Diamond sensors for temperature and radiation measurement and helmet for real-time temperature and radiation detection

Abstract

Diamond sensors for temperature and radiation measurement and helmet for real-time temperature and radiation detection The disclosure relates to a manufacturing process of temperature sensors with detection properties through thermal conduction and electromagnetic radiation. These temperature sensors are NTC (negative temperature coefficient) thermistors that are based on diamond films on flat semiconductor and ceramic substrates. These sensors comprise a diamond surface that is sensitive to temperature and radiation, on one of the substrate surfaces, whether or not protected by a non-temperature-sensitive diamond surface and metal carbide ohmic contacts on the other surface of the substrate. The disclosure also relates to personal protective equipment (PPE) comprising the temperature and infrared radiation detection system for integration into helmets with sensors with high durability and small size, aimed at preventing injuries to professionals from exposure to extreme conditions. The sensors comprising this detection system consist of a layer of polycrystalline boron-doped diamond overlaid by a layer of non-boron-doped polycrystalline diamond.

Description

[0001] DESCRIPTION

[0002] Diamond sensors for temperature and radiation measurement and helmet for real-time temperature and radiation detection

[0003] Technical domain of the invention

[0004] The disclosure concerns the creation of diamond bifunctional temperature sensors, capable of capable of simultaneous contact measurement of temperature, and non-contact measurement of radiation, with high sensitivity in the infrared spectrum. These sensors can be used to assess the temperature of any solid, liquid or gas material or any electromechanical device through the well-known processes of heat transfer: conduction, convection, and radiation. Its small size, its low response time to temperature variations created by the different heat transfer processes, make these sensors the ideal solution in numerous applications. The present invention also refers to personal protective equipment (PPE) comprising said system for detecting temperature and infrared radiation for integration into, specifically helmets with sensors with high durability and small size, in order to prevent injuries to professionals caused by exposure to extreme conditions. The sensors that make up this detection system consist of a layer of polycrystalline boron-doped diamond overlaid by a layer of non-boron-doped polycrystalline diamond.

[0005] Summary of the invention

[0006] One of the goals of the present disclosure is a manufacturing process of temperature sensors with detection properties through thermal conduction and electromagnetic radiation. These temperature sensors are NTC thermistors (Negative Temperature Coefficient) based on diamond films on flat semiconductor and ceramic substrates. These sensors comprise a diamond surface sensitive to temperature on one of the substrate surfaces, protected or not by a diamond surface not sensitive to temperature, and also metallic carbide ohmic contacts on the other surface of the substrate. The described process has the advantage of controlling the thermoelectric response of the sensors over a wide temperature range. In this way, it is possible to produce sensors suitable for a huge variety of applications (higher / lower temperatures, faster / slower response times, higher electrical resistance, and greater stability). Another advantage of the process is the use of a single deposition technique to produce both the temperature-sensitive diamond surface and the ohmic contacts, compared to current manufacturing processes. The innovative diamond sensors are versatile for temperature measurement, suitable for applications requiring thermal contact or where contact is impractical. Their robust diamond coatings offer exceptional mechanical and chemical resilience, ensuring reliable performance in extreme conditions, including high and cryogenic temperatures, and environments with elevated ionizing radiation levels. Particularly in delicate fields like medicine and biology, these biocompatible and bioinert diamond sensors seamlessly integrate into devices interfacing with tissues and biological solutions, showcasing their adaptability and reliability across diverse settings.

[0007] Background of the Invention

[0008] Negative Temperature Coefficient (NTC) thermistors are thermally sensitive semiconductors that display a decrease in resistance with an increase in temperature. These devices are widely used for temperature measurements and constitute one of the most accurate types of temperature sensors, featuring rapid response times to small temperature variations. The temperature-sensitive element of an NTC thermistor is generally a sintered semiconductor material, usually composed of a mixture of polycrystalline ceramic oxides (the starting materials are different metal oxides, such as manganese, iron, cobalt, nickel, copper and zinc, to which other chemically stable oxides can be added). However, for these materials, there is a strong dependence of the resistance-temperature characteristics on the composition and microstructure of the mixture. Consequently, for these materials, strict control of chemical homogeneity and processing parameters is necessary to achieve reproducibility of specific desired characteristics. Additionally, NTC thermistors can achieve higher accuracy within a limited temperature range (typically between -90°C to 130°C or, in some special cases, up to 300°C). Thermistors are also fragile elements and cannot be placed in hostile environments. Furthermore, due to their metal content, they cannot be used in contact with biological substances. Finally, these thermistors are not chemically resistant, which limits their use in chemically aggressive environments. As a result, in many applications, thermistors are placed inside metal tubes to protect them from the environment. However, this procedure affects the sensor's performance as it interferes with the sensor's response time (due to the presence of metal between the environment and the thermally sensitive zone). Therefore, there is a need for new thermistors that can overcome some of these limitations.

[0009] Semiconductor materials with high bandwidth - wide bandgap materials - such as SiC and diamond, have been developed and incorporated into the manufacturing processes of high-temperature sensors. In particular, crystalline, polycrystalline, multilayered, doped and undoped SiC, CVD diamond doped with boron, diamond and Si, have been investigated for applications in thermistors, achieving improved stability and reproducibility of these devices. Thermistors exhibit a large variation in their electrical resistance in response to a small temperature change. Normally, for NTC thermistors, this resistance change follows the Steinhart-Hart polynomial equation of degree 3: 1 / T = A + B[ln(R)] + C[ln(R)]2 + D[ln(R)]3, where R is the electrical resistance, T is the temperature, and A, B, C, and D, are the Steinhart-Hart parameters. An important characteristic of a thermistor is its sensitivity, which is generally characterized by the constant f> (K), defined by f>=Ln(R1 / R2) / (1 / T1-1 / T2) or by the Temperature Coefficient of Resistance TCR (ppm / K), defined by TCR=(R2-R1) / R1(T2-T1), for a specific temperature range - the larger the value of p or TCR, the greater its thermal sensitivity. The typical values of f> for conventional metal oxide thermistors range from 2000-4000K over the temperature range of 300-673K, while for CVD diamond thermistors, f> values in the range of 350-5500K have been reported. However, it has been observed that the highest sensitivity is achieved with low levels of boron doping, where the corresponding resistance is too high for many applications. Therefore, any synthesis process for diamondbased thermistors must allow for precise control of the boron doping level. This is extremely important to achieve a balance between high sensitivity and low electrical resistance of the thermistor.

[0010] To obtain devices that use diamond surfaces with electrical conductivity, electrical contacts are necessary between the diamond surface and other parts of the device circuit. In most cases, it is preferable for these contacts to be ohmic, as they ensure linear voltage-current characteristics and have low electrical losses. Furthermore, for applications requiring high temperatures and high mechanical stresses, these contacts must maintain their structural and electronic stability, as well as good adhesion to the diamond surface to prevent delamination. A wide range of metals have been used for the fabrication of contacts on conductive diamond films. The behavior of these contacts is complex and appears to strongly depend on the termination of the diamond surface, which, in turn, is determined by the surface pre-treatment, the quality of the diamond, and the growth technique used. The surface termination of diamond films can be modified, allowing for the obtainment of metallic contacts with rectifying and ohmic characteristics. Therefore, the development of high-quality ohmic contacts on diamond is a complex task for the production of electronic devices containing diamond. These contacts are particularly difficult to fabricate on moderately doped surfaces, due to the large difference in work function between the metal and the semiconductor diamond. As a result, rectifying contacts (Schottky) are normally obtained.

