An active pH detection device based on interface barrier adjustment and a method thereof

Abstract

The application discloses an active pH detection device based on interface barrier adjustment and a method thereof. The device comprises an energy driving unit for converting mechanical energy into an electric signal; and a sensing and sensitizing unit electrically connected with the energy driving unit. The sensing and sensitizing unit comprises a semiconductor channel with lead-out electrodes arranged at two ends of the semiconductor channel; and a charge sensing and interface barrier adjustment layer wrapped on the surface of the semiconductor channel, for sensing ion concentration change in a to-be-detected solution, changing carrier transport impedance of the semiconductor channel through interface barrier adjustment effect, thereby modulating the electric signal amplitude from the energy driving unit, and outputting a response electric signal varying with the ion concentration.

Description

Technical Field

[0001] This invention relates to the field of nanoenergy and sensor technology, specifically to an active pH detection device and method based on interface barrier modulation. Background Technology

[0002] With the widespread adoption of portable electronic devices, wearable medical monitoring, and distributed environmental sensors, achieving energy self-sufficiency for these miniaturized electronic systems has become a key issue restricting their further development. Nanogenerators, as devices capable of harvesting weak mechanical energy from the environment and converting it into electrical energy, provide an ideal solution for building self-powered sensing systems.

[0003] In the field of piezoelectric energy harvesting, polyvinylidene fluoride (PVDF) and its copolymers are highly favored due to their excellent flexibility, chemical stability, and high piezoelectric coefficient. However, the preparation of traditional PVDF-based piezoelectric materials typically requires complex high-voltage electric field polarization to induce the orientation of internal dipoles. This process not only places stringent requirements on equipment and carries high operational risks, but also makes it difficult to achieve continuous, large-area film fabrication, severely limiting its industrial application in flexible electronics. Furthermore, single organic or inorganic piezoelectric materials often face the contradiction of limited output performance or high mechanical brittleness, making it difficult to provide long-term stable energy output to drive high-precision sensors.

[0004] In the field of pH chemical sensing, while sensors based on semiconductor nanostructures such as zinc oxide (ZnO) offer advantages such as fast response speeds, they still have significant drawbacks in practical applications. First, zinc oxide exhibits poor chemical stability in strongly acidic or alkaline buffer solutions, easily dissolving and leading to device failure. Second, most existing self-powered pH sensors employ a passive detection mode, directly recording the weak signal converted from chemical energy. In this mode, due to the lack of active control over the charge distribution and potential barrier height at the sensing interface, the system's sensitivity to minute changes in pH is insufficient, and it is easily affected by environmental noise. Summary of the Invention

[0005] To address the technical challenges of existing self-powered sensing systems, such as complex polarization processes, poor chemical stability of zinc oxide materials in acidic and alkaline environments, and low sensitivity due to passive sensing modes, this invention provides an active pH detection device and method based on interface barrier modulation. By inducing polymer self-polarization using one-dimensional nanomaterials, the high-voltage polarization step is eliminated. Simultaneously, by constructing an active signal modulation mechanism, the sensitivity and stability of pH detection are significantly improved by utilizing the interface barrier modulation effect.

[0006] According to one aspect of the present invention, an active pH detection device based on interface barrier modulation is provided, comprising: An energy drive unit is used to convert mechanical energy into electrical signals; The sensing enhancement unit is electrically connected to the energy driving unit; The sensing enhancement unit includes: A semiconductor channel with lead-out electrodes at both ends; A charge sensing and interface barrier modulation layer is coated on the surface of the semiconductor channel to sense changes in ion concentration in the test solution. By changing the carrier transport impedance of the semiconductor channel through the interface barrier modulation effect, the amplitude of the electrical signal from the energy drive unit is modulated, and a response electrical signal that changes with ion concentration is output.

[0007] As a further technical solution, the energy driving unit is a flexible composite piezoelectric generator, comprising a piezoelectric polymer matrix and a one-dimensional piezoelectric nanomaterial dispersed in the piezoelectric polymer matrix.

