Heat sink for a cryogenic cooling device

Abstract

A heat sink 61 comprising a heat transfer 62 component comprising a metal and having a first thermal conductivity. Wherein the heat transfer component comprises at least one cavity. At least one therm

Description

10 02 25 FIELD OF THE INVENTION The present disclosure relates to a device that can provide a cooling effect. In some cases, 5 such a device can be used to allow pain free injection in clinical settings. The device is handheld, light weight and uses cogenetic effects for causing local anaesthetic effects on the injection site within a few seconds. Such an effect can be provided at below 10 degrees Celsius, or preferably below 0 degrees Celsius, for example. The present disclosure also relates to heat sink design and thermal improvements for improving the efficiency of such a device. The disclosure also relates to disposable 10 covers suitable for the device, which can ensure sterility of the component which contacts tissue in a clinical environment, whilst still providing adequate thermal transmission characteristics. BACKGROUND The skin is known to be the largest organ in the human body, it weighs around 4 kg and has a 15 surface area of around 2m2. It functions as the main interface with the environment and protects its underlying structures from damage and diseases. The layers of the skin are epidermis, dermis, and hypodermis which has high fat content. Typically, one would assume that the perception of pain is rooted in the exaggerated stimulation of the same receptors that are responsible for other somatic sensation. However, this is 20 not what happens; the perception of pain (i.e. Nociception) is associated with specific receptors and pathways. Therefore, informing the brain of the dangers applied by noxious stimulus deviates substantially from response to innocuous somatic sensory stimuli. Many aspects of the physiology and pharmacology of the pain are imperfectly understood which makes nociception a very active research area. The nerve cell endings that convey the sensation of pain are called nociceptors. They 25 communicate stimuli to receptor potential, which then discharges afferent action potential. Similarly, to other somatic sensory receptors which arise from cell bodies located in dorsal root ganglia that send on axon process to the spinal cord and into the periphery. Given the unspecialized free endings of the peripheral nociceptive axon thermals, it is common to categorize nociceptors based on the properties of their axons. The axons of nociceptors have a slow conduction velocity as they are either 30 unmyelinated or slightly myelinated. Despite the fact that conduction of nociceptive information is rather slow, there are slow and rapid pathways with conduction velocities of up to 20 m / s. Blocking the conduction of the peripheral nerve is the main mechanism that relieving pain with low temperature is based upon. Advancements in the field have led to development of long and fine probes to enclose stimulators and thermocouples; and allow for insertion through the skin for local 35 freezing of nerves. These developments led the discovery of cryoanalgesia, in which it has been determined that analgesia for a prolonged period of time can be produced through freezing of peripheral nerve. Put another way, the mechanism of cryoanalgesia is based on slowing or complete blockage of the conduction of action potentials in Ab and C-fibre nociceptors. It is also known that a thermo-electric device refers to a device where a voltage or current through the device causes a thermal difference across the device, and vice versa (via the Seebeck and Peltier effect). A thermo-electric cooler (TEC) is a solid-state heat pump which transfers head from one side to the other side and the direction of the heat flux, depending on the direction of the current. TEC are typically used to cool down electronics, where the hot side of the TEC is optimized by designing a thermal management system which meets the specified design requirements and constraints. However, one of the main issues with a TEC device is a low coefficient of performance (COP), and it has not previously been possible to effectively reach cryogenic temperatures (below 10 degrees or below 0 degrees Celsius) in a lightweight handheld device, which is suitable for cooling an area of skin for pre-injection anaesthesia. Heat sinks for providing a heat extraction effect are also generally known. However, it is not known to provide a heat sink having inserts comprising diamond into cavities of a metal body of the heat sink, so as to provide improved thermal properties in a small and lightweight footprint, suitable for handheld applications. As background, WO 2018 / 078371 describes a cooling device for cooling a subject’s tissue or organ surface, the device comprising a handle and a head. The head comprises an electrical cooling element for cooling the subject’s tissue or organ surface. The device also comprises a controller configured to: receive the initial temperature of the subject’s tissue or organ surface; determine a cooling temperature based on the initial temperature of the subject’s tissue or organ surface and a target temperature; and control the cooling element to generate the cooling temperature. However, the thermal characteristics of the device of WO 2018 / 078371 are not suitable for providing consistent cryogenic temperatures at low power. For example, the head is coupled to the handle via a mechanical interface, which allows the head to rotate relative to a longitudinal axis of the handle. Such an interface would result in significant thermal losses which would drastically reduce the efficiency of the device. Moreover, there are fins provided for improving heat dissipation, but these are connected to the head of the device (i.e. the device which contacts the subject and should be brought to a cold temperature). In other words, the heat dissipating elements are not connected to the portion of the device which is configured to get hot, but rather to the portion of the device which is configured to get cold. As further background, US 2019 / 0167916 provides a handheld cryoanesthesia or analgesia device for cooling a target area on cutaneous membranes, mucous membranes, and tissue of the mucocutaneous zone having an elongated body and a thermoelectric cooling system disposed within the elongated body. The thermoelectric cooling system is configured to physically contact and thermally couple the target area of the cutaneous membranes, mucous membranes, and tissue of the mucocutaneous zone to induce cryoanesthesia or analgesia. The thermo-electric cooling system includes a thermally-conductive cold tip, a thermally conductive cooling power concentrator thermally coupled to the cold tip, at least one Peltier unit module thermally coupled to the cooling power concentrator, a heatsink thermally coupled to at least one Peltier unit module, a power source, at least one thermal sensor, and a controller operably outputting a control signal to the Peltier unit module to maintain a predetermined temperature. Such a device is specifically configured to deliver ocular anaesthesia to an ocular surface, and thus requires a significantly smaller conductive tip to provide the cooling effect. US 2019 / 0167916 also mentions that Peltier modules have a low coefficient of performance, but avoids this problem by using a cooling power concentrator for collecting the cooling power of multiple Peltier modules and concentrating this cooling over a small area. Thus, US 2019 / 0167916 does not disclose that it is possible to improve the thermal characteristics of a device in a way which would allow a single TEC or Peltier module to provide the desired cooling effect, let alone for a device having a larger contacting surface area which is suitable for contacting the skin. SUMMARY According to one aspect of the invention, there is provided a handheld cooling device, comprising: a housing; a thermo-electric device located within the housing; a cooling component thermally coupled to a cold junction of the thermo-electric device; and a heat extraction system coupled to a hot junction of the thermo-electric device. During operation, the thermo-electric device is configured to cool the cooling component down to a first temperature, the first temperature being less than or equal to 10 degrees Celsius. The handheld cooling device has a weight less than 2 kg. It may be understood that a handheld device refers to a device which can be easily picked up and supported by one or both hands of a user. A thermo-electric device refers to a device where applying electric current running the device can cause the device to provide a heating or cooling effect, and vice versa. It has been shown for the first time that a handheld cooling device capable of cooling a cooling component down to 10 degrees Celsius or lower is possible with this small of a size (i.e. under 2kg of weight). This improvement in efficiency is advantageous because there are clear ergonomic advantages to having a handheld device with certain size and weight parameters, whilst still being able to achieve low temperatures for cooling an object brought into contact with the cooling component. Such a device has many uses, including, e.g. applying a cooling effect to a piece of tissue to work as a cryogenic anaesthetic, thereby obviating the need for topical or general (pharmaceutical) anaesthetics in a medical environment. In one embodiment, the handheld cooling device has a volume less than 5,000,0000 mm3. The volume referred to in the above claim is an actual volume, i.e. the amount of space that the handheld cooling device occupies. It has been shown for the first time that a handheld cooling device capable of cooling a cooling component down to 10 degrees Celsius or lower is possible with the weight and the volume parameters described herein. In one embodiment, the heat extraction system comprises a heat sink. The presence of a heat sink is used to extract heat from the hot junction of the thermo-electric device. By keeping the temperature difference between the hot junction and the cold junction of the thermo-electric device to a minimum (i.e. by keeping the hot junction as cool as possible), a higher efficiency of the thermo-electric device can be achieved. Whilst a number of heat extraction systems could be used to extract heat from the hot junction (including, e.g., a liquid cooling system), the presence of a heat sink to provide such functionality is advantageous because it is a passive heat extraction system, and can be provided entirely on the handheld device itself without any additional connections. In one embodiment, the heat sink has a weight between 60g to 1190g and / or a density between 2.1g / cm3to 9.5g / cm3. It has been found that a heat sink having the above physical parameters can be added to a handheld cooling device, and provide the necessary heat extraction effect without adversely affecting the ergonomics of the device. In one embodiment, the heat sink has a bounding box volume within a range of 4,000 mm3 to 600,000 mm3, optionally within a range of 12,500 mm3 to 450,000 mm3, or further optionally within a range of 100,000 mm3 to 350,000 mm3 In one embodiment, the heat sink has an actual volume within a range from 4,000mm3 to 122,000mm3, optionally within a range of 10,000 mm3 to 75,000 mm3, or further optionally within a range of 30,000 mm3 to 60,000 mm3. It should be understood that a bounding box volume (or a bounding volume) refers to the smallest volume of a box which completely contains the object. In the case of the heat sink, the bounding box volume captures the overall size of the heat sink, including any air gaps between pins or fins of the heat sink, for example. In contrast, the actual volume refers to the actual volume of the physical heat sink (i.e. excluding any airgaps present between pins or fins of the heat sink). In one embodiment, the heat sink has a surface area in a range from 27,000 mm2 to 163,000 mm2. The surface area of a heat sink is an exterior surface area that is in contact with a cooling medium surrounding it, such as air. It is understood that a higher surface area is typically associated with improved performance of the heat sink. In one embodiment, the actual volume divided by the surface area is in a range from 0.8mm to 1,5mm. With selecting heat sinks suitable for the handheld cooling device, it has been found that the ratio of volume to surface area within this range is the optimal trade-off between heat sink performance and size. In one embodiment, the heat sink has a thermal conductivity in a range from 150 Watts per meter Kelvin (W / m.k) to 3500 W / m.K. The thermal conductivity of a material is a measure of its ability to conduct heat, and is measured in Wm"1K"1. Where the heat sink consists a single material, the thermal conductivity of the heat sink may be equivalent to the thermal conductivity of the single material. The thermal conductivity of the entire heat sink (which may include a plurality of materials) may also be measured through applying the Maxwell-Eucken equation. Further steady-state methods (e.g. Searle’s bar method), time-domain methods (e.g. a transient hot wire method, a transient plane source method, a modified transient plane source method), or frequency-domain methods (e.g. 3w-method) can also be used to determine the thermal conductivity. In one embodiment, the handheld cooling device comprises an internal power source. The internal power source refers to an electrical power source (i.e. a source configured to deliver a voltage or a current), and which is internal to the handheld cooling device (i.e. within the housing). It is configured to deliver electrical power to the thermo-electric device. It further may be used to power additional components or peripherals within the device (e.g. a processor, a display, etc.). The thermo-electric device may comprise two terminals (an input and a return) for receiving the electric power, and allowing current to flow through the device. In one embodiment, the internal power source is a battery. It may be understood that the battery