[0011] Currently, there are four main approaches for forming low electrical resistance ohmic contacts in diamond. One of these approaches is based on doping diamond using the ion implantation process with boron, or during the CVD process with boron doping on the diamond surface area where the metallic contact is intended to be formed. A second approach involves damaging the CVD diamond surface by disrupting the sp3 carbon bonding in a graphite layer. This can be achieved through ion implantation with low-energy ions. In the third approach, ohmic contacts are obtained after the vapor phase deposition of carbide-forming metals, for example, titanium followed by a heat treatment. With this method, ohmic contacts with multilayer structures such as Ti / Pt / Au can be achieved. Despite these contacts tending to adhere well to the diamond surface, their electrical performance is still relatively weak (unstable signals and high electrical resistance). Finally, a fourth approach uses a diamond-like carbon (DLC) layer deposited between the diamond layer and the metal layer. In this way, a better bonding of the contact to the diamond surface is obtained, thus increasing the durability of the metallic contacts.

[0012] The US patent US4,806,900 describes the method of producing a thermistor using a thin film of semiconductor CVD diamond as the temperature-sensitive element. In this report, a temperature-sensitive diamond layer is preferably deposited on a single-crystal diamond substrate, characterized by low specific heat (0.5 J / GK) and high thermal conductivity (20 W / cm.K). Pure metals (such as Ti, Mo, W, Ni), polycrystalline Si, as well as SiC, Si3N4, TiC, AI2O3, AIN, and NbC ceramics have also been used as substrates for the growth of thermally sensitive diamond films. On the other hand, boron, aluminum, sulfur, phosphorus, arsenic, chlorine, and antimony have been used as dopant elements by adding gaseous compounds to the methane and hydrogen gas mixture. In the formation of ohmic electrodes on the surface of the doped diamond layer, Ti, Mo, Ta, Ni, Al, and Au layers are deposited by vacuum evaporation, while TIN, TiC, and TaN layers are formed by reactive evaporation. The W layer is formed by sputtering. Finally, a protective layer of SiO2 or AI2O3 is deposited on the semiconductor diamond layer and electrodes using a sputtering technique. Nevertheless, there are some disadvantages to this method: 1 - its complexity, due to the need for different deposition techniques (one for the semiconductor diamond film, one for the ohmic electrodes, and another for the protective coating); 2 - since the ohmic electrodes are formed on the surface of the thermally sensitive diamond, it is always necessary to deposit a protective layer over the electrodes and the semiconductor diamond surface to prevent electrical interaction with conductive liquids, gases, and solids.

[0013] The US patent US5,066,938 describes the invention of CVD diamond thermistors that can simultaneously be formed on a substrate by selective deposition and photolithography. An insulating layer of CVD diamond is initially formed on a sintered ceramic (Si3N4) or metallic substrate before the semiconductor diamond layer by applying the selective deposition method on the diamond layer in a desired pattern. Metal electrodes are then formed on the semiconductor diamond layer by photolithography. Finally, the diamond film is coated with an oxidation-resistant protective film to be used in environments that can deteriorate the semiconductor diamond layer through oxidation.

[0014] A CVD diamond thermistor, comprising Ti / Au electrical contacts, was fabricated on sintered Si3N4 substrates. In this report, Ti produces an ohmic contact with boron-doped CVD diamond. However, a protective Au layer is required to prevent oxidation of the Ti layer. Furthermore, the described diamond thermistor does not report response to radiation. The US patent US5,089,802 describes the invention of a diamond thermistor in which parts of the temperature-sensitive diamond surface are doped by ion implantation to form ohmic electrical contacts. The film is then subjected to laser annealing to recover the damage caused by ion implantation. Two electrodes are deposited on the p-type doped regions by vapor phase evaporation or sputtering. The electrodes are formed by a double film where the lower layer is a titanium or tungsten film and the upper layer is aluminum to which electrical wires can be connected. Finally, a Si3N4 film is deposited over the entire surface of the structure to passivate the surface, providing anti -reflective properties and high oxidation resistance. However, this method of producing diamond thermistors requires the consecutive application of several complex and specific techniques: a CVD process for depositing thin diamond films, ion implantation for ohmic contacts, laser annealing, and sputtering. Consequently, the production cost of these diamond thermistors is quite high, and therefore not the best process for industrial application. Furthermore, the described diamond thermistor does not report response to radiation.

[0015] The US patent US5, 317,302 describes a method for producing a diamond thermistor consisting of a CVD diamond film sensitive to temperature, with high f> and low contact resistance at its terminals. In comparison to the US patent US5,089,802, this invention eliminates the need for ion implantation and subsequent laser annealing to create ohmic contact regions. These contact regions are formed by depositing a doped diamond film (p-type or n-type semiconductor film) on a temperature-sensitive diamond film (intrinsic semiconductor with high f> coefficient). This doped diamond film is then removed using a mask, leaving parts corresponding to the contact regions where the electrodes are deposited. The technical solution used in the manufacture of the ohmic contacts in these sensors differs from these works because, firstly, it uses only a single technique (chemical vapor deposition using a hot filament) for depositing both the ohmic contacts and the temperature-sensitive diamond surface. Secondly, the ohmic contacts are formed on the substrate face opposite to the face containing the thermally sensitive diamond surface. Furthermore, the described diamond thermistor does not report response to radiation.

[0016] Based on this, it can be inferred that the implementation of this technology can be expanded to all firefighting forces globally, aiming for a safer and more effective work environment for all professionals involved in firefighting activities, including rural fires and different types of equipment. The technology consists of incorporating a device capable of detecting high temperatures, infrared radiation, and producing audible and / or visual alerts in their respective helmets. This device aims to improve the safety of the PPE used by these professionals, as they reduce some sensitivity to external stimuli, particularly temperature. This technology is composed of a temperature sensor based on boron-doped diamond, a material with excellent mechanical, thermal, and chemical properties that surpass materials for temperature monitoring manufactured to date, making it suitable for use in extreme environments. The sensors are compact and have low energy consumption, allowing easy integration as a mobile device attached to a sound or visual alert system, without compromising operational mobility.

[0017] Recently, the sensors' sensitivity to infrared radiation has also been verified, providing dual signal detection functionality, which could be an asset in the process of locating fire sources or as redundancy to the temperature alert system if the operator gets too close to the burning material, providing competitiveness compared to existing sensors on the market that do not possess both characteristics. The diamond sensor is produced using the Hot-Filament Chemical Vapor Deposition technique, according to an innovative methodology developed and optimized at the University of Aveiro under the conditions stipulated in Table 1. Its composition involves depositing a polycrystalline layer of boron-doped diamond, sensitive to temperature, followed by a protective polycrystalline layer of undoped diamond on a variety of substrates such as Si (Silicon), C (Diamond), SiC (Silicon Carbide), C (Glassy Carbon), SiO2 (Quartz), Ti (Titanium), W (Tungsten), AIN (Aluminum Nitride), GaN (Gallium Nitride), AI2O3 (Aluminum Oxide), Stainless Steel, Mo (Molybdenum), Cu (Copper), Pt (Platinum). This sensor will be associated with an electronic device and implemented in helmets, adding value to the final product. The activation of the alarm and the constitution of the circuit used are directly related to the resistance of the boron-doped polycrystalline diamond films used for this application.

