Preferably, the solid polymeric matrix is a thermoplastic polymer, thermoset polymer, elastomer polymer or resin. When manufacturing the inventive scintillation device, fluid precursors of said polymer matrix is used, such as thermosetting mono- or oligomers for a thermoset polymer; or a solidifyable fluid resin or polymerizable resin precursors, as precursors for the solid resin; thermoplastic polymer precursor for the thermoplastic polymer; or elastomer precursor for the elastomer polymer. Precursors may be fluid pre-polymer and/or fluid polymerizable monomers, including fluid oligomers.

Examples of a polymerizable prepolymer include a polyester-acrylate, an epoxy-acrylate, a urethane acrylate and a polyol-acrylate. The pre-polymers may be used singly or in combination. Examples of a monomer include polymethylolpropane tri(meth) acrylate, hexanediol(meth) acrylate, tripropylene glycol di(meth) acrylate, diethylene glycol di(meth) acrylate, pentaerythritol tri(meth) acrylate, dipentaerythritol hexa(meth) acrylate, 1,6-hexanediol di(meth) acrylate, neopentyl glycol di(meth) acrylate, isobornyl acrylate, (1-methyl-1,2-ethanediyl)bis [oxy(methyl-2, 1-ethanediyl)]diacrylate, 2-hydroxyethyl acrylate, or dipenyl-2, 4, 6-trimethylbenzoyl phosphine oxide.

The polymeric matrix of the composite may comprise, consist essentially of or consist of PDMS (polydimethylsiloxane), acrylate, acrylic resin, epoxy, epoxy resin, polyurethane, polystyrene, polysilicone, polysiloxane, olefinic copolymer, e.g. cyclic olefinic copolymer, or combinations thereof. The fluid pre-polymer may composite, may comprise or consist of the same materials or precursors thereof; if the precursor is or comprises a polymer than the molecular mass or polymerization degree shall be low enough for the polymer to remain fluid. The precursor may comprise or consist of polymerizable mono- or oligomers selected from siloxane, e.g. dimethylsiloxane, acrylate, epoxy, urethane, styrene, silicone, olefinic copolymer, e.g. cyclic olefinic copolymer, vinyl ether, or combinations thereof. Particularly preferably, the solid polymer is a polymer selected from (i) the group of elastomers comprising silicone rubber (Q), such as polydimethylsiloxane (PDMS), acrylic rubber (ACM), ethylene acrylic rubber (AEM), nitrile butadiene rubber (NBR), hydrogenated acrylonitrile butadiene rubber (HNBR), epichlorohydrin rubber (ECO); or (ii) the group of thermoplastics comprising polyacrylates, such as polymethyl methacrylate (PMMA), polystyrene (PS), polybutadiene (PB), polypropylene (PP), polyvinyl chloride (PVC), polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), cyclo olefin polymers (COP), cyclo olefin copolymers (COC), acrylonitrile butadiene styrene (ABS), polyimide (PI), polyetherimide (PEI), polysulfone (PSU); or mixtures thereof.

Generally, the fluid precursor of the solid polymeric matrix may be a combination of monomers, oligomers and (pre-) polymers of different chemical nature. The fluid precursors may be in combination with catalysts and other additives such as a photo-activator or photopolymerization initiator. Examples of a photopolymerization initiator include acetophenones, benzophenones, alpha-amyloxime ester, tetramethyl-thiurum monosulfide, and thioxanthones. Further, n-butylamine, triethylamine and poly-n-butylphosphine may be mixedly used as photosensitizer.

The metal halide may be in a composite or polymer as described in WO 2022/157279 A1 or in WO 2019/195517 A1 (all incorporated herein by reference).

Preferably, the solid polymeric matrix is transparent. This signifies that the polymer allows light to pass through the material without significant scattering even at a thickness of the polymer of at least 1 mm, so that at least 80% of the light emitted by the metal halide scintillator is transmitted. Preferably, the solid polymeric matrix is of a material that has a light transmission of at least 80% through a 1 mm thick sheet of the polymer. The light transmission shall be at the emission peak of the metal halide scintillator in the visible or infrared spectrum, preferably at a wavelength of 300 nm to 1200 nm, preferably of 350 nm to 1000 nm, more preferred of 400 nm to 800 nm, especially preferred of 420 nm to 700 nm.