may comprises one or more battery cells, and each of the battery cells may be rechargeable (i.e. secondary cells). In one embodiment, the operating frequency of the device is 10Hz or below. In some cases, the device can also be operated with DC (i.e. direct-current, non-oscillating) signals. In one embodiment, the battery operates with a power of less than or equal to 200W, and wherein the battery has a bounding box volume of less than 1000cm3 and a weight of less than 3kg. In one embodiment, wherein the battery operates with a power of less than 100W, less than 70W, or less than 50W. Due to the thermal efficiencies of the handheld cooling device, a smaller battery can be used to provide the cooling effect, thus leading to a more lightweight and ergonomic cooling device. By removing space in the device typically reserved for a power source, the additional space can be utilized to increase the size of the internal components (e.g. the heat sink), or additional components can be added to the handheld cooling device to add further functionality. In one embodiment, the handheld cooling device is a wireless device during operation. A wireless device refers to a device that can be operated entirely without any additional connections (e.g. electrical wires for power, fluid lines for liquid cooling, etc.). In one embodiment, the first temperature is less than or equal to 0 degrees Celsius. By providing sub-zero temperatures, the anaesthetic effect applied to tissue can be improved, and the overall cooling effect to non-tissue objects is also generally improved. Such a cooler temperature also speeds up the time required to cool an object down to the requisite temperature. In one embodiment, the device further comprises one or more fans located at least partially within the housing. The presence of fans can be used to improve the air flow over the exposed surface area of the heat sink, thus providing an improvement to the efficiency of the heat extraction system (thus, keeping the hot junction of the thermo-electric device cooler, and in turn, improving the cooling efficiency). In one embodiment, a flow rate of the one or more fans at zero static pressure is in a range from 0.1 m3 / min to 10 m3 / min. In one embodiment, the handheld cooling device further comprises a handle attached to the housing, optionally wherein the handle is in a pistol-grip configuration. Such a handle is advantageous for single-handed operation, which is advantageous for improved ergonomics during use. In some cases, the handle extends away from the bottom of the handheld device (i.e. the side of the device opposite the fans). In one embodiment, the thermo-electric device consists of a single thermo-electric device or consists of two thermo-electric devices. Due to the thermal and electric efficiencies afforded by design of the handheld cooling device, a single thermo-electric device can be used to provide the requisite cooling effects. In some cases, a second thermo-electric device can be used in parallel or in series so as to further improve the efficiency of cooling, at a trade-off of increased electrical power draw. In one embodiment, the handheld cooling device further comprises a processor and a memory, the memory storing instructions fora control algorithm, wherein the processor is configured to execute the control algorithm to operate the thermo-electric device. By providing a processor in the handheld cooling device, power delivered to the thermoelectric device can be controlled in accordance with a control algorithm (as opposed to power being automatically delivered to the thermo-electric device in a constant fashion when the device is turned on). This control algorithm can be stored in the memory of the device, which may be a separate component or which may be incorporated within the same device as the processor. It is also understood that different rates of cooling can be provided to cool the object. For example, when the cooling component is taken to temperature (below 10 °C and then brought into contact with a warmer object (e.g. skin temperature of between 33.5 and 36.9 °C), the immediate effect is that the cooling component will warm up whilst the skin will cool down. Thus, a control algorithm can be provided to control a rate of temperature change, in order to bring the skin temperature down to the desired temperature of the cooling component (i.e. below 10 °C). Such a control algorithm may be entirely independent of any specific temperature sensing. The control algorithm may be pre-programmed into memory and configured to provide a certain amount of current to the thermo-electric device at certain times so as to provide a desired rate of cooling. The rate of cooling may vary across the length of the application to the object, so as to, e.g., improve patient comfort. In one embodiment, the cooling component is configured to extend from the housing. The cooling component is the device brought to low temperatures (i.e. below 10 degrees Celsius) for the purpose of cooling an object (e.g. tissue). Whilst in some cases, the cold junction of the TEC can be directly exposed at the edge of the housing (and thus, the cooling component and the cold junction are one and the same), by providing a separate cooling component configured to extend from the housing, the cooling component can be more easily positioned against the object and the cooling effect will not be impacted by the housing itself. In one embodiment, the cooling component is configured to be brought into contact with a tissue to apply a cooling effect to the tissue. By using the cooling component to cool tissue, an anaesthetic effect can be provided, which is useful for reducing pain in injections, vaccinations, etc. Such an anaesthetic effect can be applied rapidly on-site, without any need for pharmaceutical interventions, and the anaesthetic effect improved patient compliance with receiving injections or vaccinations (as some patient may be unwilling or nervous to receive such treatments due to the perceived pain). In one embodiment, the cooling component is configured to be brought into contact with a fluid to apply a cooling effect to the fluid. In some cases, it may be advantageous to apply a cooling effect to a fluid in the body (e.g. blood, mucus, etc.) or to a separate liquid (e.g. a beverage or a chemical solution) to provide a rapid cooling effect with the same wireless device. In one embodiment, the handheld cooling device further comprises one or more sensors communicably coupled to the processor, the one or more sensors configured to identify a point of contact between the cooling component and the tissue. In one embodiment, the processor is configured to execute and / or adjust the control algorithm based on the point of contact identified by the one or more sensors. By providing sensing capability into the device, the processor of the device can determine, based on the sensors, when the cooling component has been brought into contact with tissue. This can be used to determine when to start the cooling process, or can be used to help regulate the rate of cooling. In some cases, the thermo-electric device will not be powered until the cooling component is brought into contact with tissue. In other cases, the cooling component will already be at a cool temperature (i.e. below 10 degrees C) before being brough into contact with tissue, and the sensors will inform the processor when to initiate a control algorithm for bringing the tissue down to the desired temperature (i.e. below 10 degrees C). In one embodiment, the control algorithm is configured to maintain an initial temperature on the cooling component before the point of contact is identified, and reduce the temperature on the cooling component once the point of contact is identified. A variety of different sensors can be used to provide contact information to the processor. In one embodiment, the one or more sensors comprise a contact sensor or a non-contact proximity sensor, optionally where the contact sensor is a conductive sensor or a pressure sensor, and further optionally where the non-contact proximity sensor is a capacitive sensor, an inductive sensor, or an infrared sensor. In one embodiment, the processor is configured to determine an amount of time that the cooling component is in contact with the tissue and / or fluid. This information can be displayed to a user via a user interface, and / or used by the control algorithm as a control element in a feedback, path. In some cases, it can be possible to rely on the elapsed time of treatment to obviate the need for a temperature sensor on the cooling component of the device. In one embodiment, the handheld cooling device comprises a temperature sensor positioned within 1 cm from a contacting surface area of the cooling component for sensing the temperature of the cooling component, and wherein the processor is configured to receive a temperature signal from the temperature sensor. The temperature sensor may include an NTC and / or a thermocouple. In one embodiment, the handheld cooling device further comprises a user interface for providing information to a user of the device, optionally where the user interface comprises a display screen and / or one or more lights. A user interface can be used to assist a user of the handheld cooling device in providing a cooling treatment. For example, the user interface can be used to indicate when the cooling component is at a certain temperature and ready to be brought into contact with an object. It may also include an indication of the time elapsed since being brought into contact with an object, for example. In one embodiment, the housing comprises a plastic material and / or a metal material. In one embodiment, the housing is thermally coupled to the heat extraction system. The benefit of this thermal coupling is to further improve the heat extraction capability of the heat sink. For example, if the entire chassis of the device is made of metal, except for a portion held by the user, greater heat extraction can be performed (which improves the efficiency of the device as a whole). Of course, when a metal chassis of the device is used, particular care must be taken to ensure that the electrical elements inside the device cannot short to the metal chassis (e.g. placed within insulating enclosures within the chassis). In one embodiment, the handheld cooling device comprises a first thermal interface material interposed between the thermo-electric device and the cooling component and / or a second thermal interface material Interposed between the heat extraction system and the thermo-electric device. In one embodiment, wherein the heat extraction system does not comprise any fluids, with the exception of any thermal interface material. Such a heat extraction system can be an entirely passive system without the need for driving active fluids for cooling. According to a further aspect of the invention, there is provided a method of operating a handheld cooling device, the handheld cooling device comprising a housing; a thermo-electric device located within the housing; a cooling component thermally coupled to a cold junction of the thermoelectric device; and a heat extraction system coupled to a hot junction of the thermo-electric device; wherein, during operation, the thermo-electric device is configured to cool the cooling component down to a first temperature; and wherein the first temperature is less than or equal to 10 degrees Celsius, wherein the handheld cooling device has a weight less than 2 kg, the method comprising: cooling the cooling component down to the first temperature by providing electrical power to the thermo-electric device; bringing the cooling component into contact with an object desired to be cooled, optionally wherein the object comprises an animal or human tissue. In one embodiment, the method further comprises bringing the cooling component into contact with the tissue; identifying, with one or more sensors, a point of contact between the cooling component and the tissue; executing and / or adjusting, with a processor, a control algorithm based on the point of contact identified so as to cool the tissue with the control algorithm or the adjusted control algorithm. According to a further aspect of the invention, there is provided a handheld cooling device, comprising: a housing; a thermo-electric device located within the housing; a heat extraction system located at least partially within the housing and coupled to a hot junction of the thermo-electric device; and a cooling component, the cooling component comprising a contacting surface area configured to be brought into contact with tissue to apply a cooling effect to the tissue. The cooling component is unitary and directly connected to a cold junction of the thermo-electric device. The contacting surface area has an area of greater than or equal to 25 mm2 and optionally less than or equal to 1500 mm2. By providing a cooling component which is both unitary and directly connected to the cold junction (i.e. thermal connected to the cold junction, with or without a thermal interface material), the thermal properties of the device can allow the cooling component to be brought down to low temperatures (e.g. below 10 degrees Celsius), which would not be possible with other arrangements. Put another way, the thermal improvements of the present invention allow the temperatures to be reliably achieved for a device having a large contacting surface area, which can be used for a large area of effect on the skin of a patient. The contacting surface has a range of areas as described, which allows for an adequate cooling effect to tissue, for the purpose of anaesthesia for injections or vaccinations, for example. Such an area has also been shown to not negatively impact the overall thermal properties of the cooling component. In one embodiment, the cooling component further comprises an elongated portion between the contacting surface area and the cold junction of the thermo-electric device, the elongated portion configured to extend from the housing. The elongated portion may be generally rectangular in shape, although it is not limited