[0018] The use of this device can allow rapid, real-time detection of the ambient temperature and / or body temperature to which the professional is exposed, thus avoiding possible injuries or deaths. Boron-doped diamond sensors are sensitive to infrared radiation, characteristic of a photoconductor, which can exhibit a reduction of up to 70% in resistance when exposed to a 100 W infrared radiation lamp, as shown in Figure 7. The described sensors have a linear measurement range of temperature between 25-100°C as described in Figure 8. In addition to being resistant to high temperatures, this sensor has the ability to withstand negative temperatures, particularly by direct immersion in liquid nitrogen, without compromising its operation, as demonstrated in Figure 9. When subjected to a continuous flow of air at 350°C for 5 minutes, the sensors show no changes in their initial resistance. The same occurs with exposure to 600°C for 10 seconds, although at this temperature, there may be changes in the boron-doped diamond surface if it is not properly protected by the undoped boron diamond layer.

[0019] The article "Boron Doped Diamond for Real-Time Wireless Cutting Temperature Monitoring of Diamond Coated Carbide Tools" discloses the infrared radiation detection capability of boron-doped diamond sensors in drilling tools and their correlation with potential differences resulting from changes in the electrical resistance of this semiconductor, characterized as a thermistor. The technology associated with this article involves the use of photodiodes for information transmission between the sensor and a fixed data acquisition system. However, the present invention uses the potential difference variation so that a microcontroller integrated into a compact circuit, capable of being implemented in helmets, activates an audible and / or visual alert to warn the user. Additionally, the new technology will rely not only on the exclusive detection of IR radiation but also on the multi-sensor detection of radiation and temperature, providing an advantage in its use in confined spaces, particularly in structural firefighting, where the necessary conditions prevail to activate the alert mechanism.

[0020] The article "Tough negative temperature coefficient diamond thermistors comprising tungsten carbide ohmic contacts" discloses the use of boron-doped diamond as a thermistor associated with a specialized technique for creating tungsten carbide ohmic contacts. The document characterizes two boron-doped diamond thermistors with well-defined and very specific deposition characteristics that will not be used for the innovative technology described in the present document. However, the response of the sensors described in the article does not apply to the present technology because each deposition condition originates polycrystalline films with unique characteristics of morphology, composition, thickness, and electrical resistance, which can be adjusted according to the intended application. The present technology also differs from the one mentioned by eliminating the edge conduction effect associated with hot-filament chemical vapor deposition (HFCVD) deposition by delimiting the use of the inner zone of the diamond surface through laser cutting after deposition to obtain sensors with enhanced quality and reduced dimensions.

[0021] Regarding the "Burn Saver" technology, the sensors used are not made of boron-doped diamond and do not have competitive characteristics of durability and resistance to high temperatures compared to the technology present in the document. Regarding thermal imaging cameras, there are no records to date of using boron-doped diamond sensors for thermal image acquisition, and the technology involved is more complex and economically unfeasible for the needs that boron- doped diamond sensors can address.

[0022] Patent US20070177651 A1 describes a portable device for continuous monitoring of body temperature for exclusive use in helmets or head equipment. The device uses a thermistor to record the user's body temperature and displays the results on a monitor. It can also be programmed to trigger a sound or visual alarm in case of dangerous temperature. On the other hand, boron-doped diamond is a material with exceptional thermal and electrical properties that allow integration into extreme environments, which is not described by the presented patent.

[0023] In terms of performance, the continuous body temperature monitoring device described in the patent has the primary objective of providing an early warning of dangerous changes in the user's body temperature, and not the surrounding environment.

[0024] General Description

[0025] The present invention relates to a new type of diamond temperature sensor (thermistor) and its manufacturing process. These new diamond sensors were obtained using the technique of hot filament chemical vapor deposition (HFCVD). They consist of a p-type semiconductor CVD diamond film, nanocrystalline or microcrystalline, with a thickness ranging from 1-10 pm or more, grown on the surface of an intrinsic or doped single-crystal silicon flat substrate. Other semiconductors such as Ge and GaN, and ultra-hard ceramics like dense silicon nitride (Si3N4), can also be used as substrates, depending on the final application of the sensor. After the substrate surface is scratched with diamond particles (by ultrasonic or abrasive polishing) of different sizes, the substrates are cut to the desired dimensions (from a few mm2 to several hundred mm2) mechanically or by laser. The p-type semiconductor diamond temperaturesensitive layer is obtained after growth for one to four hours, a duration depending on the desired final thickness of the thermally sensitive film. Following the growth of the doped diamond layer, ohmic contacts are made on the opposite side of the substrate. To achieve this, the substrate is flipped and placed back in the HFCVD system with the bottom surface exposed to tungsten filaments. The tungsten filaments are then evaporated in a primary vacuum (>5 Pa) for a few minutes at a fixed filament temperature. This process deposits a tungsten layer not only on the bottom surface of the Si3N4 substrate but also on the side faces containing the boron-doped diamond film. This tungsten layer is subsequently carburized into WC phase using hydrogen and methane for an hour at a substrate temperature of >600°C. Longer times and higher temperatures have similar effects on the electrical conductivity of the WC film.

[0026] To protect the thermally sensitive diamond layer from environmental interaction, a final step in the CVD process is implemented. In this step, a non-doped CVD diamond layer is grown on the doped diamond layer (1-3 microns thick). For applications above 600°C, the non-doped CVD diamond layer can be replaced with SiO2, Si3N4, or AI2O3 obtained by sputtering.

[0027] The firefighting of structural fires is an extremely risky activity that demands a high level of technical expertise and physical preparedness from the professionals involved. It is common, during search and rescue operations in buildings or industries, to encounter an accumulation of gases with extreme temperatures in confined spaces, further increasing the risk for firefighters. With the aim of ensuring the safety of the professionals involved in these operations, the use of protective devices is of utmost importance. In this sense, another goal of the present disclosure is the incorporation of a small device in personal protective equipment ( PPE), particularly in helmets, that assists in detecting radiation and high temperatures, can be an effective solution to minimize the risks inherent in structural firefighting work. In Portugal, the presence of around 465 fire departments highlights the significant commitment to firefighting, with a collective force of approximately 26,000 dedicated firefighters. Comparatively, the European landscape in 2022 had a substantial number of about 360,000 professional firefighters, encompassing an estimated total of more than 1.4 million individuals engaged in firefighting as volunteers or professionals. In the United States, there were 324,149 professional firefighters, emphasizing the importance of regularly renewing their protective gear to ensure their safety and effectiveness in emergency response situations. This global distribution of firefighters underscores the critical role they play in safeguarding communities and responding to emergencies worldwide.

[0028] In an embodiment the present disclosure pertains to a sensor for temperature and radiation measuring, obtained by hot filament chemical vapor deposition (HFCVD), the sensor comprising a diamond surface, which comprises a nanocrystalline or a microcrystalline p-type semiconductor CVD diamond film, the film being on one side of the surface of an intrinsic or doped single-crystal silicon, Ge and GaN or ultra-hard ceramics like dense silicon nitride (Si3N4), AIN, SiC. B4C, BN or WC flat substrate, and comprising ohmic contacts on the opposite side of said substrate.

[0029] In a further embodiment the present disclosure relates to a sensor wherein the substrate comprises Vickers hardness values ranging from 12-30GPa and Young's Modulus between 200-500GPa.

[0030] In a further embodiment the present disclosure relates to a sensor further comprising a polycrystalline boron-doped diamond, optionally overlaid by a layer of non-boron-doped polycrystalline diamond.

[0031] In a further embodiment the present disclosure relates to a sensor wherein the diamond surface comprises a surface roughness from 0,012Dm to 2pm with a microstructure variation between nanocrystalline and microcrystalline.

[0032] In a further embodiment the present disclosure relates to a sensor wherein the diamond surface presents a thermal conductivity from 15-25 Wcm-1 K-1.