[0008] As a further technical solution, the piezoelectric polymer matrix is ​​polyvinylidene fluoride, the one-dimensional piezoelectric nanomaterial is zinc oxide nanowire, and the mass ratio of zinc oxide nanowire to polyvinylidene fluoride is in the range of (0.05-0.2):1.

[0009] As a further technical solution, the energy-driven unit has self-polarization characteristics: the polar charge on the surface of the zinc oxide nanowires interacts with the polar charge in the polyvinylidene fluoride molecular chain. Group interactions induce the formation of a piezoelectric β phase in polyvinylidene fluoride in situ.

[0010] As a further technical solution, the semiconductor channel is a single zinc oxide microwire, horizontally fixed on an insulating substrate.

[0011] As a further technical solution, the charge sensing and interface barrier adjustment layer is a polymethyl methacrylate film with a thickness of 20nm-200nm.

[0012] As a further technical solution, the working mechanism of the interface barrier modulation effect is as follows: The regulating layer senses H+ or OH- ions in the solution to be tested and induces charge redistribution at the interface; The interface barrier modulation effect generated by the charge redistribution changes the depletion layer width inside the semiconductor channel through field-effect coupling, thereby modulating the carrier transport impedance.

[0013] As a further technical solution, the self-polarization characteristic of the energy-driven unit is achieved in the following way: The zinc oxide nanowires are uniformly distributed within the polyvinylidene fluoride (PVDF) matrix, forming a nanowire-polymer interface. The polar charges on the surface of the zinc oxide nanowires induce polar charges in the PVDF molecular chains during solvent evaporation. The groups are oriented to form a piezoelectric β phase spontaneously, without the need for external high-voltage electric field polarization.

[0014] According to one aspect of the present invention, an active pH detection method using the aforementioned device is provided, comprising the following steps: The sensing and sensitizing unit is placed in the solution to be tested, so that the charge sensing and interface barrier adjustment layer sense the change in ion concentration. A mechanical excitation is applied to the energy drive unit to generate an initial electrical pulse signal; The initial electrical pulse signal is modulated by the sensing enhancement unit to output a response electrical signal that changes with the ion concentration. The amplitude shift of the response electrical signal is collected and analyzed, and the pH value of the solution to be tested is obtained according to the preset voltage-pH calibration curve.

[0015] This invention also provides the application of the active pH detection device based on interface barrier regulation in the preparation of wearable motion monitoring devices, flexible biomedical devices, or real-time water quality monitoring systems.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: First, active signal modulation and high sensitivity. This invention employs an active sensing mode of "excitation-modulation." The energy-driven unit generates a stable initial electrical pulse signal as the excitation source. The charge sensing and interface barrier adjustment layer in the sensing enhancement unit sense H+ or OH- ions in the test solution, inducing charge redistribution at the interface. This redistributes the charge through field-effect coupling, altering the width of the depletion layer inside the semiconductor channel, thereby modulating the carrier transport impedance and causing the output electrical signal amplitude to change with ion concentration. This mechanism transforms pH changes into controllable modulation of the electrical signal amplitude, significantly improving detection sensitivity, especially exhibiting excellent response characteristics in the pH range of 6-12. This solves the technical problems of insufficient sensitivity and susceptibility to environmental noise interference in traditional passive sensing modes.

[0017] Second, simplified process and self-polarizing characteristics. In this invention, the energy-driven unit employs a composite structure of zinc oxide nanowires and polyvinylidene fluoride (PVDF). This is achieved through the polar charge on the surface of the zinc oxide nanowires interacting with the molecular chains of PVDF. The interaction of functional groups induces the formation of a piezoelectric β phase in polyvinylidene fluoride (PVDF) in situ during solvent evaporation, achieving self-polarization. This design eliminates the need for high-voltage electric field polarization treatment required in the preparation of traditional piezoelectric materials, greatly simplifying the preparation process, reducing equipment costs and operational risks, and facilitating large-scale industrial production.

[0018] Third, the self-powered system is integrated and applicable to multiple scenarios. This invention integrates the energy driving unit and the sensing enhancement unit into one unit. The energy driving unit can convert environmental mechanical energy (such as human movement, vibration, and pressure) into electrical energy, directly powering the sensing enhancement unit without the need for an external power source or energy storage device, thus achieving true self-powered detection. Simultaneously, all functional layers are made of flexible polymer materials, possessing excellent biocompatibility and mechanical flexibility, making them widely applicable in wearable motion monitoring, flexible biomedicine, real-time water quality monitoring, and other scenarios.