as such. The cooling component is the device brought to low temperatures (i.e. below 10 degrees Celsius) for the purpose of cooling an object (e.g. tissue). Whilst in some cases, the cold junction of the TEC can be directly exposed at the edge of the housing (and thus, the cooling component and the cold junction are one and the same), by providing a cooling component with an elongated portion (i.e. a portion configured to extend from the housing), the cooling component can be more easily positioned against the object and the cooling effect will not be impacted by the housing itself. In one embodiment, the thermal resistance along the length of the elongated portion of the cooling component is greater than or equal to 50,000 K / W, optionally less than or equal to 25,000 K / W, less than or equal to 5,000 K / W, or less than 1,000 K / W. Thermal resistance refers to the ability of a material to oppose to heat current, measured in K / W. It is the inverse of thermal conductance, which is the ability of a material to conduct heat. It may also be defined as the ratio of the temperature difference between the two ends of the elongated portion (which can be made of a certain material) to the rate of heat flow per unit area. Whilst it might be assumed that the lowest possible thermal resistance of the elongated portion (and of the cooling component as a whole) would be desired, it has been determined instead that a range of higher thermal resistances are advantageous for improving performance of the cooling effect. Thermal resistance is a directional parameter, and the above parameters refer to the thermal resistance in a direction along the length (i.e. extending away from the TEC towards the contacting surface area) of the elongated portion. In one embodiment, the elongated portion of the cooling component has a uniform thickness, the thickness measuring in a direction extending away from the cold junction of the thermo-electric device (in a direction defined from the hot junction of the TEC towards the cooling component, via the cold junction of the TEC). Whilst other geometries are possible for the cooling component, an elongated portion with a uniform thickness extending from the housing is advantageous for ensuring an evenly distributed heating (or cooling) current along the length of the elongated portion. In one embodiment, the entire cooling component has the same uniform thickness. That is, the contacting surface area formed in a distal tip, the elongated portion, and the portion of the cooling component which contacts the TEC can all have the same thickness. This improves the thermal properties and ability to transfer heat (or cold) from the TEC to the contacting surface area in a reliable way. In one embodiment, the thickness of the elongated portion is greater than or equal to 0.2mm, greater than or equal to 0.35mm, or greater than or equal to 0.5 mm. In one embodiment, the cooling component is solid and does not comprise any holes. By providing a solid cooling component, the thermal properties are improved over solutions which include such a hole. Thus, it has been shown that providing a solid contacting surface area to tissue is desired so as to provide an effect anaesthetic. In one embodiment, the cooling component is formed from a planar sheet of a thermally conductive material, optionally wherein the cooling component has a bend at a distal end of the cooling component. For example, taking an approximately rectangular prismatic sheet of material, and bending one end at an angle of roughly 40 to 60 degrees, a roughly “L-shaped” cooling component can be easily formed, having an elongated portion and the bent portion can act as the contacting surface area. The contacting surface area may have any shape, including e.g. rectangular, semi-circular, etc. In one embodiment, at least a portion of the cooling component is coated with an insulative material, preferably an aerogel, so as to increase the thermal resistance between the cooling component and ambient air, optionally where the at least a portion of the cooling component that is coated is the elongated portion of the cooling component. Whilst it is advantageous to have a thermal resistance along the length of the elongated portion within a certain range, it is also advantageous to prevent the ambient air from warming up the cooling component when the cooling component is brought to temperature. One way of achieving such prevention is insulating any portions of the cooling components which do not need to be exposed to cool the tissue. One exemplary insulative material is an aerogel, which can be disposed on any otherwise exposed surface of the cooling component. In one embodiment, the at least a portion of the cooling component that is coated is the elongated portion of the cooling component. In this case, the elongated portion does not come into contact with tissue, and therefore can be insulated along its length, for example being coated with an aerogel. In one embodiment, the cooling component is directly connected to the cold junction of the thermo-electric device via a first thermal interface material. A thermal interface material (or TIM) refers to any material that is inserted between two components in order to enhance the thermal coupling between them. In one embodiment, the heat extraction system comprises a heat sink. It may be a thermal paste, a thermal adhesive, a thermally conductive pad, a thermal tape, a phase-change material, etc. In one instance, the first thermal interface material may include graphene. Other thermal interface materials (e.g. Graphite) could also be used. In one embodiment, the heat sink is directly connected to a hot junction of the thermo-electric device via a second thermal interface material. The second thermal interface material may be the same as the first thermal interface material, or could be different so as to be more tuned for the thermal bonding between the different materials. In one instance, the second thermal interface material may include graphene. In one embodiment, one of more fastening components extending from the cooling component to the heat sink to apply an inward pressure between the heat sink and the cooling component. It can be Important to provide an inward pressure in the stack between the heat sink and the cooling component, so as to ensure that air gaps do not exist in the stack which would otherwise compromise the thermal properties of the device. By providing pressure-providing devices, in some cases, thermal interface materials and / or adhesives can be removed entirely or minimized (although both can be used in combination if further bonding is required). In one embodiment, the fastening components do not contact the first thermal interface material and / or the second thermal interface material. In one embodiment, the one or more fastening components are arranged such that at least one fastening component is positioned adjacent each edge of the thermo-electric device. In one embodiment, at least two fastening components are positioned adjacent each edge of the thermo-electric device. In one embodiment, the fastening components are insulated with an insulating material and / or comprise an insulating material. Such insulation can be provided to further improve the thermal properties of the device (by prevent heat from conducting through, e.g., metal screws). In one embodiment, the one or more fastening components comprise one or more threaded screws. In one embodiment, wherein the thermo-electric device is connected to the heat sink and to the cooling component by one or more adhesive materials. In cases where adhesives are present to hold the layers in contact with one another, fastening elements can be removed. In one embodiment, the device further comprises one or more fans located at least partially within the housing. The presence of fans can be used to improve the air flow over the exposed surface area of the heat sink, thus providing an improvement to the efficiency of the heat extraction system (thus, keeping the hot junction of the thermo-electric device cooler, and in turn, improving the cooling efficiency). In one embodiment, the handheld cooling device comprises an internal power source. The internal power source refers to an electrical power source (i.e. a source configured to deliver a voltage or a current), and which is internal to the handheld cooling device (i.e. within the housing). It is configured to deliver electrical power to the thermo-electric device. It further may be used to power additional components or peripherals within the device (e.g. a processor, a display, etc.). This display may be an LCD, for example. In one embodiment, the internal power source is a battery. It may be understood that the battery may comprises one or more battery cells, and each of the battery cells may be rechargeable (i.e. secondary cells). In one embodiment, the battery operates with a power of less than or equal to 200W, and wherein the battery has a bounding box volume of less than 1000cm3 and a weight of less than 3kg. In one embodiment, wherein the battery operates with a power of less than 100W, less than 70W, or less than 50W. Due to the thermal efficiencies of the handheld cooling device, a smaller battery can be used to provide the cooling effect, thus leading to a more lightweight and ergonomic cooling device. By removing space in the device typically reserved for a power source, the additional space can be utilized to increase the size of the internal components (e.g. the heat sink), or additional components can be added to the handheld cooling device to add further functionality. In one embodiment, the handheld cooling device is a wireless device during operation. A wireless device refers to a device that can be operated entirely without any additional connections (e.g. electrical wires for power, fluid lines for liquid cooling, etc.). In one embodiment, during operation, the thermo-electric device is configured to cool the cooling component down to a first temperature; wherein the first temperature is less than or equal to 10 degrees Celsius, or less than or equal to 0 degrees Celsius. By being capable of reaching temperatures of below 10 degrees or 0 degrees Celsius, the cooling component can provide an adequate cooling effect to tissue in order to provide an anaesthetic effect to tissue. In one embodiment, the handheld cooling device further comprises a handle attached to the housing, optionally wherein the handle is in a pistol-grip configuration. Such a handle is advantageous for single-handed operation, which is advantageous for improved ergonomics during use. According to a further aspect of the invention, there is provided a heat sink comprising: a heat transfer component comprising a metal and having a first thermal conductivity, wherein the heat transfer component comprises at least one cavity; and at least one thermal insert, each thermal insert configured to be inserted into a corresponding cavity of the at least one cavity, the at least one thermal insert comprising diamond and having a second thermal conductivity which is different from the first thermal conductivity. Provided is a heat sink which provides a high amount of heat dissipation in a small footprint, which makes it light and therefore suitable to be inserted into handheld devices which need to be manipulated by a user. In this context, a heat transfer component refers to a structure having a number of cavities (i.e. empty spaces which can be partially or entirely filled with inserts). The cavities can extend at least partially across a length of the heat transfer component, or can extend across almost the entire length of the heat transfer component. There may be one or more cavities dispersed at different locations within the heat transfer component. The benefit of having diamond elements within the cavities of a metal heat transfer component is that the thermal conductivity can be greatly increased, due to the thermal properties of the diamond, without requiring diamond to form the entire heat sink. This also allows for a lightweight metal (such as aluminium) to form the bulk of the heat transfer component. In one embodiment, the heat transfer component comprises a base and a plurality of extrusions extending from the base. In this case, the extrusions (which may include fins, pins, etc.) are heat dissipating elements for increasing the surface area of the heat sink which is in contact with ambient air. They are defined as any element which extends from a base of the heat transfer component. In one embodiment, the plurality of extrusions comprises a plurality of pins having a prismatic or cylindrical structure, preferably wherein the prismatic structure comprises a rectangular-shaped base. By providing a plurality of pins, the thermal performance can be improved, particularly when air flow is limited to the pins, due to the increased surface area afforded by the plurality of pins. In one embodiment, each of the plurality of pins has a cross-sectional area of between 0.03 and 20 mm2, optionally within 1 to 15 mm2. In one embodiment, each of the plurality of pins has a length of 0.5 mm to 50 mm, and optionally 5mm to 30mm. In one embodiment, the density of the plurality of pins along a length of the heat sink is between 0.02 and 10 pins / mm, and / or wherein the density or the plurality of pins along a width of the heat sink is between 0.2 and 10 pins / mm, and / or wherein the density of the plurality of pins across the area of the heat sink is 0.1 pins / cm2 to 50 pins / cm2. Such parameters of the pins are advantageous because they provide a form factor of a heat sink which is ideal for incorporation within a handheld device and which can provide a necessary heat dissipation function. In one embodiment, the at least one cavity extends into the base. Put another way, there can be one or more cavities in the base of the heat sink, whilst the extrusions (e.g. pins or fins) do not include any cavities. In one embodiment, the at least one thermal insert comprises a metal-diamond composite. A metal-diamond composite may provide the increased thermal conductivity required to improve