[0033] In a particular embodiment, the present disclosure relates to a method for obtaining the sensor of any of the previous embodiments, comprising the steps: i) placing the substrate inside a hot filament chemical vapor deposition (HFCVD) system on a metal support located at a distance not greater than the distance between adjacent filaments; ii) a boron-doped diamond layer is grown on the substrate at a methane / hydrogen ratio of 0.5-10%, boron flux of 0- 5pl / min, argon flux of 0-50ml / min, pressure of 15-150mbar, substrate temperature of 600-900°C, filament temperature of 2000-2500°C, until an average thickness of 1-10 pm is obtained;

[0034] Hi) turning the substrate over and placing it back into the HFCVD system with the uncoated surface facing tungsten filaments; iv) evaporating the tungsten filaments in primary vacuum at >5Pa for 2-4 minutes at a filament temperature between 1500-1900°C; v) adding hydrogen at a constant flow of 100 ml / min, at a total pressure of 5 kPa, with the filaments at 2100°C, for 2-3 minutes; vi) adding a carbon-containing gas to the hydrogen flow for 4-5 minutes at 4 ml / min, while the substrate is kept at 600- 700 °C, resulting in a tungsten carbide layer, where the tungsten carbide layer is transformed into the WC phase with hydrogen and methane gases, for one hour at a substrate temperature >600°C; vii) mechanically removing the tungsten carbide layer from the two lateral and opposite surfaces of the substrate, using an abrasive disc; viii) adding an insulating protective layer to the boron-doped diamond.

[0035] In a particular embodiment, the present disclosure relates to a method wherein the substrate surface is scratched with diamond particles by ultrasonic or abrasive polishing of different sizes.

[0036] In a particular embodiment, the present disclosure relates to a method wherein substrates are cut to the desired dimensions, mechanically or by laser.

[0037] In a particular embodiment, the present disclosure relates to a method wherein substrates are subjected to a treatment comprising tetrafluoromethane plasma.

[0038] In a particular embodiment, the present disclosure relates to a method wherein the substrate undergoes abrasion on a soft cloth with 0.5-1 pm diamond powder or is placed in an ultrasonic bath in a suspension of 0.5-1 pm diamond powder in 99.9% pure ethanol or other suspensions with diamond particle sizes ranging from 0.5pm to 60pm.

[0039] In a particular embodiment, the present disclosure relates to a method wherein loose diamond particles are removed from the substrates with acetone in an ultrasonic bath for 10 minutes and subsequently in pure ethanol for 10 minutes. In a particular embodiment, the present disclosure relates to a method wherein the boron source is boron oxide dissolved in ethanol at a concentration from 100 ppm to 15000, preferably 10000 ppm, to obtain a boron-containing solution which is placed in a reservoir pressurized, wherein the amount of boron-containing solution and ethanol supplied is controlled through a flow meter calibrated for the boron-containing solution solution.

[0040] In a particular embodiment, the present disclosure relates to a method wherein the doped diamond layer is an electrical insulator, preferably a non-doped polycrystalline diamond layer, in particular a Si3N4, or SiO2 layer, preferably an AI2O3 layer, by cathodic spraying.

[0041] In a particular embodiment, the present disclosure relates to a method further comprising the step of forming a notch (4) in the deposited tungsten carbide layer, connecting the two faces of the substrate, using a diamond cutting disk or wire and subsequently, optionally, a step of laser cutting.

[0042] In a further embodiment, the present disclosure relates to the use of the sensor of the present disclosure for monitoring the ambient temperature and radiation in personal protective equipment.

[0043] In a further embodiment, the present disclosure relates to the use of the sensor of the present disclosure for detection and measurement of temperature and radiation in combustion and jet engines for the automotive and aerospace industry, natural gas exploration lasers, drilling, fuel cells or in deep ocean.

[0044] In a further embodiment, the present disclosure relates to the use of the sensor of the present disclosure in platforms for immobilization of biomolecules, detection of chemical reactions in processes where heat exchange occurs, in chemical and biological environments or in dentistry.

[0045] In a further embodiment, the present disclosure relates to the use of the sensor of the present disclosure in nuclear reactors and in equipment for the diagnosis and treatment of cancer with highly ionizing radiation.

[0046] In a further embodiment, the present disclosure also relates to personal protective equipment comprising the sensor herein disclosed. In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation comprising a sensor according to the present disclosure, an electronic comparator amplifier circuit and a sound and visual alarm circuit, wherein all of said components are deployed in the upper area of the helmet.

[0047] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation wherein the sensor comprises a boron-doped diamond layer and a protective layer of undoped boron diamond.

[0048] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation wherein the ceramic substrate is used, preferably silicon nitride (Si3N4), or a semiconductor substrate, preferably monocrystalline silicon.

[0049] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation further comprising electronic comparator amplifier circuit comprising a microprocessor for data processing, the electronic comparator amplifier circuit preferably comprising 4 sensor connection inputs.

[0050] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation with maximum dimensions of 20x15 cm, excluding the length of the connector wires to the sensors.

[0051] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation further comprising four adjustable potentiometers, which are electrical resistances with values between 10- 200,0000.

[0052] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation further comprising an external battery optionally comprising a potential difference not exceeding 9V.

[0053] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation further comprising a sound and visual alarm circuit comprising an alarm component, optionally audible, and / or means for emitting a high-intensity sound or a visual signal, preferably by emitting a flashing light signal. In a particular embodiment the sound alarm emits a sound with intensity not less than 80 dB.

[0054] In a further embodiment, the present disclosure also relates to a helmet for real-time detection of temperature and radiation, wherein the activation of the alarm occurs when the temperature measured by the sensor reaches an adjustable reference value, which is optionally individually set for each potentiometer.

[0055] In a further embodiment, the present disclosure also relates to personal protective equipment comprising the helmet of any of the previous embodiments.

[0056] Description of the Figures

[0057] A detailed description accompanied by figures is now presented:

[0058] Figure 1a shows the positioning of the flat ceramic substrate Si3N4 (1) inside the HFCVD chamber, on the support (2), and under the filaments (3).

[0059] Figure 1b shows the positioning of the flat ceramic substrate Si3N4 (1) inside the HFCVD chamber, on the support (2), and under the filaments (3) separated by a metal or ceramic plate (4).

[0060] Figure 2 shows a cross-sectional view of a diamond film thermistor in a preferred embodiment according to the present application. A boron-doped diamond layer (1-2 pm thick) (2) is grown on the ceramic substrate (1). The tungsten- containing layer (3) is formed after the thermal evaporation of tungsten filaments. A notch (4) is created in this WC layer using a diamond-coated disk or wire. Electrical connection with wires (5) is then made to these contacts, and an electrical insulation layer (6) is deposited over the doped diamond layer.

[0061] Figure 3 shows the current-voltage characteristic curves of the thermistor at different temperatures. The tungsten carbide contacts exhibit ohmic behavior in the temperature range of 25-425°C.

[0062] Figure 4 shows a cross-sectional view of a diamond film thermistor in another preferred embodiment according to the present application. A boron-doped diamond layer (1-2 pm thick) (2) is grown on the ceramic substrate (1). The tungsten-containing layer (3) is formed after the thermal evaporation of tungsten filaments. A notch (4) is created in this WC layer using a diamond-coated disk or wire. Electrical connection with wires (5) is then made to these contacts, and an electrical insulation layer (6) is deposited over the doped diamond layer.

[0063] Figure 5 illustrates a graph showing how the TCR value and electrical resistance at room temperature vary according to the produced sensor. For this study, 16 different samples were produced.