[0019] Fourth, chemical stability and long lifespan. This invention incorporates a charge sensing and interface barrier adjustment layer in the sensing enhancement unit, preferably a polymethyl methacrylate film with a thickness of 20nm-200nm. This layer acts as a physical shielding layer, effectively preventing the zinc oxide microwires from dissolving in acidic or alkaline solutions. This solves the long-standing problem of traditional ZnO-based semiconductor sensors being susceptible to corrosion in aqueous solutions, significantly improving the sensor's lifespan and reliability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of an active pH detection device based on interface barrier modulation, provided in an embodiment of the present invention; wherein the left side is an energy driving unit that provides an excitation signal, and the right side is a sensing enhancement unit placed in the environment to be measured.

[0022] In the figure: 1—PDMS encapsulation layer, 2—upper electrode, 3—ZnO / PVDF self-polarizing composite film, 4—lower electrode, 5—charge sensing and interface barrier modulation layer, 6—ZnO micrometer wire, 7—pH buffer solution to be tested. Detailed Implementation

[0023] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0025] To address the pressing challenges in the fields of energy harvesting and self-powered sensing, this invention provides a highly efficient flexible nanogenerator that eliminates the need for traditional polarization processes and possesses self-polarization characteristics. Based on this, an active pH detection device capable of actively adjusting the interfacial barrier and exhibiting high chemical stability and high sensitivity is constructed.

[0026] Example 1

[0027] This embodiment provides an active pH detection device based on interface barrier modulation, such as... Figure 1 As shown, the device includes an energy-driven unit and a sensing enhancement unit.

[0028] The core of the energy-driven unit lies in achieving self-polarization using the interface charge-induced effect, eliminating the need for external polarization. Its fabrication includes:

[0029] 1. Material selection and mixing:

[0030] One-dimensional zinc oxide (ZnO) nanowires were selected as the structure-inducing and reinforcing phase.

[0031] Polyvinylidene fluoride (PVDF) was selected as the piezoelectric polymer matrix.

[0032] Ratio control: Add ZnO nanowires and PVDF to an organic solvent at a mass ratio of 0.05-0.2:1 (preferably 0.1:1), such as to 15 mL of N,N-dimethylformamide (DMF) solvent.

[0033] 2. Dispersed processing:

[0034] The mixed solution is treated with ultrasonic dispersion technology (such as probe ultrasonication or water bath ultrasonication) for 30 minutes to form a uniform non-agglomerated network of ZnO nanowires in the polymer matrix.

[0035] 3. Self-polarizing film formation:

[0036] The mixture is poured into a flat mold using a solution casting method.

[0037] Drying at a controlled temperature (e.g., 60℃-100℃) utilizes the attraction of the polar charge on the ZnO surface to the PVDF molecular chain during solvent evaporation to induce the spontaneous formation of the piezoelectric phase, thus eliminating the need for the conventional high-voltage electric field polarization step and forming a self-polarized composite piezoelectric thin film 3.

[0038] 4. Electrodes and Packaging:

[0039] Metal electrodes (upper electrode 2 and lower electrode 4) are fabricated on both sides of the thin film, and the entire device is encapsulated using a flexible polymer (such as polydimethylsiloxane PDMS) to form a PDMS encapsulation layer 1 to protect the device from mechanical damage, thereby forming an energy drive unit.

[0040] The core of the sensing enhancement unit lies in improving the chemical stability and sensitivity of the sensor through an interface barrier adjustment layer, the fabrication of which includes:

[0041] 1. Fabrication of the sensing channel:

[0042] Select a single zinc oxide micron wire 6, bridging it across a flexible or rigid insulating substrate, and lead out an electrode connection.

[0043] 2. Modification of charge sensing and interface barrier modulation layer 5:

[0044] A polymethyl methacrylate (PMMA) film is coated on the surface of zinc oxide microwires, with the thickness controlled in the range of 20nm-200nm.

