Wearable bracelet for formaldehyde gas detection

Abstract

The utility model provides a wearable bracelet for formaldehyde gas detection, and belongs to the technical field of detection. The flexible formaldehyde gas sensor comprises a semiconductor sensing chip, a flexible electrode, a copper foil circuit, a binding post, a flexible printed circuit board, a resistor, a signal amplification unit, a microcontroller, a crystal oscillation circuit, a power supply, an LED indicating lamp and a substrate layer, the binding posts are connected with a circuit on the flexible printed circuit board; the resistor, the signal amplification unit, the microcontroller, the crystal oscillation circuit, the power supply and the LED indicating lamp are connected through a circuit on the flexible printed circuit board; the flexible printed circuit board covers the substrate layer; the wrist strap comprises a lock catch, a lock ring and a lock hole. The wearable bracelet disclosed by the utility model is quick in response and simple to operate, and can be used for detecting the formaldehyde content in a daily family environment and monitoring the formaldehyde content in a factory environment in real time.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of detection, specifically relates to a wearable bracelet for formaldehyde gas detection. BACKGROUND

[0002] Formaldehyde (HCHO) is a colorless irritant gas that is ubiquitous in building materials, household products, and cigarette smoke, and is the main cause of indoor air pollution. Exposure to high levels of HCHO can cause respiratory and skin irritation and increase the risk of cancer, especially passive inhalation of cigarette smoke. Although advanced formaldehyde detection methods such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) can provide accurate formaldehyde detection, their high cost and complex operation limit their accessibility. In contrast, commercially available compact detectors provide convenience, but may not match professional tools in terms of sensitivity and stability. Therefore, a high-sensitivity, easy-to-operate, stable, and low-cost real-time room temperature HCHO detection device will have practical value in daily healthcare.

[0003] Currently, the more popular gas sensor on the market is a metal oxide-based chemical resistance type gas sensor, which has the advantages of low cost, simple operation, simple structure, high performance, and environmental protection. However, since high-activity oxygen ions or oxygen species are needed to trigger the reaction of the gas sensor, most metal oxide gas sensors usually require a high operating temperature (200℃-300℃) to achieve high-precision detection and sensitivity. Therefore, current research on metal oxide semiconductor gas sensors mainly focuses on the following two directions: 1) developing gas-sensitive materials that can achieve high selectivity at room temperature and have long-term stability; 2) exploring low-energy or green methods to replace high-temperature heating to trigger gas reactions and improve sensitivity, such as using the photocatalytic effect of semiconductors to generate high-activity electron-hole pairs to trigger the formation of high-activity free radicals from adsorbed oxygen molecules. SUMMARY

[0004] To overcome the shortcomings of the prior art, the utility model aims to provide a wearable bracelet for formaldehyde gas detection based on a flexible formaldehyde gas sensor of semiconductor nanocomposite material, which realizes high sensitivity, easy operation, stability, and low-cost real-time room temperature HCHO detection.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme:

[0006] A wearable bracelet for formaldehyde gas detection includes a flexible formaldehyde gas sensor and a wristband, and the flexible formaldehyde gas sensor is connected to the wristband at both ends.

[0007] The flexible formaldehyde gas sensor comprises a flexible sensing area, a flexible printed circuit board, a terminal device and a substrate layer; the flexible printed circuit board is covered on the substrate layer, and the flexible sensing area and the terminal device are located above the flexible printed circuit board;

[0008] The flexible sensing area comprises a semiconductor sensing chip, a flexible electrode, a copper foil circuit and a terminal post; the semiconductor sensing chip is located above the flexible electrode and partially overlaps and contacts the flexible electrode; one end of the copper foil circuit is connected with the flexible electrode, and the other end is connected with the terminal post; the terminal post is connected with the circuit on the flexible printed circuit board;

[0009] The terminal device comprises a resistor, a signal amplification unit, a microcontroller, a crystal oscillator circuit, a power supply and an LED indicator light; the resistor, the signal amplification unit, the microcontroller, the crystal oscillator circuit, the power supply and the LED indicator light are connected through the circuit on the flexible printed circuit board; the positive and negative electrodes of the power supply are connected with the circuit on the flexible printed circuit board; the power supply provides current for all the circuits on the flexible printed circuit board.

[0010] Further, the substrate layer is flexible polydimethylsiloxane.