[0064] Figure 6 illustrates the effect of different deposition parameters on the TCR value (in the range of 20-50°C) of each of the HFCVD parameters used. This analysis was conducted using the Taguchi method with a series of 16 samples produced with different HFCVD parameters. Higher TCR values are achieved for lower CH4 and Boron flows, the optimal Argon flow is 10 seem, and Ts is 800°C. Gas pressure does not seem to significantly influence the TCR value. Figure 7 demonstrates the linear behavior of the electrical resistance variation with temperature, for the range of 20- 100°C (in this case for sample L1 from Table 1). The advantage of these sensors compared to commercial thermistors is immediately apparent - the linearity is complete over a wide temperature range (20-100°C). In commercial sensors, the R(Q) behavior follows a 3rd-degree polynomial function.

[0065] Figure 8 shows the diversity of microstructures and surface morphologies of the thermally active diamond surface that can be obtained. The SEM images demonstrate that it is possible to produce thermally sensitive diamond surfaces by adjusting the HFCVD conditions to create coatings typically nanocrystalline (NCD) and microcrystalline (MCD).

[0066] Figure 9 illustrates the effect of infrared radiation on the electrical resistance value of the sensor. This graph presents results for three sensors where the Resistance value is measured with the sensors in the dark and when illuminated with infrared radiation from a 100W lamp at a distance of 20cm.

[0067] Figure 10 presents the graph showing the quantitative variation of the electrical resistance value of a diamond sensor when subjected to a rapid temperature change, from room temperature (25°C) to the temperature of liquid nitrogen (- 195.8°C), in less than 2 seconds.

[0068] Figure 11 presents the operating principle of boron-doped diamond as a semiconductor material through "hole currents" is represented.

[0069] Figures 12 and 13 are scanning electron microscopy images of a polycrystalline boron-doped diamond surface are shown.

[0070] Figure 14 is an example of the technology application in structural firefighting helmets, associated with a sound alarm system, is represented to demonstrate one of the most extreme usage scenarios for the sensors. A - diamond sensors possible location in the back of the helmet; B - prototype circuit board implemented in the helmet; C - diamond sensors possible location in the front of the helmet.

[0071] Figure 15 presents the simplified assembly of the boron-doped diamond and the contacts for integration into a circuit is represented. These should be applied to the entire edge of the sensor and should be in direct contact with the boron- doped diamond layer. Figure 16, an example of a circuit board with the capability to use 4 sensors simultaneously for activating a sound alarm system is represented.

[0072] Figure 17 presents a possible assembly of the boron-doped diamond sensor in a structural firefighting helmet.

[0073] Figure 18 presents the prototype circuit that controls the signal obtained by the boron-doped diamond sensor, triggering a sound alarm when a defined limit is exceeded.

[0074] Detailed Description of the Invention

[0075] Dense ceramic plates (> 99% of theoretical density) of silicon nitride (Si3N4) and monocrystalline silicon plates (for electronic grade, doped with Boron or undoped) with thicknesses <1 mm are used as substrates for depositing diamond film thermistors. On one hand, the silicon nitride substrate ensures excellent adhesion of the temperature-sensitive diamond layer and high fracture resistance for applications in harsh environments. These and other ceramic substrates (e.g., AIN, SiC, B4C, BN, WC) with high Vickers hardness values ranging from 12-30GPa and Young's Modulus between 200-500GPa can be used. On the other hand, the monocrystalline Si substrate ensures the essential semiconductor layer for forming the diamond surface with high infrared radiation detection. These substrates are commercially available. However, Si3N4 ceramic substrates can be produced by pressureless sintering using: (a) a mixture of a-Si3N4, Y2O3, and AI2O3 powders with weight proportions of 89.3 / 7.0 / 3.7%, for example, which is then mixed and milled in a ball mill with water or organic solvents, preferably isopropyl alcohol, dried, and sieved; (b) a commercial Si3N4 powder and sintering aids ready for sintering. The dried mixed powders are consolidated by isostatic pressing at 200-400 MPa, followed by sintering at 1700-1850°C for 1 -4h in a N2 atmosphere. The sintered bodies are then cut and ground with a diamond blade and wheel to achieve the desired dimensions (e.g., substrates of 3x3x1 or 10x10x1 mm3 can be obtained). The substrates are subsequently polished, preferably with diamond suspensions of 15 pm and 6 pm and colloidal silica (0.05 pm) for a final finish (Ra ~ 0.008 pm). The high adhesion of the diamond film to the ceramic substrate is ensured by applying a CF4 plasma on the polished substrates. In the case of Si substrates, the adhesion of the diamond coatings is always guaranteed by the similarity of the crystal structure of the two materials. Before growing the diamond layer, the substrates are placed in an ultrasonic bath in a suspension of 0.5-1 pm diamond powder in 99.9% pure ethanol or other suspensions with diamond particle sizes ranging from 0.5pm to. Ultrasonic abrasion can be replaced by a mechanical process where the substrate surface undergoes abrasion on a soft cloth with 0.5-1 pm diamond powder. The combination of both mechanical and ultrasonic processes produces surfaces that promote increased diamond nucleation rates. These high nucleation rates are crucial for achieving a continuous nanocrystalline diamond film, 1-2 pm thick in just 2-3 hours. Finally, loose diamond particles are removed from the substrates with acetone in an ultrasonic bath for 10 minutes and subsequently in pure ethanol for 10 minutes.

[0076] Figures 1a and 1b represent the two possible configurations of the ceramic substrate (1) placed inside the HFCVD system, on a rotating or stationary metal support (2), preferably made of molybdenum (since at temperatures below 900°C, Mo does not form carbides), below the metal filaments (3) and at a distance not greater than the distance between adjacent filaments. The rotation is fixed at 1-3 rpm, but other values can also be used. The rotation of the substrate ensures the uniformity of diamond growth across the entire substrate area and is maintained throughout the CVD process. Tungsten is the preferred metal used for the filaments. However, tantalum and rhenium can also be used. The substrate can be placed directly on the metal support, as shown in Figure 1a, or with a metal or ceramic plate between them (4) as shown in Figure 1b. This latter configuration ensures that the exposed part of the substrate's bottom surface is also coated with boron-doped diamond.

[0077] Figure 2 shows a cross-sectional view of a diamond film thermistor according to a first embodiment of the present application. On the treated surface of the ceramic substrate (1), a boron-doped semiconductor diamond layer (2) with an average thickness of 1-2 pm is grown using the growth conditions presented in Table 1. The boron source is boron oxide (B2O3) dissolved in ethanol at a concentration of 10000 ppm. Other concentrations between 100 ppm and 15000 ppm can also be used. This boron-containing solution is placed in a reservoir and pressurized with argon. The amount of the boron-containing solution and ethanol supplied to the deposition chamber is controlled through a flow meter calibrated for this solution. Argon is added to the deposition gases (hydrogen and methane). Argon is preferably used as it is non-flammable and inert. This inert gas helps in creating the necessary species for the growth of dielectric and semiconductor diamond surfaces. The substrates must be heated to the desired temperature before adding the synthesis gases for semiconductor diamond. This heating can be achieved through a graphite resistor located under the molybdenum metal support but with a ceramic material between them to prevent short circuits during the graphite resistor heating process. It is also crucial to start the boron flow immediately after or even during the tungsten filament carburization step. This ensures gas mixtures with high boron uniformity and that the substrate surface is also exposed to boron doping. This point is critical for producing a p-type semiconductor layer on the substrate. The p-type semiconductor layer of diamond has acceptor electronic levels with different energies in the diamond gap compared to the levels formed in the Si semiconductor substrate. This results in the creation of a p-p or n-p junction activated by infrared radiation.