[0045] This charge sensing and interface barrier conditioning layer serves two purposes: firstly, as a physical shielding layer to prevent zinc oxide from directly contacting the corrosive test solution; and secondly, as a sensing interface to change the charge distribution by adsorbing ions from the solution.

[0046] 3. System Integration:

[0047] The output of the energy-driven unit is electrically connected to the input of the sensing and sensitizing unit via wires. The initial electrical pulse signal generated by the energy-driven unit under external mechanical excitation is transmitted to the sensing and sensitizing unit. The charge sensing and interface barrier adjustment layer in the sensing and sensitizing unit modulates the amplitude of the electrical signal and outputs a response electrical signal that changes with the pH value, thus forming the active pH detection device.

[0048] Example 2

[0049] This embodiment is used to verify the active modulation effect of charge induction and interface barrier modulation layer on electrical signals.

[0050] Experimental design: The active pH detection device prepared in Example 1 was used, and a control group was set up for comparative experiments.

[0051] Control group A: The sensing enhancement unit is not covered with a PMMA layer (i.e., there is no charge sensing and interface barrier adjustment layer), and the zinc oxide microwires are directly exposed.

[0052] Control group B: The sensing enhancement unit is covered with a PMMA layer, but a passive detection mode is used, that is, the electrical signal of chemical energy conversion is directly recorded without using the excitation signal provided by the energy drive unit.

[0053] Experimental group: The complete device prepared in Example 1 was used. The energy driving unit generates an excitation signal, and the sensing enhancement unit actively modulates the excitation signal.

[0054] Test method: Place each group of sensors in buffer solutions with pH values ​​of 6, 7, 8, 9, 10, 11, and 12 respectively, and record the amplitude of the output electrical signal.

[0055] The test results are shown in Table 1.

[0056] Table 1. Active modulation effect of charge induction and interface barrier modulation layer on electrical signals

[0057] Control group A Signal drifts severely, unable to obtain stable amplitude (device deteriorates rapidly in buffer) N / A Extremely low Control group B Several millivolts to microvolts, relying only on chemical potential energy conversion Slow (>5 s), waiting for ion diffusion and interface chemical equilibrium Low (easily submerged by environmental electromagnetic noise) Experimental group About 10 mV → 70 mV (significant stepwise amplitude modulation with increasing pH) <1s (transient impulse response) High (>20 dB), clear and distinct pulse peak

[0058] Results analysis:

[0059] For control group A (without PMMA layer): the zinc oxide microwires were directly exposed to buffer solutions of different pH values. Because ZnO readily dissolves in acidic and alkaline environments, the physical structure of the semiconductor channel was damaged. During testing, this manifested as impaired carrier transport channels, severe signal drift, and rapid decay to zero, making continuous and stable voltage amplitude acquisition impossible. This conversely demonstrates that the fundamental physical shielding function of the PMMA layer is a prerequisite for subsequent device testing.

[0060] For control group B (PMMA layer + passive detection mode): In passive mode, the device is not connected to an energy drive unit, and only converts the change in solution ion concentration into weak chemical potential energy or intrinsic piezoelectric potential. Due to the lack of active external bias or excitation electric field, the interfacial barrier change generated by ion adsorption on the PMMA layer surface is difficult to effectively penetrate and deeply deplete the charge carriers inside ZnO, resulting in an output signal in the extremely low microvolt / low millivolt range, and a long response time to reach steady state, which is easily masked by electromagnetic noise in the environment (low signal-to-noise ratio). At this time, PMMA mainly acts as a simple "protective layer".

[0061] For the experimental group (PMMA layer + active modulation mode): when an initial pulse signal of up to 6.9V is introduced as a high-energy excitation source by an energy-driven unit, the function of the PMMA layer undergoes a qualitative change. At this point, the PMMA layer is not merely a protective layer, but also a "charge-sensing and interface barrier modulation layer." When the high-energy pulse signal flows through the ZnO channel, the local electric field generated by the exogenous ions sensed by the PMMA layer can produce strong field-effect coupling, deeply modulating the depletion layer width (effective impedance) of the ZnO channel. Therefore, the output response pulse exhibits a clear, wide-amplitude stepped response from approximately 10 mV to 70 mV in the pH range of 6 to 12, with fast response time and extremely high signal-to-noise ratio.