Preferably, the composite fills an inner volume of a microchannel by at least 80 vol %, preferably at least 85 vol %, especially preferred at least 90 vol %, even more preferred at least 95 vol %, in particular preferred at least 98 volt. The inner volume may be bordered by walls on the sides extending along the lengths and flush (open) areas at the ends of the microchannels.

The metal halide absorbs radiation, e.g. ionizing radiation, and emits electromagnetic radiation. Alternatively, the composite may comprise a radiation absorbing agent. This agent ex-cites the metal halide when absorbing radiation. The metal halide in turn emits electromagnetic radiation, which may be detected.

Preferably, the microchannels comprise walls that absorb or reflect emitted light of the metal halide scintillator. Suitable materials may be used in the walls or as wall coating for absorbing or reflecting emitted light of the metal halide scintillator.

Preferably, the microchannels comprise walls that absorb x-rays. Suitable materials may be used in the walls or as wall coating for absorbing x-rays.

Example materials of the support and/or walls are: glass, plastic, metal and metal oxide. Possible x-ray absorbing materials are selected from plastic, preferably comprising moieties selected from the group of acrylates (e.g. polyesters of acryl), epoxies (polyepoxides), urethanes, styrenes, silicones and cyclic olefinic copolymers. Further x-ray absorbing materials comprise elements with high atomic number of more than 50 and/or visible light absorbing materials. Metal and metal oxide is preferably selected from titanium (oxide) or aluminium (oxide), without being limited to these. An example for light absorbing materials is titanium carbide. Examples of light reflective materials are metallic aluminium, titanium, silver, tungsten, PTFE (polytetrafluoroethylene) polymer, without being limited to these materials.

The walls may comprise one or more coatings for the absorption or reflection of emitted light and/or for the absorption of x-ray radiation. Such a coating, preferably an inner coating facing the microchannel, especially in case of a reflecting coating, may have a thickness 5 nm to 10 mm (single layer or multiple layers for the coating), preferably a thickness of 10 nm to 100 μm, even more preferred 50 nm to 10 μm.

In preferred embodiments, a side of the support, in which the microchannels have their ends, may be coated with an absorbing or reflecting layer for the emitted light of the metal halide scintillator-similar to the materials of the walls for absorbing or reflecting emitted light. This coating on the support side may be added after filling the microchannels with the composite.

The present invention further provides a radiation detection device comprising a scintillation device according to the invention and an electromagnetic radiation detector for detecting emitted electromagnetic radiation of the metal halide scintillator of the scintillation device. The electromagnetic radiation detector shall have a light transmitting connection (operative connection) to the scintillation device, in particular the metal halide scintillator, so that its emitted radiation can reach the detector. The connection may be a simple nearby location without obstruction, such as placing the detector on a side of the scintillation device or its support. The side shall face the endings of the microchannel. The microchannels preferably correspond to individual detection units of the detector, such as pixels. There may be overlapping microchannels and detection units, such as multiple microchannels per detection unit or multiple detection units per microchannel. The connection may also be via glass, glass fibers, fiber optics, mirror, optical glue or a direct light connection.

The electromagnetic radiation detector may be a photomultiplier tube (PMT) detector, thin film transistor (TFT) photodiode sensor, CCD sensor, a complementary metal oxide semiconductor (CMOS) sensor, or an indium gallium zinc oxide (IGZO), TFT sensor, and even more preferred a digital camera.

