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EP-3423817-B1 - DIAMOND-BASED SENSOR DEVICE FOR USE IN HOSTILE ENVIRONMENTS

EP3423817B1EP 3423817 B1EP3423817 B1EP 3423817B1EP-3423817-B1

Inventors

  • JACKMAN, Richard B
  • JENNINGS-MOORS, Ralph
  • PAKPOUR-TABRIZI, Alex
  • PARFITT, William
  • WELCH, Joseph O.

Dates

Publication Date
20260506
Application Date
20170303

Claims (13)

  1. A sensor device configured to sample data from a fluid in a sealed environment, wherein the sensor comprises: a housing (7; 30; 60); a diamond (8; 19; 22; 25; 65); a first sealing device (6; 14) located on a first side of the diamond, the first side of the diamond being a side configured to interface directly with the sealed environment; a second sealing device (9; 17) located on a second side of the diamond, the second side of the diamond being a side opposite the first side, wherein the second side of the diamond is configured to be sealed apart from the sealed environment; and a conduit (10; 18; 20) configured to receive one or more electrical connections (56); wherein the diamond comprises one or more electrically conducting pathways extending from the first side of the diamond to the second side of the diamond, wherein the electrical conducting pathways are graphitic in nature.
  2. The device according to claim 1, wherein the diamond is shaped approximately like a disk, and one face of the diamond directly interfaces with the sealed environment, and optionally wherein: the diameter of the diamond is no greater than 30mm, and/or the thickness of the diamond is no greater than 4mm.
  3. The device according to any preceding claim where the diamond is either polycrystalline or monocrystalline.
  4. The device according to any preceding claim where the electrical properties of the diamond have been adjusted through the purposeful inclusion of impurities, and optionally wherein: the impurities include but are not limited to boron, phosphorus and/or graphitic material; and/or the impurities are distributed within the diamond to provide localized electrical properties, and further optionally wherein concentric rings of impurities across the surface of the diamond cause circular variation in the electrical properties on the surface of the diamond; and/or the impurities are distributed within the diamond to generate one or more layers of insulating, conducting or semiconducting diamond.
  5. The device according to any preceding claim where the diamond is configured to allow light with wavelengths in the range 0.23-100µm to pass from the first side of the diamond to the second side of the diamond, or vice versa.
  6. The device according to any preceding claim where the diamond is coated in an anti-reflective coating, or where the shape of the diamond is configured to be anti-reflective, to enhance transmission of low intensity optical signals.
  7. The device according to any preceding claim wherein the first sealing device comprises a leak resistant seal to preserve the sealed environment located on a front side of the diamond, and optionally wherein either: the seal is a mechanical seal, optionally formed by gaskets, O-rings or c-rings; or the seal is a fusion seal, optionally a braze, weld or frit seal.
  8. The device according to any preceding claim, further comprising optical and/or electrical connections located on a rear side of the diamond, the rear side of the diamond being opposite to, and sealed from, the front side of the diamond.
  9. The device according to any preceding claim wherein the housing is adapted for insertion into a larger structure containing the sealed environment through integration into a pipe-section.
  10. The device according to any preceding claim where the housing is in the form of a mechanical bolt, and optionally wherein optical and electronic components are contained within the bolt.
  11. The device according to any preceding claim further comprising optical and/or electronic connectivity for linking to an external storage unit located outside the sealed environment.
  12. The device according to any preceding claim, wherein the diamond acts as a passive window for passing a sensing signal into and/or receiving a sensing signal from the sealed environment, and optionally wherein the sensing signal comprises an optical (visible or infrared) or electrical signal.
  13. The device according to any preceding claim, wherein the diamond acts as an active sensing device, such as for performing electrical measurements of the fluid in the sealed environment.

Description

Field The present application relates to a sensor device operable to sample data from a fluid in a sealed environment. Background Analysing or monitoring the composition of gases or liquids in harsh environments, such as water cooling systems that may be at high pressures, such as 300 bar, and/or elevated temperatures, such as 350 °C, is currently achieved through occasional manual sampling and ex situ analysis operations. It would be highly advantageous to have a sensor in direct contact with the fluid medium capable of giving real-time continuous measurement capability. Such a device would find use within, for example, chemical or radiological reactor environments where, in addition to elevated temperatures and/or pressures, an aggressive chemical and/or radiological environment can be encountered which is detrimental to currently available sensor materials. It is established that diamond, both in its intrinsic state, where it is electrically insulating, or doped with foreign species such that it shows electrical semiconducting or electrical metallic properties [1], can be useful as an active material for sensing in hostile environments. In particular, it has been shown that diamond-based sensors are capable of measuring the oxygen content [2-4] and pH of water [5,6] and can lead to the detection of radio-nuclides in water or other fluid environments [7-9]. The most accurate method to determine pH is to use an ion-sensitive field effect transistor (ISFET). Such a device is similar to a metal-oxide semiconductor field effect transistor (MOSFET), but without a gate, with the gate voltage being applied to the solution and the threshold voltage being modified by the presence of ions in the solution. Diamond ISFETs can be fabricated using, for example, diamond containing boron [10]. In this example, thick boron-doped diamond (BDD) regions form the source and drain regions of the ISFET, with a thinner BDD material acting as the channel of the ISFET. It is also possible to use the impurity (for example, boron) doped diamond to measure the electrical conductivity of an adjacent fluid [11,12]. Diamond can tolerate a large voltage range before the onset of the redox reaction involving the unwanted production of hydrogen and oxygen in an aqueous environment. This so-called electrochemical 'window' enables operation of sensors based on electrochemical effects at extended voltages in fluid environments with a larger voltage range than is normally encountered with other electrochemical sensor materials. In turn this means a large range of species can be detected through this approach with improved sensitivity [13-15]. Although the use of BDD as the working electrode of such a sensor can lead to the electrochemical determination of oxygen [16], the sensitivity of the measurement is significantly improved if the BDD is coated with, for example, platinum (Pt) nanoparticles [17]. Further, diamond surfaces can be chemically modified to support a chemical or biological species which can be used to further enhance the range of species that the sensor can detect. This process, often termed 'functionalisation', can also lead to very stable sensor performance compared to the utilisation of this approach with other materials [18]. It is well-known that diamond is also a good window material for the transmission of visible and infra-red light, with little or no loss of light intensity that commonly occurs with other materials. The small number of non-diamond materials that are transmissive to visible and infra-red lack chemical and/or mechanical resilience. For example, calcium fluoride (CaF2) and zinc selenide (ZnSe) are commonly used infra-red window materials but only display a Knoop hardness value of 158 and 120 respectively, compared to 7000 for diamond. It has been previously reported that such an optical component if sufficiently large may find several applications [19,20]. For example, the use of a diamond as a window material may enable optical spectroscopic determination of events occurring in a fluid beyond the window boundary. The application of a light source through the window for sensing applications in elevated temperature aqueous environments has been previously described, for example in the case of Raman spectroscopy [21,22]. As outlined above, diamond lends itself well both to sensing (electrically and optically) and to excellent resilience in harsh environments. However, there has been comparatively little work on providing a resilient housing for such diamond sensors in harsh environments. EP 2 686 672 A1 relates to a diamond-based electrochemical sensor. US 6 115 528 A relates to a fibre optic probe assembly for Raman spectroscopy for use in hostile environments. Summary The present application provides a sensing device for use in a harsh fluid environment, as defined in claim 1. The sensing device includes a diamond (diamond element) appropriately modified and packaged for making electronic or optical measur