[0062] Example 3

[0063] This embodiment verifies the rationality and necessity of the PMMA thickness range (20nm-200nm) by comparing the physical stability and electrical response characteristics of sensors with different thicknesses.

[0064] When the PMMA thickness is less than 20 nm, the polymer film is too thin, making it difficult to form a completely dense, non-porous physical shielding layer during fabrication. In actual testing, acid-base buffer solutions can easily penetrate through the microscopic defects of the film, directly reacting with the underlying zinc oxide microwires and causing them to dissolve. This results in the device losing its conductive channel in a very short time, completely failing to meet the long-term stability testing requirements of over 100 hours, and causing the device to fail rapidly.

[0065] When the PMMA thickness is in the range of 20nm-200nm (e.g., 100nm), the film thickness achieves the optimal balance between physical protection and electrical modulation. On one hand, the dense and continuous PMMA layer can effectively isolate strong acid and alkali solutions, completely solving the problem of semiconductor sensors being susceptible to corrosion and ensuring that the device remains highly stable during continuous cyclic testing for more than 100 hours. On the other hand, this thickness range is precisely within the effective field-effect coupling distance. The charge accumulation of solution ions at the interface can generate an electric field without attenuation, deeply penetrating the film and modulating the width of the depletion layer inside zinc oxide, thereby achieving highly sensitive, wide-amplitude millivolt-level voltage modulation to pH changes with rapid response.

[0066] When the PMMA thickness exceeds 200 nm, although the physical protection capability is further enhanced, the excessive thickness of the insulating dielectric layer causes the local electric field generated by the interface charge to attenuate drastically as it penetrates the PMMA layer to reach the zinc oxide surface. Because this exceeds the effective Debye shielding and field-effect coupling distance, the interface barrier modulation effect is significantly weakened or rendered ineffective. Macroscopically, this manifests as a sharp decrease in the device's sensitivity to pH concentration changes, negligible amplitude modulation of the output voltage, and a significant slowdown in response time due to prolonged ion diffusion and polarization time, thus negating the significance of active high-sensitivity detection.

[0067] Example 4

[0068] This embodiment is used to verify the self-polarization characteristics of the energy drive unit, proving that the piezoelectric effect can be generated without the need for external high-voltage electric field polarization.

[0069] (1) Verification of crystal phase structure ( (Successful induction of phase)

[0070] The prepared sample A (ZnO / PVDF composite self-polarized thin film) was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The test results show that the XRD pattern... A strong diffraction peak appears at this location, clearly corresponding to the piezoelectric element. The (200) crystal plane of the phase. Meanwhile, FTIR testing confirmed the presence of 512, 606, 838, and... The wavenumber peaks at these locations are all characteristic piezoelectric peaks. Phase vibration peaks. This confirms from a microscopic mechanism that during the solvent evaporation and film formation process, the polar charges on the surface of zinc oxide nanowires actively interact with the PVDF molecular chains. Strongly electronegative groups undergo charge interactions. Through surface charge-induced polarization and nano-confinement effects, the directional alignment of internal dipoles was successfully promoted, resulting in a high content of piezoelectricity spontaneously formed in situ. Mutually.

[0071] (2) Comparison of electrical output performance (macroscopic manifestation of self-polarization effect):

[0072] To verify the actual electrical gain of self-polarization, sample A and sample B (pure PVDF film without the addition of one-dimensional piezoelectric nanomaterials, whose internal dipoles are in a random orientation state) were compared under the same uniaxial mechanical compression excitation.

[0073] Sample B, which did not undergo effective polarization, exhibited extremely weak piezoelectric activity, with an open-circuit voltage of only about 60 mV and a short-circuit current of about 30 nA. In contrast, sample A, possessing self-polarization properties, demonstrated exceptionally superior energy conversion performance, with its maximum open-circuit voltage jumping to approximately 6.9 V and its short-circuit current reaching 0.96 nA. The electrical output performance has been improved by more than two orders of magnitude, which fully demonstrates the effectiveness of the self-polarization effect.