The radiation detection device may be provided in a radiation emission and detection system, comprising a radiation source and the inventive radiation detection device for detecting the radiation emitted by the radiation source. The radiation source shall be a source for radiation that is absorbed by the metal halide scintillator or another radiation absorbing agent in the composite so that the metal halide scintillator is excited to emit electromagnetic radiation, which in turn is detected by the detector. The radiation source may emit charged particles or high-energy photons (e.g. X-ray, gamma ray, UV light) with a wavelength of less than 600 nm, preferably less than 450 nm, especially preferred less than 380 nm, or less than 350 nm. The radiation source may be placed on a side of the support that comprises microchannel ends, preferably this is a side opposite to a side on which the detector is operatively connected to. Between the support and the radiation source there may be a sample space, i.e. a space in which a sample to be irradiated and measures is placed.

The invention also comprises using the inventive scintillation device. E.g. provided is a method of generating electromagnetic radiation comprising providing a scintillation device of the invention, exciting the metal halide scintillator of the scintillation device to emit electromagnetic radiation. Exciting the metal halide scintillator of the scintillation device to emit electromagnetic radiation may be with emit charged particles or high-energy photons mentioned above, e.g. from said radiation source. Also provided is a method of detecting radiation comprising providing a radiation detection device according to the invention, exciting the metal halide scintillator of the scintillation device to emit electromagnetic radiation, wherein exciting is with a radiation that is to be detected, and detecting the emitted electromagnetic radiation with the detector. Detection can be with the electromagnetic radiation detector mentioned above. The detector may be connected to the scintillation device as mentioned above.

The invention further provides a method of manufacturing a scintillation device according to the invention, comprising preparing a fluid mixture comprising a metal halide scintillator dispersed in a fluid polymer, fluid pre-polymer and/or fluid polymerizable monomers, filling said fluid mixture into microchannels of a support, and solidifying the fluid mixture in said microchannels.

Solidifying may comprise curing, crosslinking, and/or hardening of the fluid polymer, fluid pre-polymer and/or fluid polymerizable monomers. These terms define the formation of covalent bonds to generate a three-dimensional polymer network by forming covalent bonds between linear polymer chains (i.e. thermoplastics) or between multifunctional pre-polymers. Crosslinking may be carried out for example upon heating or by means of radiation, for example with UV light, gamma rays or X-rays, preferably in the presence of a hardener (also referred to as crosslinker, curative or curing agent) and/or a photo initiator. Solidifying forms the solid polymeric matrix as mentioned above and herein. The metal halide scintillator shall be dispersed in the fluid mixture and after solidifying also in the composite with the solid polymeric matrix.

The temperature of the fluid mixture during filling is preferably below 150° C., especially preferred below 100° C., more preferred below 75° C. The temperature may be room temperature. Such low temperature benefit handling (especially compared with prior art filling temperatures of 300° C.-500° C.) and also improve product quality as shrinkage is reduced and the filling factor is increased. Also, the method is gentler on the metal halide scintillator and support.

The inventive method uses a fluid mixture (precursor to the composite with the scintillator) to fill in the cavities of the microchannels or micro-pores. The invention avoids the need for several filling steps that are needed with solvent deposition methods that require multiple steps to fill the cavities. Hence the inventive method can be done much faster to obtain the final product.

The fluid mixture is introduced into the microchannels for filling. Preferably, the microchannels of the plurality are completely filled. This may be controlled by letting parts of the fluid mixture exit on opposing ends (opposing to the end used to introduce the fluid mixture). Exited fluid mixture may be removed. Alternatively, the corresponding exited solid polymeric matrix may be removed after solidifying.

This innovation provides several advantages over the current state-of-the-art scintillator devices. In particular, it is possible to provide a metal halide scintillator composite with high loading (e.g. 95 wt %) to fill a micro-pore array template comprising of open microchannels. Metal halides scintillators are an excellent alternative to existing scintillators. Previous technologies for high-resolution x-ray imaging with CsI (Tl) rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has limited the development of large-area scintillator screens. Additionally, in the case of Gadox scintillators for high resolution, they are usually thin and have high afterglow which hinders their fast-imaging application. On the contrary, metal halides can be synthesized and processed according to the invention even at room temperature, and their synthesis is easily scalable so that their production cost is lower. In addition, they are endowed with smaller afterglow, and their optical properties such as emission wavelength, and Stokes shift (namely the difference between the wavelengths of the maximum of the lowest energy absorption peak and the maximum of the highest energy emission peak), can be tuned. For these reasons, the present invention allows the quick production of high-performance, low-cost, large-area radiation detection systems.