the thermal properties of the heat sink, whilst being more easily manufacturable and less expensive than a entirely diamond insert. In one embodiment, the second thermal conductivity is higher than first thermal conductivity. In this way, a cheaper metal (but having a lower thermal conductivity) can be used as the heat transfer component, whilst a more expensive material (but having a higher thermal conductivity) can be used to improve the thermal properties. In one embodiment, the first thermal conductivity is in the range of 150 to 500 ^and the second thermal conductivity is in the range of 1000 to 3500 —. It has been found that these ranges of thermal conductivities are particularly advantageous for a lightweight and efficient heat sink capable of being inserted into a handheld device. In one embodiment, the base and / or the plurality of extrusions are formed from aluminium, copper, or brass. In one embodiment, the at least one thermal insert is formed from an aluminium diamond composite, a copper diamond composite, ora brass diamond composite. In one embodiment, a volume fraction of diamond in the heat sink is between 10% and 90%, optionally between 20% and 80%, and further optionally between 30 and 70%. A volume fraction may refer to a total percentage of the actual volume of heat sink which is occupied by diamond (or by a diamond composite). In one embodiment, the at least one thermal insert comprises a plurality of layers, wherein the plurality of layers comprises a top layer, a middle layer, and a bottom layer. In one embodiment, the top layer and the bottom layer are formed from aluminium, copper, or brass and wherein the middle layer is formed from an aluminium diamond composite, a copper diamond composite, ora brass diamond composite. The benefit to such an arrangement is that the top and bottom layers can be provided to reduce the thermal interface between the insert and the base of the heat sink, whilst the middle layer can be adjusted more freely to improve the thermal properties. In one embodiment, the aluminium diamond composite or copper diamond composite comprises carbide coated diamonds. In one embodiment, the carbide coated diamonds are formed via chemical vapour deposition. In one embodiment, the middle layer is formed via chemical vapour deposition so as to bond the aluminium, copper, or brass to the carbide coated diamonds. In one embodiment, the at least one thermal insert occupies 5% to 90% of the total volume of the heat sink. In one embodiment, the at least one thermal insert has a total volume between 0.5 x 105 m3 and 20 x 105 m3, optionally between 1 x 105 m3 and 11 x 105 m3, and further optionally between 5.5 x 10-5 m3 and 7 x 10'5 m3. In one embodiment, a total surface area of the at least one thermal insert is between 0.01 and 0.1 m2, optionally between 0.02 and 0.09 m2, and further optionally between 0.045 and 0.065 m2. In one embodiment, the heat transfer component has a mass between 0.1 kg and 2 kg. In one embodiment, the heat sink has a bounding box volume within a range of 4,000 mm3 to 600,000 mm3, optionally within a range of 12,500 mm3 to 450,000 mm3, or further optionally within a range of 100,000 mm3 to 350,000 mm3. In one embodiment, the heat sink has an actual volume within a range from 4,000mm3 to 122,000mm3, optionally within a range of 10,000 mm3 to 75,000 mm3, or further optionally within a range of 30,000 mm3 to 60,000 mm3. Such parameters of the heat sink are advantageous because they provide a form factor of the heat sink which is ideal for incorporation within a handheld device and which can provide a necessary heat dissipation function. According to a further aspect of the invention, there is provided a device, comprising a heat sink and a cooling device, wherein the cooling device is thermally coupled to the base of the heat sink, the heat sink comprising a heat transfer component comprising a metal and having a first thermal conductivity, wherein the heat transfer component comprises at least one cavity; and at least one thermal insert, each thermal insert configured to be inserted into a corresponding cavity of the at least one cavity, the at least one thermal insert comprising diamond and having a second thermal conductivity which is different from the first thermal conductivity. Such a device has many uses, including, e.g. applying a cooling effect to a piece of tissue to work as a cryogenic anaesthetic, thereby obviating the need for topical or general (pharmaceutical) anaesthetics. In one embodiment, the cooling device comprises a thermo-electric device. A thermo-electric device refers to a device where electric current running through the device can cause the device to provide a heating or cooling effect, and vice versa. It has been shown for the first time that a handheld cooling device capable of cooling a cooling component down to 10 degrees Celsius or lower is possible with the weight and volume parameters. This improvement in efficiency is advantageous because there are clear ergonomic advantages to having a device with certain size and weight parameters, whilst still being able to achieve low temperatures for cooling an object brought into contact with the cooling component. In one embodiment, the heat transfer component is coupled to the thermo-electric device at a plurality of connection points, optionally wherein the connection points are arranged around the periphery of the at least one cavity. These connection points may comprise one or more fastening elements configured to provide an inward pressure between the heat transfer component and the thermo-electric device for the purpose of reducing thermal impedance between these elements. Alternatively or additionally, a thermal adhesive and / or a thermal interface material may also be provided. In one embodiment, the thermo-electric device comprises a Peltier-effect device having a hot plate thermally coupled to the base of the heat transfer component, a cold plate, and an interconnect region between the hot plate and the cold plate. According to a further aspect of the invention, there is provided a handheld cooling device comprising a housing, a handle attached to the housing, and a device comprising a heat sink, and a cooling device, wherein the cooling device comprises a thermo-electric device, and wherein the thermo-electric device comprises a Peltier-effect device. The Peltier-effect device has a hot plate thermally coupled to the base of the heat transfer component, a cold plate, and an interconnect region between the hot plate and the cold plate, and the cold plate of the thermo-electric device is thermally coupled to the cooling component. The heat sink comprises a heat transfer component comprising a metal and having a first thermal conductivity, wherein the heat transfer component comprises at least one cavity; and at least one thermal insert, each thermal insert configured to be inserted into a corresponding cavity of the at least one cavity, the at least one thermal insert comprising diamond and having a second thermal conductivity which is different from the first thermal conductivity. In one embodiment, the handheld cooling device further comprises one or more fans for dissipating heat from the heat transfer component. The presence of fans can be used to improve the air flow over the exposed surface area of the heat sink, thus providing an improvement to the efficiency of the heat extraction system (thus, keeping the hot junction of the thermo-electric device cooler, and in turn, improving the cooling efficiency). In one embodiment, the handheld cooling device further comprises a power source electrically connected to the thermo-electric device, preferably wherein the power source comprises a battery. The internal power source refers to an electrical power source (i.e. a source configured to deliver a voltage or a current), and which is internal to the handheld cooling device (i.e. within the housing). It is configured to deliver electrical power to the thermo-electric device. It further may be used to power additional components or peripherals within the device (e.g. a processor, a display, etc.) It may be understood that the battery may comprises one or more battery cells, and each of the battery cells may be rechargeable (i.e. secondary cells). In one embodiment, the cooling component is configured to be cooled by the thermo-electric device to temperatures below 10 degrees, and optionally below 0 degrees Celsius. By being capable of reaching temperatures of below 10 degrees or 0 degrees Celsius, the cooling component can provide an adequate cooling effect to tissue in order to provide an anaesthetic effect to tissue. According to a further aspect of the invention, there is provided a disposable cover for covering at least a portion of a cooling component of a cooling device, the cooling component being configured to be brought into contact with tissue for the purpose of cooling the tissue, wherein the disposable cover is configured to provide sterility of the at least a portion of the cooling component; wherein the disposable cover comprises a sterile or sterilizable metal or plastic material, and wherein the disposable cover is configured to provide a thermally conductive pathway between the cooling component and the tissue. The cooling device for which this disposable cover is applied may be configured a cooling effect to a piece of tissue to work as a cryogenic anaesthetic, thereby obviating the need for topical or general (pharmaceutical) anaesthetics. The cooling device may have an exposed cooling component (which may, e.g. be made from a conductive material, such as metal, and which is connected to a thermo-electric device). As this cooling component (or a contacting surface area thereof) is configured to be brought into contact with tissue in a clinical setting, it is desirable that a disposable cover can be provided so as to avoid cleaning the cooling component itself between patients so as to maintain sterility. The disposable cover may be sterile and single use (e.g. a new disposable cover is positioned on the cooling component for each application of the cooling device). Alternatively, the disposable cover may be sterilizable (i.e. can be reprocessed and cleaned between each application of the cooling device). In such a sterilizable embodiment, the disposable cover may be sterilized separate from the cooling device. The sterilizing procedure may include applying moist heat, dry heat, radiation, vaporized hydrogen peroxide, application of an acid or gas (e.g. ethylene oxide, or chlorine dioxide), which may neutralize any microorganisms which could be present on the cover post application to tissue. That is, a sterilizable cover may be one which is heat stable and / or corrosion resistant and therefore able to undergo any of the above procedures. Of course, since the treatment provided by the cooling device is to apply a cold temperature to tissue, the disposable cover must be suitable for thermal conduction between the tissue and the cooling component, without negatively impacting the thermal performance of the device. In one embodiment, the thermally conductive pathway has a thermal resistance within a range of 1.3 x 10'5 K / Wto 8000 K / W. It has been shown that a cooling component having these ranges of thermal resistance would adequately work as a thermal interface between the tissue and the cooling component. In one embodiment, the disposable cover has a contacting surface area of 10mm mm2 to 5000 mm2, or optionally of 25mm2 to 2500mm2, the contacting surface area being the surface area which can be brought into contact with the tissue. The disposable cover is configured to cover a contacting surface area of the cooling component, and therefore its size is related to the underlying contacting surface area of the cooling component. In this case, it has been determined that a contacting surface area of 25 to 2500 mm2 can provide an adequate area of tissue cooling, which can be used for an anaesthetic effect in advance of inserting a needle into the tissue. In one embodiment, a thermal interface component, wherein the thermal interface component forms a portion of the thermally conductive pathway. A thermal interface component refers to any component which can enhance thermal coupling. It may include one or more thermal interface materials which can be disposed on or within the disposable cover, ora thermal pad disposed on or within the disposable cover. In one embodiment, the thermal interface component comprises a thermal pad, preferably a compressible thermal pad. A thermal pad may refer to a thermally conductive pad. It may be compressible, i.e. able to be compressed when pressure is applied. Such compression may be advantageous when the thermal pad comes into contact with tissue, as it may reduce any air pockets between the tissue and the disposable cover, thereby improving the thermal properties and reducing the thermal resistance of the cover. In one embodiment, the compressible thermal pad comprises a graphite sheet, a graphene pad, or liquid metal. A graphite or graphene compressible thermal pad will provide a high amount of thermal conductivity without significant thickness or any need for thermal pastes or greases. A liquid metal refers to any metal or metal alloy which is liquid at or near room temperature. Liquid metal alloys are known for high thermal conductivity values, and the presence of a liquid metal (e.g. as a thermal interface material) can further improve the thermal conductivity. The liquid metal may be encapsulated within one or more pockets of the compressible thermal pad. In one embodiment, the disposable cover further comprises a thermally conductive gel, paste, grease, or liquid metal, wherein the thermally conductive gel, paste, grease, or liquid metal forms a portion of the thermally conductive pathway. The thermally conductive gel, paste, grease, or liquid metal may form part of the thermal interface between the cooling component and the tissue. In one embodiment, the gel, paste, grease, or liquid metal can be applied to the interior or exterior surfaces of the disposable cover, so that when the disposable cover is