[0011] Further, in the flexible sensing area, the semiconductor sensing chip is one and in a circular shape; the flexible electrode is two and in a rhombus shape; the terminal post is two; the semiconductor sensing chip is located in the middle of the two flexible electrodes and above the rhombus corner of the two flexible electrodes.

[0012] Further, the semiconductor sensing chip in the flexible sensing area is a composite structure formed by combining an N-type semiconductor with a P-type semiconductor, and has a silver sulfide shell on the surface.

[0013] Further, the N-type semiconductor is a TiO2 nanotube array, and the P-type semiconductor is a transition metal oxide MnO2.

[0014] Further, the terminal post of the flexible sensing area is connected with the circuit on the flexible printed circuit board through a wire or conductive glue.

[0015] Further, in the terminal device, the resistor is two; and the LED indicator light is a stroboscopic light.

[0016] Further, in the terminal device, the power supply is a 3.3V-5V button cell.

[0017] Further, the wristband comprises a lock buckle, a lock ring and a lock hole; the lock buckle is inserted into the lock hole through the lock ring; and the wristband is detachable and replaceable.

[0018] Further, the wristband is made of silicone or leather.

[0019] The utility model has the advantages of

[0020] The utility model relates to a wearable bracelet for formaldehyde gas detection, which is suitable for detecting trace (ppb level) harmful formaldehyde gas in the atmospheric environment. The flexible formaldehyde gas sensor utilizes the combination of various semiconductor materials with heterostructures to obtain a composite substrate with high efficient electron transfer efficiency, realizing formaldehyde gas resistance sensing under normal temperature conditions. Even when other gases are present, the formaldehyde gas can be accurately detected. The problem that the existing resistance sensor needs to work under high temperature conditions is effectively solved. Through flexible design, the wearable bracelet can be easily worn on the human body. The device is fast in response and simple in operation, and can be used for detecting the formaldehyde content in the daily household environment and real-time monitoring the formaldehyde content in the factory environment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The utility model relates to a wearable bracelet for formaldehyde gas detection, which is suitable for detecting trace (ppb level) harmful formaldehyde gas in the atmospheric environment. The flexible formaldehyde gas sensor utilizes the combination of various semiconductor materials with heterostructures to obtain a composite substrate with high efficient electron transfer efficiency, realizing formaldehyde gas resistance sensing under normal temperature conditions. Even when other gases are present, the formaldehyde gas can be accurately detected. The problem that the existing resistance sensor needs to work under high temperature conditions is effectively solved. Through flexible design, the wearable bracelet can be easily worn on the human body. The device is fast in response and simple in operation, and can be used for detecting the formaldehyde content in the daily household environment and real-time monitoring the formaldehyde content in the factory environment.

[0022] Figure 2 The utility model relates to a wearable bracelet for formaldehyde gas detection, which is suitable for detecting trace (ppb level) harmful formaldehyde gas in the atmospheric environment. The flexible formaldehyde gas sensor utilizes the combination of various semiconductor materials with heterostructures to obtain a composite substrate with high efficient electron transfer efficiency, realizing formaldehyde gas resistance sensing under normal temperature conditions. Even when other gases are present, the formaldehyde gas can be accurately detected. The problem that the existing resistance sensor needs to work under high temperature conditions is effectively solved. Through flexible design, the wearable bracelet can be easily worn on the human body. The device is fast in response and simple in operation, and can be used for detecting the formaldehyde content in the daily household environment and real-time monitoring the formaldehyde content in the factory environment.

[0023] The meanings of the reference signs are explained as follows:

[0024] 1, flexible formaldehyde gas sensor; 2, wrist strap;

[0025] 101, semiconductor sensing chip; 102, flexible electrode; 103, copper foil circuit; 104, terminal post; 105, resistor; 106, signal amplification unit; 107, microcontroller; 108, crystal oscillator circuit; 109, power supply; 110, LED indicator; 111, flexible printed circuit board. DETAILED DESCRIPTION

[0026] The following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the claimed utility model, but only represents selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the utility model.

[0027] The utility model will be described in detail in conjunction with the embodiments.

[0028] Embodiment 1

[0029] The utility model provides a wearable bracelet for formaldehyde gas detection, as shown in Figure 1 , Figure 2 , including: flexible formaldehyde gas sensor 1 and wrist strap 2, flexible formaldehyde gas sensor 1 both ends are connected with wrist strap 2.