[0078] After the growth step of the p-type semiconductor diamond film, the substrates are flipped and placed back in the CVD chamber with the uncoated surface facing the tungsten filaments. The tungsten filaments are then heated in primary vacuum (>5Pa) for 2-4 minutes to a filament temperature between 1500-2000°C. Other filament times and temperatures can also be used. The thickness of the tungsten-containing layer (3) will depend on the temperature, length, diameter, and number of filaments used, as well as the evaporation time. Deposition rates of tungsten between 40nm / min and 100nm / min can be achieved for filament temperatures of 1500°C and 1900°C, respectively. A publication shows that the thermally vaporized tungsten layer is predominantly composed of tungsten oxide (WO2). Since oxidized metal layers tend to form rectifying contacts on diamond, atomic hydrogen is needed to reduce tungsten oxide back to its metallic form. Therefore, hydrogen is added to the HFCVD system with a constant flow of 100ml / min, at a total pressure of 5 kPa, with the filaments at 2100°C, for about 2-3 minutes. Then, methane or other carbon-containing gases are added to the hydrogen flow for about 4-5 minutes at 4ml / min and at the same pressure and filament temperature, while the substrate is maintained at 600-700°C. These growth conditions allow hydrogen atoms and carbon species to diffuse into the tungsten layer and create a tungsten carbide coating. Ultimately, carbon radicals and atomic hydrogen can reach the boron-doped diamond film and induce diamond growth at the diamond-WC interface, resulting in a hybrid diamond-WC layer. This process ensures superior adhesion of the carbide layer to the boron- doped diamond layer. After the deposition of WC, the hybrid diamond-WC layer is mechanically removed from the two lateral and opposite surfaces of the ceramic substrate using a grinding wheel. A notch (4) is formed in the deposited tungsten carbide layer, connecting the two faces of the substrate, using a diamond cutting disk or wire. The final size of the samples and the formation of the notch (4) can also be achieved by laser cutting. This notch is essential to create two separate electrical contacts where electrical connections with wires (5) can be made. Electrical connections to the two created contacts can be achieved by soldering or mechanical contact. The graph in Figure 3 illustrates the VI characteristic curves of the diamond thermistors produced according to the present invention. It is concluded that the tungsten carbide contacts exhibit ohmic behavior in the temperature range of 25-425°C.

[0079] Finally, the use of this first embodiment for thermal contact with gaseous, liquid, and electrically conductive solids requires that the doped diamond layer be an electrical insulator. In the case of biological or chemically aggressive environments at temperatures <600°C, a non-doped polycrystalline diamond layer (6) obtained by the HFCVD process, or another CVD technique is chosen. For applications requiring temperatures above 600°C in oxidizing environments, a layer of Si3N4, AI2O3, or SiO2 is preferably used. This protective layer (6) can be deposited on the upper surface and / or sides of the thermally sensitive diamond layer, as indicated in Figure 4. These embodiments can be used in a variety of temperature measurement applications, with their selection only conditioned by very high temperature environments with oxygen.

[0080] The disclosed process can be used to produce a wide variety of diamond sensors, similar and in just a single CVD deposition, provided that the substrates are prepared in the same way and that the HFCVD substrate holder is kept rotating throughout the process. Additionally, the number of diamond sensors that can be obtained in a single run is only limited by the area of the HFCVD support. In Table 2, it is possible to see the HFCVD parameters used in the manufacture of some temperature sensors, as well as the respective calculated TCR value for the range 20-50°C. In an embodiment, typical TCR parameter values in the range of -200ppm / °C to -15000ppm / °C can be achieved. The f> parameter can vary between 100-3500K.

[0081] The graph in Figure 5 represents the TCR value and electrical resistance at room temperature as a function of the produced sensor. By adjusting the HFCVD parameters, sensors with electrical resistance values in the range of 10Q - 200kQ can be obtained. Correlating these values with the HFCVD parameters in Table 3, it is concluded that the desired TCR can be obtained by correctly adjusting the deposition parameters. In Figure 6, we see the effect on the TCR value of each of the HFCVD parameters used. Finally, the graph in Figure 7 confirms the linear behavior of the electrical resistance variation with temperature, for the range 20-120°C (in this case for sample L1 from Table 1).

[0082] The SEM images illustrated in Figure 8 show the diversity of microstructures and morphologies of the thermally active diamond surface that can be obtained. The surfaces of the obtained sensors have average roughness values between 0.012pm and 2pm, depending on the type of surface (nanocrystalline or microcrystalline).

[0083] The graph in Figure 9 presents the variations in the electrical resistance of three sensors when placed in the dark and illuminated with infrared radiation. This graph confirms the sensors' sensitivity to infrared radiation. A decrease in electrical resistance is observed, with relative variations of 50-70% in the electrical resistance value when the sensors are in the dark and then illuminated with infrared radiation.

[0084] The graphic in Figure 10 demonstrates the ability of the sensors to measure cryogenic temperatures, even functioning at temperatures as low as 77K (-195.8°C). This capability is reflected in the strong variation of electrical resistance. A significant increase in electrical resistance is observed, with relative variations of 50-300% when the sensor is at room temperature and comes into contact with liquid nitrogen.

[0085] The diamond surfaces also have the ability to quickly dissipate heat, as the thermal conductivity of this material is the highest known, with typical values of 15-25 Wcm-1 K-1. Since self-heating is a problem in commercial thermistors due to the passage of electric current, which causes heat dissipation by the Joule effect, these sensors are much less affected by self-heating when operated at lower potentials and, consequently, lower electric currents, combined with high thermal conductivity. The graph in Figure 3 confirms the need to use low operating potentials to obtain measurable currents in the sensor, a characteristic observed over a wide temperature range of operation.

[0086] Table 1. HFCVD growth conditions for the temperature-sensitive diamond layer and the electrically insulating diamond layer.

[0087] Table 2. Values of f> and TCR obtained for some temperature sensors, of boron-doped semiconductor diamond, obtained on undoped Si substrates. Table 3. HFCVD parameters used in the production of various boron-doped diamond temperature sensors on undoped Si substrates.

[0088] In Table 1 , the HFCVD deposition conditions for the temperature-sensitive diamond layer and the electrically insulating diamond layer are presented.

[0089] In Table 2, the values of f> and TCR obtained for some semiconductor boron-doped diamond temperature sensors on undoped Si substrates are presented.

[0090] In Table 3, the resistance values of the sensors corresponding to those shown in Figure 7, in direct contact with liquid nitrogen at a reference temperature of -196°C, are represented, proving their operability and applicability in various areas.

[0091] Several uses of the sensors of the present disclosure are envisaged. Flat diamond sensors are particularly suitable for application in extremely harsh environments where high and / or cryogenic temperatures dominate, in contact with chemically aggressive liquids and / or gases, in biological environments, as well as in applications subject to high mechanical stresses and ionizing radiation.

[0092] In an embodiment, the sensors of the present disclosure are used in exploration of the deep ocean where high pressures require sensors to withstand enormous mechanical loads and be corrosion -resistant.

[0093] In an embodiment, the sensors of the present disclosure are used in devices for monitoring physiological functions such as temperature and perspiration. These sensors can effectively detect sweating and simultaneously the body temperature of individuals with specific chronic and / or acute conditions.

[0094] In an embodiment, the sensors of the present disclosure are used in personal protective equipment (PPE) to monitor the ambient temperature where the professional is operating, alerting them through audible and visual alarms. These sensors can be used in equipment where temperature monitoring by contact is not possible (or undesirable) - gyroscopes, reaction wheels, combustion engines, etc. The biocompatibility of these sensors allows their use in processes for evaluating dental vitality by measuring the time required for a particular tooth to recover its temperature after being cooled.

