 6(a), the conductive gel is applied to the skin (as indicated in the figure) near the heart of the human body, the electrocardiographic signals are introduced into the input end of the amplifier, and the output signal of the amplifier is collected at the output end by using a voltmeter. In this case, V + is connected to the input terminal and V-is connected in series with an adjustable voltage source for adjusting the baseline of the input signal.

An adult male (31 years old) is selected as an electrocardio monitoring target, and the working voltage of an amplifier is set to be 1V. FIG. 6(b) is the electrocardiogram of human body amplified by organic amplifier, wherein P, Q, R, S, T and U wave are clearly observed. The amplitude of the electrocardiosignal exceeds 350mV, the amplification factor is about 324 times, and the signal-to-noise ratio is 42 dB. Therefore, the performance parameters of the organic amplifier such as working voltage, amplification factor, signal-to-noise ratio and the like are obviously superior to those of the similar structures reported at present, and the organic amplifier has obvious advantages in the aspect of human biological signal amplification, thereby showing that the organic amplifier has great application prospect in the field of wearable medical electronics.

Example 5

The ultra-high gain flexible organic amplifier prepared in example 2 was used to monitor cardiac electrical signals from patients with a history of atrial fibrillation to aid in clinical diagnosis.

Referring to fig. 6(a), the conductive gel is applied to the skin (as indicated in the figure) near the heart of the human body, the electrocardiographic signals are introduced into the input end of the amplifier, and the output signal of the amplifier is collected at the output end by using a voltmeter. In this case, V + is connected to the input terminal and V-is connected in series with an adjustable voltage source for adjusting the baseline of the input signal.

An elderly male (80 years old) with a history of atrial fibrillation was selected as the target for electrocardiographic monitoring, and the operating voltage of the amplifier was set to 1V. FIG. 7(a) is the patient's ECG signal acquired using a clinical electrocardiograph (NIHON KOHDEN ECG-1350P) without visible atrial fibrillation waves (f-waves). FIG. 7(b) is the ECG signal of a patient collected by the flexible organic amplifier of the present invention, and a distinct f-wave with a frequency of 357bpm is observed, indicating that atrial fibrillation still exists in the patient. The result shows that the ultrahigh-gain flexible organic amplifier has the capability of detecting weak f-waves, even exceeds the electrocardio equipment used in clinic at present to a certain extent, and has the potential of being effectively supplemented in clinical electrocardio diagnosis at present.