[0030] The flexible formaldehyde gas sensor includes: a flexible sensing area, a flexible printed circuit board 111, a terminal device, and a substrate layer; the flexible printed circuit board 111 covers the substrate layer, and the flexible sensing area and the terminal device are located on the flexible printed circuit board 111; the substrate layer is flexible polydimethylsiloxane.

[0031] The flexible sensing area includes: one semiconductor sensing chip 101, two flexible electrodes 102, a copper foil circuit 103, and two terminals 104. The flexible electrodes 102 and the terminals 104 are connected by the copper foil circuit 103. The terminals 104 are connected to the circuit on the flexible printed circuit board 111 by wires or conductive adhesive. The semiconductor sensing chip 101 is circular, and the flexible electrodes 102 are rhomboid. The semiconductor sensing chip 101 is located in the middle of the two flexible electrodes 102 and is positioned above one corner of the rhomboid shape of the two flexible electrodes 102.

[0032] The semiconductor sensor chip is a composite structure formed by combining an N-type semiconductor TiO2 nanotube array with a P-type semiconductor transition metal oxide MnO2, and has a silver sulfide shell on its surface.

[0033] TiO2 is used to construct nanotube arrays. As an N-type semiconductor, TiO2 is chemically stable, has strong catalytic activity, is unaffected by strong acid and alkali conditions, is non-toxic, and is inexpensive, making it widely used in photocatalysis and energy fields. However, TiO2 has an excessively wide band gap (3.2 eV), resulting in insufficient absorption of ultraviolet light, low conductivity, and weak charge transfer efficiency. Therefore, this invention introduces other substances or constructs composite structures to improve its performance. The pn heterojunction theory proposed by Shockley is used to improve the surface charge density of TiO2 to a certain extent, thereby increasing the charge transfer efficiency. Furthermore, its photocatalytic efficiency can be improved by combining it with metal nanomaterials exhibiting surface plasmon resonance (SPR). When SPR acts on nanostructures or nanoparticles, a phenomenon called localized surface plasmon resonance is generated. The localized spatial field strength of the Resonance (LSPR) is such that when the size of noble metal materials (such as Au, Ag, Cu) is smaller than the wavelength of incident light, electrons form resonance under the drive of the external electric field, resulting in strong absorption and scattering. This phenomenon not only has a profound impact on the properties of nanoparticles themselves, but also provides great potential for their application in optoelectronics, sensing technology and catalysis.

[0034] This invention uses a wide bandgap material, TiO2 nanotube array, as a substrate, combining it with the transition metal oxide MnO2. MnO2, as a p-type semiconductor, possesses strong oxidizing properties, a narrow bandgap, and electrochemical activity due to its complex and varied crystal structure. When combined, the complementary nature of their band structures helps form a wider effective bandgap, influencing carrier separation and migration, and enhancing the material's photocatalytic performance. The composite structure MnO2 / TiO2 can selectively recognize HCHO gas at room temperature. To further improve detection performance, silver nanoparticles are introduced onto the surface of the original structure to enhance light absorption and promote carrier transfer. The silver nanoparticle surface can transfer carriers to oxygen molecules, forming reactive oxygen species, significantly improving the material's gas catalytic activity at room temperature. To improve the stability of the detection system and prevent oxidation of the silver nanoparticle surface by air, this invention forms a silver sulfide shell by sulfiding the surface of the silver nanoparticles, improving the repeatability and long-term stability of HCHO detection.

[0035] The terminal equipment includes: resistor 105, signal amplification unit 106, microcontroller 107, crystal oscillator circuit 108, power supply 109, and LED indicator 110. The connection between resistor 105, signal amplification unit 106, microcontroller 107, crystal oscillator circuit 108, power supply 109, and LED indicator 110 is realized through the circuit on the flexible printed circuit board. The positive and negative terminals of power supply 109 are connected to the circuit respectively. Power supply 109 is a 3.3V-5V button battery, which provides current to all circuits on the flexible printed circuit board. The LED indicator is a strobe light.

[0036] The wristband includes: a buckle 201, a locking ring 202, and a locking hole 203. The buckle 201 passes through the locking ring 202 and engages with the locking hole 203 to ensure the wristband is securely worn. The wristband is detachable and replaceable. The wristband is made of silicone or leather.