[0095] In an embodiment, the sensors of the present disclosure are used in oil and natural gas exploration since diamond surfaces are extremely resistant to the erosive and abrasive wear characteristic of drilling methods.

[0096] In an embodiment, the sensors of the present disclosure are used in nuclear reactors and in equipment for the diagnosis and treatment of cancer with highly ionizing radiation.

[0097] Examples

[0098] Example 1 : Boron-doped diamond sensors are integrated into personal protective equipment (PPE), particularly helmets. They will function as temperature and infrared radiation detection sensors, characterized by a rapid response to temperature variations, high durability, and small size, in order to prevent injuries caused to professionals by exposure to extreme conditions.

[0099] Example 2: One of the most important applications of these sensors is their use in satellites. Satellites in Earth orbit are subjected to wide cyclic temperature fluctuations (between 300°C and -150°C). These temperature sensors can easily operate in this temperature range with high thermal stability. They are sensors with high resilience to the oxidative power characteristic of lower orbits and ionizing radiation. It also allows temperature detection by infrared radiation (without contact) since there is no thermal conduction or convection through the vacuum in space. The space industry can also benefit from these sensors during launch and landing stages, as these sensors have high mechanical resilience.

[0100] A set of two overlapped polycrystalline diamond films with NTC thermistor and photoconductor functions, where the lower film is composed of boron-doped diamond and the upper film is composed of undoped diamond, both with a thickness not exceeding 10 pm each and dimensions not exceeding 5x5 mm. The resistance of the films ranges from 10-200,000 Q. The deposition conditions are defined according to Table 1, allowing adaptation of the response according to the operational temperature, with the desired sensitivity / TCR. The diamond films for the described sensor are deposited on silicon (Si) and silicon nitride (Si3N4) substrates.

[0101] In an embodiment, the inclusion of the described sensor in a low-energy consumption, compact sound and / or visual alarm system, with the possibility of including multiple sensors simultaneously without compromising the individual operation of each for activation, is encompassed. The mentioned alarm system comprises an integrated microcontroller for comparing the resistance of each sensor with the respective adjusted trigger value. The microcontroller operates with a 4 MHz internal oscillator. As no conditional branching instruction is used, the normal instruction execution time (cycle) is 1 ps. The actual acquisition time is 200 ps. The system consists of a sensor that generates a voltage, sent to a comparator. This value is then applied to the input of an ADC module, which converts the analog signal to digital for processing by the microcontroller and conversion to temperature values. Based on the defined and programmed temperature value as a safety limit in the microcontroller, a sound or visual alarm will be activated whenever this value is equal to or exceeds the reference value. The sensors have photoconductivity characteristics that allow up to a 70% reduction in their initial resistance at room temperature when exposed to infrared radiation, as demonstrated in Figure 9. This factor will depend on the sensor conditions chosen according to the deposition conditions.

[0102] In an embodiment, the sensors operate between temperatures with an upper limit of 350°C indefinitely without compromising their integrity. The sensor also demonstrates the ability to withstand temperatures of -196°C by total immersion in liquid nitrogen without compromising operability. A linearity of material resistance in relation to temperature will be guaranteed within the range of 25-100°C.

[0103] The helmet for real-time temperature and radiation detection herein disclosed is an innovative device that offers an efficient and safe solution for monitoring these parameters in various situations.

[0104] The first essential component of the helmet is the boron-doped diamond sensor. This sensor is responsible for precise real-time temperature and radiation detection. It is highly sensitive and capable of providing accurate readings even in extreme conditions.

[0105] In an embodiment, the helmet has an electronic comparator amplifier circuit. This circuit processes the signals received by the sensor and converts them into understandable information. It plays a crucial role in detecting and interpreting the collected data.

[0106] In an embodiment, the helmet is also equipped with a sound and visual alarm circuit. This circuit is responsible for alerting the user if the temperature reaches a predefined reference value. The sound alarm emits a sound with intensity not less than 80 dB, while the visual alarm is presented in an embodiment as a flashing light signal.

[0107] All the above-mentioned components are deployed in the upper area of the helmet, ensuring its effectiveness and accuracy in temperature and radiation detection. The sensor itself has a boron-doped diamond layer and a protective layer of undoped boron diamond. These layers are synthesized using the hot-filament chemical vapor deposition process according to the present disclosure.

[0108] To ensure the durability and proper performance of the helmet, a ceramic substrate is used, preferably silicon nitride (Si3N4), or a semiconductor substrate, preferably monocrystalline silicon. In an embodiment, these substrates have hardness between 12-30 GPa and Young's modulus between 200-500 GPa.

[0109] The temperature sensor also exhibits linear behaviour of electrical resistance in relation to temperature, at least up to 120°C. It has optical sensitivity, mainly in the infrared region, allowing for the detection of relative variations of 50-70% in the electrical resistance value.

[0110] In an embodiment, the diamond sensor surface varies in terms of roughness, ranging from 0.012 pm to 2 pm, with a microstructure variation between nanocrystalline and microcrystalline. Additionally, diamond surfaces have thermal conductivity between 15-25 Wcm-’ K1.

[0111] In an embodiment the helmet is complemented by an electronic comparator amplifier circuit comprising a microprocessor for data processing. It also has compact dimensions, not exceeding, in an embodiment, 20x15 cm, excluding the length of the connector wires to the sensors.

[0112] In an embodiment, the electronic comparator amplifier circuit comprises four sensor connection inputs, allowing simultaneous monitoring of multiple points. Additionally, in an embodiment, it has four adjustable potentiometers, which are electrical resistances with values between 10-200,0000, used to calibrate and adjust the detection system.

[0113] The sound and visual alarm circuit has an alarm component, which can be audible, emitting a high-intensity sound, or visual, presenting a flashing light signal. The activation of this circuit occurs when the temperature reaches an adjustable reference value, which can be individually set for each potentiometer.

[0114] In an embodiment, the helmet is powered by an external battery, with a potential difference not exceeding 9V. This ensures that the helmet can be continuously used during the work or operation period.

[0115] The use of the helmet for real-time temperature and radiation detection is especially suitable for integration into personal protective equipment. Its advanced technology and precision in detection make it an essential tool to ensure the safety of users in environments where temperature and radiation are critical factors. Firefighters can use high- temperature detection technology in personal protective equipment to monitor ambient temperature during firefighting. This allows them to identify areas at risk of overheating and avoid potential injuries. In high-temperature industrial sectors such as foundries or steelworks, workers can use the technology in their PPE to detect and monitor the workplace temperature to prevent exposure to excessive temperatures and take appropriate safety measures. In construction work involving exposure to high temperatures, such as welding or furnace operation, workers can use high-temperature detection technology in their PPE to monitor their own body and / or external temperature to prevent heat exhaustion and heatstrokes. Workers in metallurgical factories or foundry industries can benefit from incorporating the technology into their PPE for detecting extreme temperatures in workplaces with heated metals, helping to prevent burns and other heat-related risks. In the petrochemical industry, where handling hazardous chemicals is common, high-temperature detection technology can be integrated into workers' PPE, allowing continuous monitoring of ambient temperature, avoiding exposure to extreme thermal conditions, and minimizing accident risks. Professionals working in cold storage rooms, refrigerated warehouses, or industrial refrigeration systems can use the technology in their PPE to monitor the workplace temperature, ensuring safe conditions for handling cold-sensitive products and preventing freezing risks. Rescuers, such as those involved in mountain or polar region rescue operations, can use the technology in their PPE. This allows them to monitor body and environmental temperature, ensuring they are aware of extreme cold conditions and taking measures to prevent prolonged exposure and harmful effects of intense cold. In laboratories or test facilities simulating extreme weather conditions, such as climate chambers with very low temperatures, temperature detection technology can be integrated into workers' PPE for real-time temperature monitoring, ensuring workers can work safely and efficiently in extreme conditions.