applied to the cooling component, the thermal Interface material reduces the thermal impedance at the junction between the cooling component and the disposable cover, for example. In one embodiment, the disposable cover further comprises one or more breakable compartments containing the thermally conductive gel, paste, or grease, or liquid metal, wherein the one or more breakable compartments are configured, when the disposable cover is applied to the skin, to break and disperse the thermally conductive gel, paste, grease, or liquid metal. In some cases, the disposable cover has breakable compartments, which break when under pressure to release the gel, paste, or grease. In this case the breakable compartments can hold the thermal interface materials secure whilst the disposable cover is being applied, and release them when necessary during treatment of a patient with the cooling device. In one embodiment, the disposable cover may be resterilised for reuse. The sterilizing procedure may include applying moist heat, dry heat, radiation, vaporized hydrogen peroxide, application of an acid or gas (e.g. ethylene oxide, or chlorine dioxide), which may neutralize any microorganisms which could be present on the cover post application to tissue. That is, a sterilizable cover may be one which is heat stable and / or corrosion resistant and therefore able to undergo any of the above procedures. In one embodiment, the disposable cover comprises a mechanism configured to prevent the disposable cover from being reused. In one embodiment, the disposable cover comprises an attachment mechanism configured to releasably attach the disposable cover to the cooling component. In some cases, the attachment mechanism may be a physical connection to the cooling component (e.g. a clip), or it may be an adhesive which may help secure the disposable cover in place. The adhesive may be e.g. a strip of adhesive which can be covered until the disposable cover needs to be applied. In some cases, the attachment mechanism may be a tab of the disposable cover which configured to be bent around a portion of the cooling component, so that the disposable cover is retained on the cooling component in a mechanical fashion. In one embodiment, the attachment mechanism comprises a thermally-conductive adhesive. In some cases, the adhesive itself is thermally conductive to further improve the thermal characteristics between the cooling component and the disposable cover. In one embodiment, the disposable cover comprises a feature configured to leave an indicating mark on the tissue when brought into contact with the tissue. It can be important to indicate to a user of the device where on the patient’s body the tissue has been treated with the cold temperature. Thus, a user of the device can cool the tissue via the cooling component and the disposable cover, remove the device, and have a clear indication of where to inject a needle or administer a vaccination, for example. In one embodiment, the feature configured to leave an indicating mark comprises one or more protrusions or indents in the disposable cover, such that a pattern is formed on the tissue when the disposable cover is brought into contact with the tissue. By having a physical, textured pattern on the exterior of the disposable cover, a corresponding pattern can be transferred to the patient’s skin, without needing to provide any alternative marking. In one embodiment, the feature configured to leave an indicating mark comprises a material configured to be transferred to the tissue, optionally wherein the material comprises an ink. In this case, an ink (or other material) can be transferred from the disposable cover onto the tissue, which means that the design of the disposable cover can be simplified (no textured pattern required), whilst still leaving a clear indication on the patient. In one embodiment, the disposable cover comprises a metal material. By providing a metal within the disposable cover, improved thermal conductance can be achieved, which prevents a loss of efficiency for the cooling device. In one embodiment, the disposable cover is formed by sheet metal stamping or from a current additive manufacturing process, preferably direct metal laser sintering. In one embodiment, the disposable cover comprises a plastic material. According to a further aspect of the invention, there is provided a handheld cooling device comprising: a housing; a thermo-electric device located within the housing; and a cooling component, the cooling component coupled to a cold junction of the thermo-electric device, the cooling component configured to receive a disposable cover. According to a further aspect of the invention, there is provided a kit, comprising a handheld cooling device and a disposable cover. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A depicts a schematic illustration of a thermo-electric device. Figure 1B depicts an illustration of one implementation of a thermo-electric device. Figure 2A depicts a handheld cooling device according to one embodiment of the invention, being applied to tissue to provide an anaesthetic effect. Figure 2B depicts an alternative embodiment of the handheld cooling device, where the cold junction of the thermo-electric device is exposed for direct contact. Figure 2C depicts a handheld cooling device according to a further embodiment of the invention. Figure 3A depicts multiple views of one cooling component suitable for use with a handheld cooling device according to an embodiment of the invention. Figure 3B depicts a cooling component with a disposable cover attached to the distal end of the cooling component. Figure 3C depicts one embodiment of a disposable cover and its attachment to the distal end of the cooling component. Figure 4 depicts a handheld cooling device having an alternative cooling component, which can be applied to a fluid to provide direct cooling to the fluid. Figure 5 depicts a thermal insert for use with a heat sink according to an embodiment of the invention. Figure 6A depicts one embodiment of a heat sink for use with a handheld device. Figure 6B depicts another embodiment of a heat sink, with an alternative arrangement for the thermal insert. Figures 7A and 7B depict multiple views of one exemplary heat transfer component of a heat sink. Figure 8 depicts multiple views of another heat sink, with the placement of the thermal inserts marked. Figure 9 depicts a top-level schematic of the electronics of the device. Figure 10 depicts a handheld cooling device having user interface elements according to one embodiment of the invention. Figures 11A to 11E depict schematics of certain modules for electric control of the device. Figure 11F depicts an assembly of the electronics within an electronics module of the handheld device. Figure 12 depicts exemplary control algorithms for use by the processor to control temperature of the cooling component. Figure 13 depicts an assembled handheld cooling device according to an embodiment of the invention, with a top portion of the housing removed. Figures 14A, 14B, and 14C depict views of the assembled active components within the housing of the handheld cooling device according to one embodiment. Figure 15 depicts an assembled handheld cooling device, according to an embodiment of the invention. Figure 16 depicts an exploded view of the assembled handheld cooling device, according to an embodiment of the invention. Figure 17 depicts a simulation of the thermal properties of a copper nosepiece with different thicknesses. Figure 18 depicts diamond particles at 1293K, 1313K and 1373K with varied particle size from 100-300 pm and Energy Dispersive Spectroscopy intensity for a cu / diamond sample. Figure 19 depicts thermal conductivity of diamond powder particles sized 100-300 pm with copper composite. DETAILED DESCRIPTION Device Overview: A device (otherwise referred to herein as a cooling device, or a handheld cooling device) has been provided which uses cryogenic effects for causing numbness on an injection site right before the injections to allow for pain free injection. This injection site may be a tissue, preferably the surface of an organ (including skin and / or internal organs). This device can be used in clinical setting and is required to be suitable for both children and adults. Additionally, this device is handheld, so that it can be comfortable to use for long durations, cause local anaesthetic effect within a few seconds and lastly be cost effective. Figure 2A depicts one embodiment of a handheld cooling device 10 for providing an anaesthetic effect to tissue. This device 10 includes a heat sink 61, coupled to a TEC 30 via a thermal interface material 55. The TEC is also coupled to a cooling component 41 via a thermal interface material 50. Device 10 comprises a thermo-electric device (otherwise referred to as a thermoelectric cooler [TEC], or a Peltier device). As shown in this figure, the heat sink 61, the TEC 30, and the thermal interface materials are encapsulated entirely within a housing 20. The heat sink 61 comprises a number of pins for increasing the amount of surface area that the heat sink has in contact with ambient air. The cooling component 40 as shown in Figure 2A is connected thermally to the TEC within the housing, but may extend outside of the housing so as to be brought into contact with an object needing cooling, in this instance tissue. In this depicted embodiment, the cooling component 40 may have a generally “L-shaped” profile, although other shapes can similarly be used. The cooling component 40 terminates in a contacting surface area 41, which is the portion of the cooling component which can be brought into contact with the tissue. The shape of this contacting surface area may be, e.g. semi-circular, rectangular, or any shape for the purpose of delivering a cooling effect across a surface to tissue. This device can be brought into contact with a subject’s tissue 200, and the cooling component 41 can be brought to a cryogenic temperature (under 10C or under 0C). Figure 2B depicts an embodiment of a device which is substantially similar to the device shown in Figure 2A, but where a surface of the TEC (a cold junction) is directly exposed to provide a cooling effect (i.e. without a separate cooling component). The device as shown in Figure 2B includes a plurality of fans 80 to further improve the heat extraction capability of the heat sinks 61. It can also be understood that the device shown in Figure 2A can also include a plurality of fans for improving the heat extraction capability of the heat sink. The fans may be positioned at least partially within the surface of the housing. Figure 2C depicts an embodiment of a device which is substantially similar to the device shown in Figure 2A, but incorporating a pistol-grip style handle attached to the housing, and incorporating a plurality of fans, like the ones present in Figure 2B. In some cases, the devices 10 shown in Figures 2A to 2C can be entirely wireless during operation (i.e. performing the cooling effect). Of course, when a battery is present within the wireless device to act as a power supply, an electrical cable can be releasably attached to the wireless device to recharge the battery. The device can include a heat extraction system, such as the heat sink shown in the embodiment of Figure 2A. In one case, a bespoke copper heat sink 61 is provided. This heat sink can be cooled via two high CFM fans, as can be seen in Figure 2B and 2C. For the avoidance of doubt, Figures 2Ato 2C are not drawn to scale, and are merely representative of the layers in the stacked succession (i.e. heat sink, TIM, TEC, TIM, and cooling component) which forms the active elements of the device. The asterisks in the figure (*) demonstrate where the contact point is to the cooling component to provide a cooling effect. It is also noted that alternative heat extraction systems (such as those performed with liquid cooling) can be provided in lieu of a heat sink, although systems come as at a cost of reduced wireless operation. In such cases, the handheld device can be configured to receive a cable connecting one or more fluid pipes to the device, for providing active liquid cooling of the electronics. Extensive heat transfer and fluid dynamics consideration had to be done to be able to design the most optimised heatsink in terms of size, weight, and heat dissipation capacity. An electronic circuit may also be present to allow for control of the assembly. The electronic circuit design must take into account size, as the design itself and the components used had to be as optimised as possible both in terms of size and space to fit within a handheld device. In addition, where the cooling device comes into contact with tissue (the contacting surface area of the cooling component), a disposable cover can be applied in some instances so as to provide a sterile barrier between the device and a patient. It is also worth noting that the cooling device can be applied to other applications, anywhere where rapid and localized cooling is required in a remote environment. For example, instead of applying the device to tissue, the device could be used to rapidly cool fluids (e.g. to provide a refrigeration function). For example, Figure 4 depicts an embodiment of a handheld cooling device with a distinct cooling component (i.e. an elongated rod) which can be brought into contact with a fluid. This fluid may be a fluid inside the human body (e.g. blood, or mucus), or it could be an external fluid which needs to be cooled (e.g. a beverage, a chemical solution, etc.). In this case, the cooling component may not include a bend, and may be sufficiently narrow in width so as to allow the cooling component to be inserted into narrow necks of bottles (for cooling a beverage ora chemical solution). As shown in Figure 10, the handheld cooling device may include one or more user interface elements for controlling the device. For example, it may include a display screen 150 for display information to a user (e.g. the current temperature of the cooling component) and for receiving inputs from a user (e.g. to initiate a control algorithm). The