The composite has a polymer matrix that is transparent to the scintillation light (emitted light of the scintillator). This polymer matrix acts as a binder for scintillator particles, facilitating the filling of the pores even at room temperature. The open channels ensure a more efficient filling of the cavities, minimizing any issues stemming from the wettability of the pores and trapped air, in contrast to what happens when using templates with wells. In this way, the use of additional solvent may be avoided, decreasing the time needed to fill the micro-channels/pores, and higher thicknesses can be achieved. Should a higher light output be desired, it is possible to increase the thickness of the micro-pore array template to have more scintillating materials/increase the length of the microchannels and the composite therein. E.g. scalability is easily achievable from few microns to some millimeters, an advantage that is not easily accessible with previous melting or solvent methods. Throughout the present disclosure, the articles “a”, “an”, and “the” are used herein to refer to one or more than one (i.e., to at least one) of the grammatical object of the article.

As used herein, words of approximation such as, without limitation, “about”, “substantial” or “substantially” refer to a condition that when so modified is understood to not necessarily be absolute or perfect but would be considered close enough to those of ordinary skill in the art to warrant designating the condition as being present. The extent to which the description may vary will depend on how great a change can be instituted and still have one of ordinary skill in the art recognize the modified feature as still having the required characteristics and capabilities of the unmodified feature. In general, but subject to the preceding discussion, a numerical value herein that is modified by a word of approximation such as “about” may vary from the stated value by e.g. +10%.

As used herein, the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. The “comprising” ex-pressions when used on an element in combination with a numerical range of a certain value of that element means that the element is limited to that range while “comprising” still relates to the optional presence of other elements. E.g. the element with a range may be subject to an implicit proviso excluding the presence of that element in an amount outside of that range. As used herein, the phrase “consisting essentially of” requires the specified integer(s) or steps as well as those that do not materially affect the character or function of the claimed invention. As used herein, the closed term “consisting” is used to indicate the presence of the recited elements only.

The present invention is further illustrated by the following examples, without being limited to these embodiments of the invention.

EXAMPLES
Example 1: MTF (Modulation Transfer Function) Calculation

MTF measurements were performed by using a lead bar Type 18c as a phantom placed between the X-ray source and the scintillators. The MTF was obtained by measuring the detected image contrast at a spatial frequency of 1 line pair per millimeter (lp/mm). The MTF at 11p/mm of sample #1 is used as a reference and arbitrarily set to 100%. The MTF at 11p/mm of the other samples are reported as relative values concerning the reference.

Example 2: Brightness measurements. Brightness values were calculated by measuring the grey values of the background-corrected detected images. The grey value of sample #1 was used as a reference and arbitrarily set to 100%. The brightness values of the other samples were reported as relative values with respect to the reference. The brightness uniformity was calculated as the standard deviation of the grey values of the measured pixels of the image, while the brightness values are the mean values of these measurements. In table 1 brightness uniformity is categorized by their % values according to the following scheme: good (>95%), moderate (95%-85%), bad (<85%).

Example 3: X-ray Measurements. X-rays were generated by using a Mini-X2 X-ray tube, with a voltage of 70 keV and a current of 140 mA. The pictures were taken using a PiCamera HQ module. The x-rays source and the camera were at a geometry of 90°, and a mirror was placed in between the X-rays source and the camera, at an angle of 45°. The X-rays source and the samples were placed at a distance of 10 cm, the samples and the mirror were placed at a distance of 20 cm, and the camera and the mirror were placed at a distance of 15 cm.