[0074] (3) Verification of self-polarization completeness (no external polarization required):

[0075] To further confirm that the composite thin film has completely completed the polarization process, a conventional high-voltage electric field polarization treatment (e.g., 5.5 kV for 36 hours) was applied to the molded sample A. Comparative testing revealed that the electrical output performance of the device after high-voltage polarization treatment did not show a significant improvement compared to the original sample A without external high-voltage treatment. This extreme verification result directly proves that the composite thin film described in this application has spontaneously and fully completed its internal polarization behavior, thus completely eliminating the need for stringent high-voltage polarization processes in industrial production.

[0076] Example 5

[0077] This embodiment describes in detail the specific operation process of active pH detection using the device described in Embodiment 1.

[0078] 1. Pre-sensing processing:

[0079] The sensing enhancement unit is placed in the pH buffer solution 7 to be tested, so that the PMMA interface barrier adjustment layer can fully sense the concentration of H+ or OH- ions in the solution.

[0080] 2. Generation of excitation signal

[0081] A periodic mechanical excitation (such as pressing or bending) is applied to the energy drive unit, generating an initial voltage pulse signal. The energy drive unit converts mechanical energy into an initial electrical pulse signal, which is transmitted to the sensing enhancement unit via a wire. This pulse signal flows through the sensing enhancement unit, and its amplitude is modulated by the real-time impedance of the sensing enhancement unit.

[0082] 3. Active signal modulation

[0083] When the initial electrical pulse signal flows through the sensing enhancement unit, the carrier transport impedance of the zinc oxide microwire channel is modulated by the interface barrier modulation effect. Specifically, the change in ion concentration induced by the PMMA layer alters the depletion layer width inside the zinc oxide microwire through field-effect coupling, thereby changing the channel resistance and modulating the amplitude of the electrical signal.

[0084] The enhancement and modulation mechanisms are as follows:

[0085] Expected response: When the pH of the solution changes, the ion concentration sensed at the PMMA interface changes accordingly, adjusting the depletion layer width of the ZnO microwires through the field effect.

[0086] Signal performance: A decrease in pH value (increased acidity) or an increase in pH value (increased alkalinity) will cause a corresponding shift in the impedance of the ZnO channel, thereby acquiring amplitude-modulated pulse voltages of different amplitudes at the output terminal.

[0087] 4. Data Acquisition and Processing

[0088] The amplitude of the output response electrical signal was collected, and the measurement was repeated three times for each pH value, with the average value taken. Using pH7 as a reference point, the output voltage offset at different pH values ​​was recorded.

[0089] The test results are shown in Table 2.

[0090] Table 2 Output voltage offset at different pH values

[0091] 6 0.010 -0.008 7 0.018 0 8 0.020 +0.002 9 0.022 +0.004 10 0.025 +0.007 11 0.035 +0.017 12 0.070 +0.052

[0092] 1. Verification of detection patterns and expected results

[0093] Test data shows that as the pH of the test solution gradually increases from 6 to 12 (from weakly acidic to strongly alkaline), the amplitude of the output response pulse voltage of the active pH detection device significantly increases from 0.010 V to 0.070 V. Using a neutral environment (pH=7, output voltage 0.018 V) as a reference point, the output voltage exhibits a significant monotonic positive shift trend with increasing pH and a negative shift with decreasing pH, successfully establishing a clear voltage-pH calibration response relationship.

[0094] 2. Demonstration of the core mechanism (physical basis for superior performance compared to existing technologies): This stepped wide-amplitude voltage modulation phenomenon directly confirms the core mechanism of this application—"active interface barrier regulation".

[0095] In an alkaline environment (high pH): the PMMA conditioning layer surface senses and adsorbs negatively charged OH- ions. Through strong field-effect coupling, this significantly increases the width of the depletion layer inside the semiconductor channel (zinc oxide microwire), leading to a sharp increase in the channel carrier transport impedance. Therefore, the initial electrical pulse from the energy-driven unit generates an extremely high potential drop here, modulating a high-amplitude pulse voltage (e.g., 0.070 V at pH 12).