display screen may be an LCD and / or may be touch-sensitive to receive user selections based on information presented to the user. In other cases, there may be a separate UI element (one or more buttons, or directional-pads) on the device to allow the user to navigate through menus displayed on the device and select operating parameters for the device (e.g. selecting different control algorithms). It may further include one or more LEDs 155, which for example can indicate that the device has appropriately received power, indicate when the device is charging, indicate when the device is in operation, indicate when the cooling component has been brought to temperature, etc. The handheld cooling device may also include a switch 160, for providing an ability to switch electric power to the electric elements in the device (an ON / OFF switch). Exemplary TEC Design: The TEC of device 10 may comprise a Peltier device, which generates a heat flux at the junction of two different types of materials. The TEC may also be referred to as a Peltier heat pump, solid state refrigerator, or thermoelectric cooler. When operated as a cooler, a voltage is applied across the device, and as a result, a difference in temperature will build up between the two sides. Such a thermo-electric device 30 can be seen in Figures 1A and 1B. A thermoelectric device (or module) may comprise conductors, legs, and a substrate. When an electrical current (e.g. a DC current) flows through the device, heat is transferred from one side of the device to the other, forming a cold junction (i.e. the plate on the side of the TEC which gets cold) and a hot junction (i.e. the plate on the side of the TEC which gets hot). The maximum efficiency of any refrigeration cycle is ultimately limited by the difference between the desired (cold side) and ambient (hot side) temperature (the temperature of the heat sink). The higher the temperature difference, the lower the maximum theoretical efficiency. A single thermoelectric device 30 may comprise at least one n-type semiconductor placed thermally in parallel (but electrically in series) to at least one p-type semiconductor. There may be a plurality of alternating n-type and p-type semiconductors, optionally positioned as alternating pillars of material. There may be a thermally conducting plate on each side, which may be formed of a ceramic material so as to remove the need for a separate insulator. A single thermoelectric device 30 will have two free ends (attached to the two semiconductors at the ends of the device) so that current can flow across the junction of the semiconductors. In this project, a TEC 30 is used for the external skin cooling device as the temperature can be controlled with great precision / repeatability electronically, and the limited size constraints. One of the important considerations, is the required temperature set-point, which with ambient temperature will provide the temperature difference that the TEC must provide; thus, this will provide the cooling power and then the coefficient of performance (COP) can be determined. Thermoelectric device performance can be measured using the Figure of Merit (FOM), where a is Seebeck Coefficient (V / K), k is the thermal conductivity (W / mK) and a is the electrical conductivity (mK / W): Z= a2olk. Dimensionless FOM is given as ZT where T is the absolute temperature in Kelvin, where typical devices have been constrained to ZT =1 but recent improvements has led to ZT >1. A higher ZT value means greater device efficiency from the material. The numerator is defined as power factor where for high ZT value is from high Seebeck Coefficient and Electrical conductivity with low Thermal Conductivity. These parameters result in trade-off in TEC performance; thus, the dependence between parameters result in non-trivial problem to improve ZT. In one instance, Bismuth Telluride has been chosen as the material for the TEC, as at room temperature Bismuth Telluride has a high ZT figure. However, other TEC materials can also be used which provide the desired cooling effect. The schematic in Figure 1 depicts a number of thermocouples depending on the application, with both p-type and n-type semiconductor elements, which are connecting thermally in parallel and electrically in series. These thermocouples are in between two ceramic plates which have high thermal conductivity and low electrical conductivity. The TEC module couples the thermal and electrical effects which together are known as the Thermoelectric Effect; thus, it can act as a thermoelectric heat pump or generator. Exemplary Cooling Component / Nosepiece: Figure 3A depicts one embodiment of a cooling component 40 (also referred to as a nosepiece). In this embodiment, the cooling component comprises a plurality of holes 141, which allow the cooling component to be bolted within a thermal management system such that sufficient pressure is applied to reduce thermal contact resistance between the components (i.e. between the TEC and the cooling component). As can be seen from Figure 3A, the cooling component 40 may have a generally uniform thickness and a L-shaped side profile. The cooling component has a proximal end 40A and a distal end 40B. The proximal end 40A of the cooling component can be thermally coupled to a cold junction of the TEC in the device. The distal end 40B includes a contacting surface area 41 for being brought into contact with tissue. Although the proximal end is generally circular, the proximal end 40A may have any known shape. In some cases, the shape of the proximal end may be designed to match the shape of the TEC module. In other cases, the proximal end shape may have a size which is generally similar in area to the cold junction of the TEC module, although not necessarily the same shape. The fastening elements which pierce the holes 141 in the cooling component may also pierce through corresponding holes in the TEC module, or on a bracket supporting the TEC module. In this instance, the proximal direction refers to the side of the cooling component in contact with the TEC. The distal direction refers to the direction along with the cooling component extends away from the connected TEC (i.e. the unconnected end, which provides a surface for cooling an object). The portion which extends away from the proximal direction (i.e. the portion which contacts the TEC) may be referred to as an elongated portion 40C. For the avoidance of doubt, the length of the cooling component may be considered the distance between the proximal-most point and the distal-most point of the cooling component. The thickness of the cooling component is the height of the cooling component extending away from the TEC when connected. The cooling component shown in Figure 3A includes a plurality of holes 141 arranged in a pattern on the proximal end 40A of the cooling component. These holes can be arranged around the periphery of the proximal end 40A. The plurality of holes 141 can be provided to allow fastening elements to pass through the holes, for the purpose of attaching the cooling component 50 to a TEC. In some instances, each of the plurality of holes has a threaded interior surface, so that each hole can receive a threaded screw or bolt. When a thermal interface material is applied between the cooling component and the TEC, the TIM can be applied on a surface of the distal end 40B, optionally the entire surface excluding covering the holes. In other cases, the TIM can be applied within the area defined by the plurality of holes (i.e. in the center of the distal end of the cooling component). As shown in Figure 3A, there may be a mount for a sensor positioned on the distal end of the cooling component, on a surface opposite the contacting surface area. This mount may be used to mount a temperature sensor 130 (such as an NTC device, or thermocouple) or a sensor for detecting contact 120 between an object and the contacting surface area (such as a conductive sensor or a pressure sensor). Exemplary dimensions for the specific embodiment of the cooling component are provided in Figure 3A. It is of course noted that other shapes of the cooling component are within the scope of the disclosure, and alternatives without any holes are also considered. For example, the cooling component could include no holes and be adhered to the TEC through a thermal adhesive material. Where dimensions are disclosed in Figure 3A, it is noted that these dimensions include ranges within 50-150% of the marked value. An exemplary cooling component is also provided in Figure 3B. This cooling component is substantially similar to the one shown in Figure 3A, although it can take any given size and is not constrained to the dimensions shown in Figure 3A. The cooling component of Figure 3B also depicts a disposable cover 300 which has been releasably attached to the contacting surface area at the distal end of the cooling component. The disposable cover 300 provides a sterile interface between tissue and the cooling components and avoids the need for the device itself to be sterilised between patients. Disposable cover 300 as shown can be made out of a thin metal material (e.g. copper) and adhered through a number of mechanisms. As shown in Figure 3C, the disposable cover may have a shape to entirely cover the distal end of the cooling component, including the contacting surface area. It may have an end configured to wrap around the distal end of the cooling component towards the elongated portion 40C of the cooling component. In some instances, the simple act of bending the metal disposable cover 300 in the way shown in Figure 3C is sufficient to retain the cover onto the cooling component. In other cases, the end which wraps around the cooling component may include an adhesive layer to ensure the cover does not become loose during use. In other cases, an adhesive can be placed within the inner surfaces of the disposable cover, so that the adhesive directly contacts either the contacting surface area or the opposite surface to the contacting surface area. In these cases, the adhesive can be a thermal adhesive so as to ensure appropriate thermal conductivity between the cover and the contacting components. Regardless of whether an adhesive is present, one or more elements may be present in the disposable cover 300 so as to improve the thermal pathway and avoid lossy thermal resistance. In some cases, the cover may include one or more thermal interface materials which can be present on the surface of the cover, or encapsulated within pockets that can burst and release the thermal interface material under pressure. In one embodiment, the cooling component 40 is formed from copper. Copper has a high thermal conductivity value, and thus the heat transfer between the TEC and the tissue can be optimised. Nevertheless, a variety of different materials could be used to form the nosepiece, particularly if it is desired to further reduce the weight of the device. The cooling component can extend away from the TEC with any given geometry, although a specific example of a cooling component is provided below. In other cases, the cooling component and the cold junction of the TEC can be one and the same (i.e. the TEC is applied directly to the object desired to be cooled). The exposed areas of the cooling component can be insulated with aerogel insulation foam, minimizing thermal losses in the assembly and the neck was optimized such that it did not have to be longer than required. The thickness of the part show can be 0.5 mm; however, in further iterations the part can be up to 3 mm thick for improved thermal performance. Figure 17 depicts a simulation in COMSOL Multiphysics of the copper nosepiece with different thicknesses defined in a parametric study of 3 mm and 1 mm respectively. The boundary conditions are the temperature BC at -5 in the TEC square and natural convection heat flux BC around the plate with h = 10 W / m2K and an external temperature of20°C representing ambient which is also defined as the initial temperature. It is evident that the thermal gradient all things being equal, that it is dramatically reduced with an increased thickness on the nosepiece of 3mm. However, if the thickness is too high, the TEC might not be able to provide sufficient heat flux to cool down the nosepiece due to copper’s specific heat capacity; thus, 3 mm was the ideal thickness to avoid this issue and benefit from increased performance. According to one embodiment, the thickness of the cooling component may be in a range from 0.5 to 5mm. The thermal effects can be further improved by covering the nosepiece in aerogel insulation, setting the Qc from the TEC as a BC at and natural convection heat flux BC as the nosepiece is isolated from the fans in the device which is a reasonable assumption. The Qc BC was deduced to be 4.4W as the 22W power supply the TEC is 20% efficient. A stationary solution was conducted and from the cut plane temperature graph in Figure 2.4 below, the aerogel insulation makes a significant difference as there is almost no thermal gradient in the 3 mm plate but significant thermal gradient in the 1 mm plate. The bolts going through the thermal management system assembly may have nylon washers for each component to minimize any heat losses which could significantly affect thermal performance. The bolts were the main component regarding the pressure mount used for this system and to apply the appropriate pressure required for the HITEK STC050-200 silicone-graphene TIM. Exemplary TEC Control: There may be provided a processor (or controller) configured to execute a control algorithm for controlling the TEC. In general, there are two main methods for controller the TEC, one is Pulse Width Modulation (PWM) and second is Direct Current (DC). PWM is a technique that allows for the control of analogue circuit with the digital outputs of a microcontroller. PWM controllers are used in a wide range of applications from power control to communications. For instant, PWM is a common technique for the speed control of electric motors, LED light intensity, ultrasonic baths etc. In essence, PWM is a square wave signal which is unipolar where the