Example 4. Synthesis of Cs₃Cu₂I₅particles. Cs₃Cu₂I₅particles were synthesized using a previously reported method [DOI: 10.1002/adom.201901723]. CsI (3 mmol) and CuI (2 mmol) were dis-solved into Dimethylformamide (DMF) (4 mL) and stirred for 3 h at room temperature to form a precursor solution. 1 mL precursor solution was swiftly injected into 10 mL toluene under vigorous stirring. Immediately, white precipitates were formed in the mixed solution. The precipitated particles were separated by centrifuging at 8000 rpm for 10 min and washed with 5 mL 2-propanol two times. Finally, the resulting Cs₃Cu₂I₅polycrystalline powders were dried at 60° C. under the vacuum for 12 hours.

Example 5. Synthesis of Tl-doped Cs₃Cu₂I₅particles. Tl-doped Cs₃Cu₂I₅particles were synthesized following a previously reported method [DOI: 10.1021/acs. jpclett. 2c00456]. 3.115 g CsI, 1.524 g CuI, 0.01 g TI, 100 μL H₃PO₂, and 20 mL of DMF were stirred at 80° C. for 1 h and then collected as precursor solution. Then, the precursor solution was continuously added drop by drop to 20 mL toluene solution under vigorous stirring. Finally, the particles were centrifuged at 10000 rpm for 5 min, the supernatant was discarded and the precipitated particles were vacuum-dried at 30° C. for 12 h.

Example 6: Scintillator particles with fluid polymer precursor. Cs₃Cu₂I₅particles obtained from example 4 were ground into fine powder in an agate mortar and 0.85 g of the powder was mixed with 0.15 g of a UV curable resin (isobornyl acrylate; (1-methyl-1, 2-ethanediyl)bis [oxy(methyl-2, 1-ethanediyl)]diacrylate; 2-hydroxyethyl acrylate; dipenyl-2, 4, 6-trimethylbenzoyl phosphine oxide; i.e. an acrylic resin precursor including photoin-itiator), under vigorous stirring to form an 85 wt % resin.

Example 7: Tl-doped Scintillator particles with fluid polymer precursor. Tl-doped Cs₃Cu₂I₅crystals obtained from example 5 were ground into fine powder in an agate mortar, and 0.85 g of the powder was mixed with 0.15 g of a UV curable resin (as in Example 6) under vigorous stirring to form 85 wt % resin. To compare the effect of the pixelation on the resolution and brightness of the scintillator screens, different templated screens filled with doped and non-doped Cs₃Cu₂I₅were prepared. The results are shown in Table 1.

Example 8: Supported scintillator screen. A porous glass with a surface of 5×5 cm², a thickness of 1 mm, a pore diameter of 10 μm, and an open area ratio of 75% was used as screen (or plate) template. The pores form microchannels with a length corresponding to the thickness of the support template and a width corresponding to the pore diameter. The microchannels were filled by the various methods as described for the following samples (comparative methods: precursor solution method, samples #1 and #2; melt method, samples #3 and #7; solvent method, samples #5 and #6; inventive composite method: samples #4, #8 to #10).

Sample #1 (comparative example). The first sample was prepared by forming the particles from a salt stock solution (CsI 0.6 M, Cul 0.4 M) in DMF in the cavities of the templated screen by slow evaporation of DMF for one week at room temperature. This sample showed good brightness which is due to the formation of large crystals and lower particle boundaries that lead to lower light scattering and the sample showed very good brightness uniformity as the standard deviation of the grey value was <5% (uniformity>95%). This sample was used as the reference to compare the brightness and the resolution of other films.

Sample #2 (comparative example). The second sample was prepared by filling the cavities of the templated screen with an (0.1 mg/ml) suspension of the Cs₃Cu₂I₅(prepared as in example 4) in cyclohexanol in several steps followed by removing the solvent within a few minutes at 70° C. This sample showed lower brightness compared to the reference sample due to the lower filling factor despite multiple filling steps and scattering of light inside the channels.

Sample #3 (comparative example). The third sample was prepared by filling the template with the melted Cs₃Cu₂I₅(prepared as in example 1) at 410° C. within two hours followed by cooling to room temperature within several hours. The filling method for this sample was not efficient and the brightness of the film was not uniform across the screen.