[0116] The more general and advantageous configurations of the present invention are described in the Summary of the invention. Such configurations are detailed in Detailed Description in accordance with other advantageous and / or preferred embodiments of implementation of the present invention.

[0117] As will be clear to one skilled in the art, the present invention should not be limited to the embodiments described herein, and a number of changes apparent to the person skilled remain within the scope of the present invention. The preferred embodiments shown above are combinable, in the different possible forms, being herein avoided the repetition all such combinations.

Claims

CLAIMS1. Sensor for temperature and radiation measuring, obtained by hot filament chemical vapor deposition (HFCVD), the sensor comprising a diamond surface, which comprises a nanocrystalline or a microcrystalline p-type semiconductor CVD diamond film, the film being on one side of the surface of an intrinsic or doped single-crystal silicon, Ge and GaN or ultra-hard ceramics like dense silicon nitride (SisN^, AIN, SiC. B4C, BN or WC flat substrate, and comprising ohmic contacts on the opposite side of said substrate.

2. Sensor according to claim 1 wherein the substrate comprises Vickers hardness values ranging from 12-30GPa and Young's Modulus between 200-500GPa.

3. Sensor according to any of the previous claims, further comprising a polycrystalline boron-doped diamond, optionally overlaid by a layer of non-boron-doped polycrystalline diamond.

4. Sensor according to any of the previous claims, wherein the diamond surface comprises a surface roughness from 0,012pm to 2pim with a microstructure variation between nanocrystalline and microcrystalline.

5. Sensor according to any of the previous claims wherein the diamond surface presents a thermal conductivity from 15-25 Wcm-iK-i.

6. Method for obtaining the sensor of any of the previous claims, comprising the steps: i) placing the substrate inside a hot filament chemical vapor deposition (HFCVD) system on a metal support located at a distance not greater than the distance between adjacent filaments; ii) a boron-doped diamond layer is grown on the substrate at a methane / hydrogen ratio of 0.5-10%, boron flux of 0- 5pl / min, argon flux of 0-50ml / min, pressure of 15-150mbar, substrate temperature of 600-900°C, filament temperature of 2000-2500°C, until an average thickness of 1-10 pm is obtained;Hi) turning the substrate over and placing it back into the HFCVD system with the uncoated surface facing tungsten filaments; iv) evaporating the tungsten filaments in primary vacuum at >5Pa for 2-4 minutes at a filament temperature between 1500-1900°C; v) adding hydrogen at a constant flow of 100 ml / min, at a total pressure of 5 kPa, with the filaments at 2100°C, for 2-3 minutes; vi) adding a carbon-containing gas to the hydrogen flow for 4-5 minutes at 4 ml / min, while the substrate is kept at 600- 700 °C, resulting in a tungsten carbide layer, where the tungsten carbide layer is transformed into the WC phase with hydrogen and methane gases, for one hour at a substrate temperature above 600°C; vii) mechanically removing the tungsten carbide layer from the two lateral and opposite surfaces of the substrate, using an abrasive disc;viii) adding an insulating protective layer to the boron-doped diamond.

7. Method according to the previous claim, wherein the substrate surface is scratched with diamond particles by ultrasonic or abrasive polishing of different sizes.

8. Method according to claims 6-7, wherein substrates are cut to the desired dimensions, mechanically or by laser.

9. Method according to claims 6-8, wherein substrates are subjected to a treatment comprising tetrafluoromethane plasma.

10. Method according to claims 6-9, wherein the substrate undergoes abrasion on a soft cloth with 0.5-1 pm diamond powder or is placed in an ultrasonic bath in a suspension of 0.5-1 pm diamond powder in 99.9% pure ethanol or other suspensions with diamond particle sizes ranging from 0.5pm to 60pm.11 . Method according to claims 6-10, wherein loose diamond particles are removed from the substrates with acetone in an ultrasonic bath for 10 minutes and subsequently in pure ethanol for 10 minutes.

12. Method according to claims 6-11 , wherein the boron source is boron oxide dissolved in ethanol at a concentration from 100 ppm to 15000, preferably 10000 ppm, to obtain a boron-containing solution which is placed in a reservoir pressurized, wherein the amount of boron-containing solution and ethanol supplied is controlled through a flow meter calibrated for the boron-containing solution.

13. Method according to claims 6-12, wherein the doped diamond layer is an electrical insulator, preferably a nondoped polycrystalline diamond layer, in particular a SisN4, or SiC>2 layer, preferably an AI2O3 layer, by cathodic spraying.

14. Method according to claims 6-13, further comprising the step of forming a notch (4) in the deposited tungsten carbide layer, connecting the two faces of the substrate, using a diamond cutting disk or wire and subsequently, optionally, a step of laser cutting.

15. Use of the sensor of any of claims 1-5 for monitoring the ambient temperature and radiation in personal protective equipment.

16. Use of the sensor of any of claims 1 -5 for detection and measurement of temperature and radiation in combustion and jet engines for the automotive and aerospace industry, natural gas exploration lasers, drilling, fuel cells or in deep ocean.

17. Use of the sensor of any of claims 1 -5 in platforms for immobilization of biomolecules, detection of chemical reactions in processes where heat exchange occurs, in chemical and biological environments or in dentistry.

18. Use of the sensor of any of claims 1-5 in nuclear reactors and in equipment for the diagnosis and treatment of cancer with highly ionizing radiation.

19. Personal protective equipment comprising the sensor of any of claims 1-5.

20. Helmet for real-time detection of temperature and radiation comprising the sensor of claims 1 -5 (A, C), an electronic comparator amplifier circuit (B) and a sound and visual alarm circuit, wherein all of said components are deployed in the upper area of the helmet.

21. Helmet according to the previous claim, wherein the sensor comprises a boron-doped diamond layer and a protective layer of undoped boron diamond.

22. Helmet according to claims 20-21, wherein the ceramic substrate is used, preferably silicon nitride (Si3N4), or a semiconductor substrate, preferably monocrystalline silicon.

23. Helmet according to any of claims 20-22, further comprising electronic comparator amplifier circuit comprising a microprocessor for data processing, the electronic comparator amplifier circuit preferably comprising 4 sensor connection inputs.

24. Helmet according to any of claims 20-23 with maximum dimensions of 20x15 cm, excluding the length of the connector wires to the sensors.

25. Helmet according to any of claims 20-24 further comprising four adjustable potentiometers, which are electrical resistances with values between 10-200,0000.

26. Helmet according to any of claims 20-25 further comprising an external battery optionally comprising a potential difference not exceeding 9V.

27. Helmet according to any of claims 20-26 further comprising a sound and visual alarm circuit comprising an alarm component, optionally audible, and / or means for emitting a high-intensity sound or a visual signal, preferably by emitting a flashing light signal.

28. Helmet according to the previous claim, wherein the sound alarm emits a sound with intensity not less than 80 dB.

29. Helmet according to any of claims 27-28, wherein the activation of the alarm occurs when the temperature measured by the sensor reaches an adjustable reference value, which is optionally individually set for each potentiometer.

30. Personal protective equipment comprising the helmet of any of claims 20-29.

Images