[0096] In an acidic environment (low pH): the accumulation of H+ ions leads to a narrowing of the depletion layer thickness, which in turn reduces the channel impedance, resulting in a corresponding decrease in the output voltage amplitude.

[0097] 5. Expected performance range:

[0098] Energy output: At frequencies corresponding to normal human activities (such as walking and tapping), the system is expected to output an open-circuit voltage in the range of 1V-10V, which is sufficient to drive more than 5 low-power LED indicators or miniature sensing circuits.

[0099] Sensing stability: Due to the protection of the PMMA layer, the response signal fluctuation of the sensor should remain at a low level during continuous cyclic testing in the pH range of 6-12.

[0100] Example 6

[0101] This embodiment demonstrates the practical application effect of the active pH detection device of the present invention in different application scenarios.

[0102] 6.1 Wearable motion monitoring applications

[0103] The device prepared in Example 1 was integrated into the insole of a sports shoe. The energy drive unit was placed in the heel pressure area, and the sensing and amplification unit was placed in the forefoot area of ​​the insole and exposed to the sweat environment of the sole of the foot.

[0104] Test method: Subjects walk at a constant speed on a treadmill for a set time, and the amplitude of the output electrical signal is recorded in real time. The pH value of the foot sweat is calculated based on a pre-established voltage-pH calibration curve.

[0105] Expected Results: During walking, the energy-driven unit generates sufficient pulse voltage when the heel strikes the ground to power the sensing and sensitizing unit. Monitoring results show that the pH value of sweat initially decreases and then increases during exercise. This trend is consistent with the lactic acid secretion pattern in exercise physiology, indicating that this device can be used for exercise status monitoring and fatigue assessment.

[0106] 6.2 Application of Real-time Water Quality Monitoring

[0107] The sensor enhancement unit is fixed in the water flow channel, and the energy drive unit provides the excitation signal by hand-pressing, which is used for rapid water quality detection in the field.

[0108] Test method: Four types of water samples were collected: tap water, rainwater, river water, and lake water. The pH value was measured using this device and compared with the reading of a standard pH meter.

[0109] Expected Results: The device's detection results show good agreement with standard pH meter readings, and the detection error meets the application requirements for rapid water quality testing. The energy-driven unit is triggered by water flow impact, buoy vibration, or periodic mechanical disturbance to generate an initial electrical pulse. The sensing enhancement unit is immersed in the water sample for real-time sensing. Due to the 20nm-200nm PMMA layer as physical shielding, the zinc oxide microwires are protected from direct corrosion in various complex water qualities, maintaining long-term stability. When the pH value of the water fluctuates due to acid rain or industrial wastewater discharge, the amplitude of the pulse voltage output by the device will show a corresponding significant shift at the millivolt level. This mode greatly reduces the dependence on fixed power supplies and periodic probe replacements found in traditional water quality pH meters, making it particularly suitable for building distributed, maintenance-free field sensor networks.

[0110] 6.3 Flexible Biomedical Applications

[0111] The device prepared in Example 1 was encapsulated in a flexible biocompatible material, and the surface of the sensing and sensitizing unit was covered with a semi-permeable membrane for pH monitoring of in vitro cell culture medium.

[0112] Test method: Place the device in a cell culture incubator, continuously monitor the pH changes of the cell culture medium, and record the data at set time intervals.

[0113] Expected Results: During continuous monitoring, the device output voltage remained stable, and the pH value display range was consistent with the normal pH fluctuation range of the cell culture medium. The device did not adversely affect cell growth, indicating that it has good biocompatibility and meets the basic requirements for biomedical applications.