time window of 1 (i.e. ON) can be modulated as needed. Using this, the power that is being delivered to the load will be controller using a microcontroller. A PWM signal may be defined by its signal amplitude, its period (T), its on-time (M), and its off-time (S). The PWM signal will have a duty cycle as defined by M / T (I.e. the percentage of the time during a single cycle that the signal is on). Depending on the output of the power supply the amplitude is usually fixed by the logic 1 of the microcontroller. The frequency of the signal is purely application dependant and will require tuning depending on the application. The duty cycle is represented by the ratio of the ON time to the period of the signal and is denoted as D (i.e. D = M / T. D) which can range from 0 to 1 or 0% to 100%. Duty cycle is used for controlling the power supplied to the load. A PWM signal can be provided to simplify the electronics, as the TEC can be driven directly from the output of a processor / microcontroller. Alternatively, another method for controller TEC modules is applying direct current to the elements and regulating their power directly using the current that is supplied to them. In one case, the current can be directly supplied to the TEC from a DC power source, for example when a user turns power on to the device (with, e.g. a manual switch, or any means for connecting a power supply to the TEC). In other cases, the current can be applied in response to a control algorithm, which is initiated by the processor. In some instances, the processor can switch the power supply into connection with the TEC, so that a DC current is configured to flow through the TEC. Comparing these two control mechanisms, in the case of constant current the temp difference between the two sides of the TEC is around 8 times higher than when using PWM current, therefore, using direct current has been proven to be over 39% more efficient then PWM current. Thus, it is preferable to use a direct current driving method due to the increased thermal properties of the device. Exemplary Thermal Interface Materials'. The heat sink, can be thermally coupled to the thermo-electric device via a thermal interface material (TIM) - i.e. a first interface. In addition, the cooling component can be thermally coupled the thermo-electric device via a TIM - i.e. a second interface. These TIMs in each of the interfaces can be the same material, or they can be different materials. TIMs are important as the thermal conductivity of air is ideal for insulation but not conduction, as a result TIMs are selected from materials of high thermal conductivity to fill up the air voids and allow for enhanced thermal management. A first TIM may therefore form a thermal interface between the hot junction of the TEC (which may be a ceramic plate) and a heat extraction system (which in the case of a heat sink, may comprise a metal). Similarly, a second TIM may therefore form a thermal interface between the cold junction of the TEC (which may be a ceramic plate) and a cooling component (which may be formed from metal, e.g. copper or aluminium). Layers of these first and second TIMs can be depicted in Figures 2A to 2C. A suitable TIM material may have the following parameters i) thermal conductivity, ii) wetting characteristics, iii) heat spreading ability, iv) conformity, v) coefficient of thermal expansion (CTE), vi) thermal cycling durability, vii) ease of application and price, viii) compressibility, ix) density, x) electrical conductivity, xl) compatibility with materials. For modelling the thermal contact resistance with applications of TIM the following Equation can be used with the assumption of 1D steady-state heat transfer: Rt= LkA, where K is thermal conductivity of the TIM, L is the distance along the heat flow and Rt is the thermal resistance and A is the area perpendicular to the flow. Thermal resistance is defined as the resistance of a material to the flow of heat, similarly to electronic circuits, a first order model for thermal management systems can be derived from a system of parallel or series resistances. For taking into account the thermal resistance of the interface it is required to calculate the bulk thermal resistance which is derived from the thermal properties of the TIM and the thermal contact resistance between the two surfaces and the TIM; this is known as thermal impedance and is derived based on the following equation: e=RMaterial + RContact, where R-Material is the bulk material resistance and R-contact is the thermal contact resistance from the contact surfaces and © is known as the thermal impedance. Consequently, this parameter needs to be minimised for optimal performance. Two other improvements that can significantly help this issue is addressing clamping pressure and surface roughness, a smooth surface allows for more contact area and a high clamping pressure will increase the conformity between the contact surfaces and the TIM. In order for the assumption of 1D heat transfer to remain valid, it is important that the TIM has acceptable heat spreading capability to maintain minimal thermal gradient in the x-y plane and reduce any hot spots. It is important to make sure the clamping pressure does not exceed the limitations of the TIM. While adjusting the pressure on the TIM, it is important to take note of the CTE of the material as exerting too much stress can damage the component if the expansion is too high. Lastly, it is desirable for the TIM to have low electrical conductivity to minimise the risk of electrical shorts. In one example, the TIM (used for one or both of the interfaces) is Graphene which has superior performance than Graphite and it is more conformable which allows for easier assembly and application ofclamping pressure. Graphene is a 2D material which is made of a single layer of graphite; the carbon-carbon bond in Graphene is 0.142nm which is significantly lower than 0.344nm in graphite. Graphene is often manufactured by mechanical splitting of Graphite using a diamond tip in addition to a CVD process and plasma exfoliation from natural Graphite. Graphene is effectively a single layer of Graphite and for the commercial applications it would have many of these single layers. As a result, this is referred to as multi-layer Graphene that can have different thickness depending on the application. Graphene could have a high thermal conductivity of upto 3080-5300 W / m.K, in x-y plane and due to electron mobility very high electrical conductivity of up to 105 cm2 / Vs and a corresponding low resistivity of 10-8 Qm. Graphene is also desirable for its strong mechanical properties and low CTE. It is also noted that in some instances, the thermal interface material can be removed, particularly where sufficient pressure can be applied so as to limit any pockets of air between adjacent layers in a stack. Exemplary Heat Extraction Systems: In some embodiments, a handheld cooling device can include a heat extraction system for removing heat from a thermo-electric device. In some cases, this heat extraction system may comprise a heat sink, which can be thermally coupled to the thermo-electric device (e.g. the hot junction of the TEC). A heat sink according to the present invention has been provided, which can provide the necessary heat extraction properties in a small footprint suitable for a handheld device. It may also be understood that the specific heat sink can be used for other heat extraction purposes (e.g. for cooling electronics). Use of a small heatsink is ideal in the handheld device application as it minimise size, cost and weight (and therefore improves ergonomics and performance of the device). The general purpose of the heat sink is that instead of a single block of metal with less than desired thermal conductivity forming the entirety of a heat sink, at least some portions of this heat sink can be replaced with diamond to bring the average thermal conductivity up. These portions can constitute inserts, and the property of adjusting thermal properties of a heat sink can be implemented with inserts in any shape and form. Figure 5 depicts an exemplary thermal insert 65 that can be used with (i.e. inserted into a cavity of) a heat sink 61 according to the present invention. This thermal insert includes a top layer 66, a middle layer 67, and a bottom layer 68. The top layer 66 and bottom layer 68 may each be formed from or comprise a metal, such as copper, aluminium, or brass. In some embodiments, the metal of the top layer is the same as the metal of the bottom layer. In some embodiments, the metal of the top layer and / or the metal layer of the bottom layer is identical to the metal chosen for the heat transfer component 62 (the portion of the heat sink into which the thermal insert 65 is inserted into). The purpose of this matching is to provide improved thermal transfer characteristics between the heat transfer component and the thermal insert. It is desirable to achieve a heat sink performance which is comparable or exceeds the thermal performance of an equivalently sized copper heat sink, but with a lighter heat sink. In one example, the heat sink can include diamond and / or a diamond / copper composite. In another example, the heat sink may comprise an aluminium body that surrounds diamond or diamond -metal composite inserts. Figures 6A and 6B depict exemplary heat sinks 61 having a heat transfer component 62 formed from a base 63 and a plurality of protrusions (pins 64). The pins provide an increased amount of surface area for the heat sink, and may be formed from the same material as the base of the heat sink. In some cases, the pins and the base can be formed out of a unitary piece of material (e.g. by carving the heat sink shape out of a solid block of material by carving out air gaps around the respective pins). In other cases, the pins can be machined separately and bonded or connected thermally to the base of the heat sink. As shown in Figures 6A and 6B, the base may include or more cavities (i.e. spaces within the overall volume of the base that is not occupied by the material of the base). These may be cavities which are carved into one surface of the base of the heat sink, as shown in Figure 6A. The cavity may also be a space which is entirely encapsulated by the base of the heat sink (i.e. an interior space), as shown in Figure 6B. As shown in Figures 6A and 6B, each cavity may be entirely filled by a respective thermal insert 65. Where the cavity / thermal insert is entirely encapsulated, the heat sink base can be manufactured around the thermal insert through, e.g. additive manufacturing. Thus, in this case, the cavity can be considered the space in the base occupied by the thermal insert, even though the thermal insert occupied this space before the base was manufactured. The heat sinks shown in Figure 6A and 6B may include bases and pins formed from aluminium, copper, and / or brass. In one example, there may be a volume ratio (or volume fraction) of aluminium to diamond in the heat sink exceeding 65%. Such a volume ratio refers to the total volume occupied by the diamond with respect to aluminium in the total heat sink. Therefore, when discussing the volume fractions it is relevant in this context as in the heatsink geometry there is a % of aluminium and a % of diamond with respect to the overall volume of the heatsink. In some cases, the volume fraction may be in a range of 15% to 30% diamond and / or 70% to 85% aluminium. Of course, other metals can be used beyond aluminium (e.g. copper, or brass), and a wider range of metal to diamond has also been shown to provide an adequate heat sink (e.g. 10 to 90% volume ratio of metal to diamond). In one embodiment, the inserts 65 can be any shape where they compromise a bottom layer 68 and top layer 66 of aluminium, and the middle layer 67 consists of the carbide coated diamonds. This middle layer may include silicon carbide as it has high thermal conductivity and low acoustic impedance for phonon heat transfer and aluminium. Figures 7A and 7B depict an exemplary heat sink according to one embodiment of the invention. This heat sink has a plurality of holes 141 for fasteners, which can be used to fasten the heat sink to the TEC (and to the cooling component). That is, the plurality of holes on the heat sink can be aligned to a corresponding plurality of holes on each of the TEC (and optionally the cooling) component. This allows a fastener to be inserted through each of the aligned holes to provide a pressure between the heat sink and the TEC. Such a fastening process improves the thermal performance of the device. In some cases, separate fastening components 140 are applied between the heat sink and the TEC from the fastening components 140 applied between the TEC and the cooling component, as shown in Figure 14Aand 14B, for example. As shown in Figures 7A and 7B, the plurality of holes 141 is arranged in a first pattern and penetrate the base of the heat sink (from a first surface which contacts the TEC towards the pins). In some instances, each of the plurality of holes 141 has a threaded interior surface, so that each hole can receive a threaded screw or bolt. When a thermal interface material is applied between the heat sink and the TEC, the TIM can be applied on a surface of the base of the heat sink, optionally the entire surface excluding covering the holes. In other cases, the TIM can be applied within the area defined by the plurality of holes (i.e. in the center of the rectangular shape pattern of holes on the base). A thermal insert can be positioned in the base and within the shape defined by the plurality of holes of the heat sink. Figure 8 depicts an alternative heat sink having a different pattern of holes for fastening the heat sink to the TEC. As shown, there are two generally-rectangular shaped patterns of holes on the base of the heat sink, one on either side of the base. It is noted that any number of patterns could be provided to provide adequate pressure between the heat sink and the TEC. In this case, two thermal inserts 65 are provided, each positioned within a respective rectangular-shaped hole pattern. When a thermal interface