[0037] Operating principle:

[0038] This invention relates to a wearable wristband for formaldehyde gas detection. The power-on process provides current to the entire circuit. The crystal oscillator circuit, a capacitor-based oscillation loop, provides a clock signal to the microcontroller, driving it to perform corresponding logic operations. When formaldehyde gas enters the semiconductor sensor chip in the flexible sensing area, the composite structure of MnO2 and TiO2 in the semiconductor sensor chip forms a wider effective bandgap, thus affecting carrier separation and migration, improving the photocatalytic performance of the material. Simultaneously, the introduction of silver nanoparticles enhances light absorption and promotes carrier transfer. The sulfidation of the silver nanoparticle surface forms a silver sulfide shell, further improving the repeatability and long-term stability of HCHO detection. The resistance signal generated by the flow carrier transfer is transmitted to the terminal block through the copper foil circuit. The terminal block connects to the circuit on the flexible printed circuit board, which in turn transmits the resistance signal to the resistor. The resistor's function is to adjust the current to a suitable level. Then, the signal passes through the signal amplification unit, which amplifies the weak signal received from the resistor and transmits it to the microcontroller. This ensures that the microcontroller can accurately read the amplified signal for data processing and simultaneously control the blinking of the LED strobe light. This achieves real-time detection of HCHO gas. When the HCHO gas disappears, the crystal oscillator circuit resets the microcontroller, causing the LED to stop blinking. Therefore, long-term stable and repeated detection of HCHO gas is possible.

Claims

1. A wearable wristband for formaldehyde gas detection, characterized in that, include: A flexible formaldehyde gas sensor and a wristband, with the wristband connecting both ends of the flexible formaldehyde gas sensor. The flexible formaldehyde gas sensor includes: a flexible sensing area, a flexible printed circuit board, a terminal device, and a substrate layer; the flexible printed circuit board covers the substrate layer, and the flexible sensing area and the terminal device are located on the flexible printed circuit board. The flexible sensing area includes: a semiconductor sensing chip, a flexible electrode, a copper foil circuit, and a terminal block. The semiconductor sensing chip is located on the flexible electrode and partially overlaps and contacts the flexible electrode. One end of the copper foil circuit is connected to the flexible electrode, and the other end is connected to the terminal block. The terminal block is connected to the circuit on the flexible printed circuit board. The terminal device includes: a resistor, a signal amplification unit, a microcontroller, a crystal oscillator circuit, a power supply, and an LED indicator. The resistor, signal amplification unit, microcontroller, crystal oscillator circuit, power supply, and LED indicator are connected through circuits on a flexible printed circuit board. The positive and negative terminals of the power supply are respectively connected to the circuits on the flexible printed circuit board. The power supply provides current to all circuits on the flexible printed circuit board.

2. A wearable wristband for formaldehyde gas detection as described in claim 1, characterized in that, The substrate layer is flexible polydimethylsiloxane.

3. A wearable bracelet for formaldehyde gas detection as described in claim 1, characterized in that, In the flexible sensing area, there is one circular semiconductor sensing chip; two rhomboid flexible electrodes; and two terminals. The semiconductor sensing chip is located between the two flexible electrodes and above one corner of the rhomboid shape.

4. A wearable wristband for formaldehyde gas detection as described in claim 1, characterized in that, The semiconductor sensing chip in the flexible sensing area is a composite structure formed by combining an N-type semiconductor with a P-type semiconductor, and has a silver sulfide shell on its surface.

5. A wearable bracelet for formaldehyde gas detection as described in claim 4, characterized in that, The N-type semiconductor is a TiO2 nanotube array, and the P-type semiconductor is a transition metal oxide MnO2.

6. A wearable bracelet for formaldehyde gas detection as described in claim 1, characterized in that, The terminals of the flexible sensing area are connected to the circuitry on the flexible printed circuit board via wires or conductive adhesive.

7. A wearable bracelet for formaldehyde gas detection as described in claim 1, characterized in that, The terminal device contains two resistors; the LED indicator is a strobe light.

8. A wearable bracelet for formaldehyde gas detection as described in claim 1, characterized in that, The power source for the terminal device is a 3.3V-5V button battery.

9. A wearable bracelet for formaldehyde gas detection as described in claim 1, characterized in that, The wristband includes a buckle, a locking ring, and a locking hole. The buckle passes through the locking ring and engages with the locking hole. The wristband is detachable and replaceable.

10. A wearable bracelet for formaldehyde gas detection as described in claim 1, characterized in that, The wristband is made of silicone or leather.

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