[0114] In summary, this invention discloses an active pH detection device and method, belonging to the field of nanoenergy and sensor technology. The device consists of an energy-driven unit and a sensing enhancement unit connected in parallel. The energy-driven unit employs a hybrid composite film composed of zinc oxide nanowires and polyvinylidene fluoride (PVDF) at a mass ratio of 0.05-0.2:1, achieving polarization-free self-polarization characteristics through interfacial charge induction. The sensing enhancement unit comprises a single zinc oxide microwire coated with a 20nm-200nm thick polymethyl methacrylate (PMMA) interfacial barrier modulation layer. The method of this invention uses a pulsed electrical signal generated by mechanically stimulating the energy-driven unit as an excitation source. It utilizes the impedance shift of the sensing unit caused by pH changes to actively modulate the pulse voltage amplitude for detection. This invention has advantages such as simple preparation process, no need for external high-voltage polarization, high chemical stability, and good sensing sensitivity.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. An active pH detection device based on interface barrier modulation, characterized in that, include: An energy drive unit is used to convert mechanical energy into electrical signals; The sensing enhancement unit is electrically connected to the energy driving unit; The sensing enhancement unit includes: A semiconductor channel with lead-out electrodes at both ends; A charge sensing and interface barrier modulation layer is coated on the surface of the semiconductor channel to sense changes in ion concentration in the test solution. By changing the carrier transport impedance of the semiconductor channel through the interface barrier modulation effect, the amplitude of the electrical signal from the energy drive unit is modulated, and a response electrical signal that changes with ion concentration is output.

2. The active pH detection device based on interface barrier modulation according to claim 1, characterized in that, The energy drive unit is a flexible composite piezoelectric generator, comprising a piezoelectric polymer matrix and a one-dimensional piezoelectric nanomaterial dispersed in the piezoelectric polymer matrix.

3. The active pH detection device based on interface barrier modulation according to claim 2, characterized in that, The piezoelectric polymer matrix is ​​polyvinylidene fluoride, and the one-dimensional piezoelectric nanomaterial is zinc oxide nanowire, with the mass ratio of zinc oxide nanowire to polyvinylidene fluoride ranging from (0.05-0.2):

1.

4. The active pH detection device based on interface barrier modulation according to claim 3, characterized in that, The energy-driven unit has self-polarization characteristics: the polar charge on the surface of the zinc oxide nanowires interacts with the polar charge in the polyvinylidene fluoride molecular chain. Group interactions induce the formation of a piezoelectric β phase in polyvinylidene fluoride in situ.

5. The active pH detection device based on interface barrier regulation according to claim 1, characterized in that, The semiconductor channel is a single zinc oxide microwire, horizontally fixed on an insulating substrate.

6. The active pH detection device based on interface barrier modulation according to claim 1, characterized in that, The charge sensing and interface barrier modulating layer is a polymethyl methacrylate film with a thickness of 20nm-200nm.

7. The active pH detection device based on interface barrier modulation according to claim 1, characterized in that, The working mechanism of the interface barrier modulation effect is as follows: The regulating layer senses H+ or OH- ions in the solution to be tested and induces charge redistribution at the interface; The interface barrier modulation effect generated by the charge redistribution changes the depletion layer width inside the semiconductor channel through field-effect coupling, thereby modulating the carrier transport impedance.

8. The active pH detection device based on interface barrier modulation according to claim 3 or 4, characterized in that, The self-polarization characteristic of the energy-driven unit is achieved in the following way: The zinc oxide nanowires are uniformly distributed within the polyvinylidene fluoride (PVDF) matrix, forming a nanowire-polymer interface. The polar charges on the surface of the zinc oxide nanowires induce polar charges in the PVDF molecular chains during solvent evaporation. The groups are oriented to form a piezoelectric β phase spontaneously, without the need for external high-voltage electric field polarization.

9. An active pH detection method using the device according to any one of claims 1-8, characterized in that, Includes the following steps: The sensing and sensitizing unit is placed in the solution to be tested, so that the charge sensing and interface barrier adjustment layer sense the change in ion concentration. A mechanical excitation is applied to the energy drive unit to generate an initial electrical pulse signal; The initial electrical pulse signal is modulated by the sensing enhancement unit to output a response electrical signal that changes with the ion concentration. The amplitude shift of the response electrical signal is collected and analyzed, and the pH value of the solution to be tested is obtained according to the preset voltage-pH calibration curve.

10. The application of the active pH detection device based on interface barrier regulation according to any one of claims 1-8 in the preparation of wearable motion monitoring devices, flexible biomedical devices, or real-time water quality monitoring systems.

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