material is applied between the heat sink and the TEC, the TIM can be applied on a surface of the base, optionally the entire surface excluding covering the holes. In other cases, the TIM can be applied within the area defined by the plurality of holes (i.e. in each within the two rectangular shaped pattern of holes). Exemplary dimensions for the specific embodiments of the heat sink are provided in Figures 7A and 8. It is of course noted that other shapes of the heat sink are within the scope of the disclosure, and alternatives without any holes are also considered. For example, the heat sink could include no holes and be adhered to the TEC through a thermal adhesive material. Where dimensions are disclosed in Figure 3, it is noted that these dimensions include ranges within 50-150% of the marked value. In some embodiments, the heatsink can include a plurality of pins. The pin-style heatsink allows the surface area to be maximized given the respective performance constraints. In one case, the pin heatsink consists of 392 in-line pins as the airflow is in the reverse impinged direction, where the airflow leaves the device upwards. Of course, any number of in-line pins could be provided (e.g. 50 to 1000) on the heat sink. It is noted that staggered pins may not cause a significant difference as a result of the orientation of the airflow. If the airflow was from the side of the heatsink, then staggered pins would be optimal as for ideal heat transfer, the streamlines must continue onto the next row of pins instead of the separation region behind the pin which would reduce heat transfer performance. Furthermore, there is a trade-off between the optimization between surface area and heatsink staggered pin design as the space constraint is limited. In one example, the porosity of this heatsink (if pins are considered as the porous regions) can be around 0.65, where the volume of the fluid is around 50973.61 mm3 and pin volume 28058.59 mm3 respectively. The porosity is the total void volume divided by total volume of solid matrix and void volume. As this is a forced convection application, a larger porosity would reduce surface area and thus heat transfer despite in natural convection application a higher porosity is favourable as it deduces the performance of geometry to allow flow of fluid through heatsink. As porosity increases, so does the permeability which would improve the convective heat transfer as porosity is greater than 0.5 which means it is within the exponential region with respect to the relation between porosity and permeability. A porosity less than this value may not be beneficial for convective heat transfer. Furthermore, the pumping work determined from pressure loss and flow rate to push the air through a heatsink is high at low porosity and reduces as porosity increases; therefore, as the porosity is not low the airflow will not need to significant work to flow through the pin heatsink. Additionally, the Figure Of Merit (FOM) with respect to the porosity exponentially increases with the porosity along with the COP which correlates with the pumping work reducing at higher porosity values. At significant airflow velocities such as this application, the COP decreases dramatically which is important to consider as natural convection is not possible for the high demands that the TEC places on the thermal management system. In one example, the dimensions of the pin heatsink can be 120 x 74 x 12.7 mm with a pin height of 8.9 mm and base thickness of 3.8 mm, resulting in a total surface area of 54820.16 mm3. It should be understood that the dimensions above can be adjusted within 50-150% of the exemplary values. The material of the pins is pure copper C110 which is 99.9% oxygen-free copper with a thermal conductivity of 386 W / mK. Another heatsink from aluminium 1075 was CNC’d with the same specifications which has a thermal conducitvity of 150 W / mK. The spacing of each pin from its centre is 4.7 mm which is a good trade-off between maximizing surface area and stagnation flow, if there is not enough spacing for air to get through without it being affected by the stagnated flow; thus, the channel width is 1.5 mm. The pin heatsink is more robust than the plate heatsink as it dissipates more heat per unit area and has omnidirectional performance; thus both ideal for size limitation and orientation of handheld device. Again, it should be understood that the dimensions above can be adjusted within 50-150% of the exemplary values. Alternative heat extraction systems have also been considered, including those that include an active cooling element (such as via liquid cooling). In such instances, flowing liquid can be pumped over the hot junction of the TEC so as to extract heat and transfer heat away from the TEC. In such cases, the device may not be an entirely wireless device (but still may be manipulatable as a handheld device), since it may be necessary to include tubing for the liquid cooling system. Exemplary Electronics: The main objective of the circuit design of this assembly is to be able to stabilise the system within the power range of the TEC and control the cold site temperature of the module and maintain it within a specified range. There are multiple parts that may be connected to this circuit such as the cooling fan, TEC element, NTCs, batteries and LED indicators, and all these elements may be controlled by the code that is uploaded onto memory within the circuit. A top-level schematic of the elements in the electronics of the device can be seen in Figure 9. As shown in this figure, a TEC 30 is provided to provide a temperature differential across its cold and hot junctions when electric power is applied to the device by control circuitry 105. The control circuitry can receive power from a battery 71, and / or control the power delivery from the battery 71 to the TEC 30. The battery 71 in the device is also configured to power the other electrical elements in the claim (e.g. the processor 100), although this connection is not explicitly shown. The processor 100 is configured to communicate with a memory 110 (which may be a separate memory chip, or be memory within processor 100) for controlling the TEC and any necessary control circuitry 105. The processor may receive signals from a temperature sensor 130 and / or one or more additional sensors 120 for determining contact of a cooling component attached to the TEC with an object (e.g. tissue). The processor may receive these signals either directly or via electronics in the control circuitry. The control circuitry of the handheld device may include a power unit, a negative temperature coefficient circuit, a fan controller unit, a microcontroller circuit, and a TEC controller unit. Such electric control modules are shown in Figures 11A to 11E. As shown in Figure 11 A, an exemplary power circuit can include two connectors in parallel, one of which is connected to the charging socket to charge the device. The connector J7 is used in series with the battery socket to connect the power switch of the circuit. The “12V” label after J7 is the 12 V supply power that all the elements that require 12 V supply in the circuit are connected to it. Of course, other voltage supplies and batteries can be used other than a 12V supply. In some cases, the voltage of the battery can be measured by the processing unit of the circuit. The microcontroller used in this circuit is an ATMEGA8 from the AVR family that has a voltage level of 5V. The task of identifying and measuring the battery voltage can be done by the ADC convertor element of this microcontroller. The sensors may be used to provide information to the processor for initiating a control algorithm. Different temperature graphs associated with alternative control algorithms can be seen in Figure 12. In the first (top) graph of Figure 12, the cooling component is kept at a first temperature (which may be room temperature [device off] or another initial temperature which is warmer than the final temperature [e.g. 15 degrees Celsius]) before the cooling contact is brought into contact with tissue. Once this point of contact is detected, the processor can initiate a control algorithm (by turning on the TEC, adjusting the set point of the TEC, adjusting the signals delivered to the TEC, etc) to bring the temperature on the cooling component down to the desired temperature (ideally below 0 degrees Celsius). Thus, when a temperature sensor (such as an NTC) is present and attached to the cooling component, this component can be used in the feedback loop of the control circuitry to achieve the desired set point. The benefit of keeping the cooling component at a warmer temperature and gradually lowering the temperature only when contact to the patient is made is that patient comfort can be increased (as they are not instantly exposed to a very cold tip upon contact). In contrast, in the second (bottom) graph of Figure 12, it is also possible to bring the cooling component to a desired temperature in advance of being brought into contact with tissue. In this case, whilst it may result in more initial patient discomfort, it may be possible to expedite the overall time required to achieve the anaesthetic effect. As shown, when applied to human tissue, the temperature at the cooling component will shortly be brough to a higher temperature due to contact with warmer tissue. However, the cooling component can be brought back to the necessary temperature as shown. However, when the highest voltage level of a microcontroller (e.g. 5 V) differs from the voltage of the battery (e.g. 12V) it is required to supply a reduced voltage from the battery’s 12V to it using a potential divider circuit. In the circuit schematic in Figure 11A the elements of the potential divider circuit are R16 and R17 and the “battvoltage” connection point specifies the point of connection to the ADC of the ATMEGA8. Exemplary resistance values having a certain ratio are provided, although other values could equivalently be chosen so as to provide an appropriate value to the ADC of the microcontroller. A diode can also be provided to prevent damage to the circuit due to reverse polarity connection of the power supply or batteries to the circuit. This diode would prevent power supply to the logical and control parts of the circuit in a reverse polarity connection. The diode shown in the Figure 11A is a 1N4007 diode and is labelled D1. It is necessary that the processing unit of the circuit had a constant voltage supply so that the circuit can function without any problems. The ATMEGA8 required 5V power supply and since the batteries of the circuit can provide a voltage between 11.1 to 12.6, a 7805 regulator was chosen. A voltage regulator can also be provided to supply a constant voltage at its output regardless of the fluctuation and the value of its input. This regulator can supply, e.g., from 5V to 35V at its input and get a constant value of 5V at the output. Of course alternative regulators can be provided to take different input voltages and output a regulated voltage at the output, for supply to the microcontroller. Due to limited current supply of the regulator and the elements that will be supplied via it, the voltage regulator element must be carefully selected. In this circuit design the maximum current output required from the 7805 output is around 20mA. With this current and voltage rating the best choice of voltage regulator is a 7805 with SOT-80 package which minimises both cost and space and has an output current of up to 100 mA. Since the process of switching electronic devices off and on can cause noise as well as current and voltage surge, capacitors can be used in both the input and the output of the regulator (i.e.CI, C2 and C3). This was done to prevent voltage ripple in the output of the voltage regulator in the event of any noise, current surge when switching on the fans and TEC. This would allow for optimal supply of the microcontroller. An LED (D2) can be used as a light indicator for indicating sufficient voltage to power the logical parts of the circuit. Since the operating voltage of this LED can be lower than the supply voltage (e.g. 2V), a resistor can be used in series with this diode to prevent the supply of excessive voltage and current. It is worth noting that the nominal current for all the indicators in the circuit can be low (e.g. 10mA); however, the intensity of light is not important as they are only used as indicators, the resistance in series with them has been selected in a way to minimize the current draw (e.g. no more than 3mA). This decision serves two purposes, i) it minimise the load on the voltage regulator and ii) increases the efficiency in battery usage. Of course, whilst a specific power circuit implementation has been described, it is noted that other implementations for providing voltage regulation functions and charging capabilities to power all of the necessary devices could similarly be used, with or without any one of the specific elements described above. Figure 11B depicts an NTC circuit, which can be used to detect the temperature of the cooling component in the device. Thermistors are passive devices and their resistance changes according to the change in temperature. For operating NTCs, there needs to be a constant voltage applied across the resistance and NTC circuit and the output is measured across the NTC. In one embodiment, the circuit can include a 20kOhm NTC and a 20kOhm resistor. At the baseline temp, of 25 °C, the voltage may therefore be half the voltage supply. As the temp, of the NTC changes, so does its resistance and the output voltage, and by measuring the output voltage and knowing the characteristics of the NTC can deduce the temperature. In this circuit, J3 is a 6pin connector for connecting 3 NTCs, and as shown in Figure [3.4] 100nF capacitors are used to stop any potential noise on the NTC signal. The labels, “ntcair”, “ntcheatsink” and “ntcneck” are connected to the ADC convertor of the ATMEGA8. Furthermore, it is worth mentioning that all the thermistors used in the circuit are of 10kOhm resistance. Figure 11C depicts a fan controller circuit. The device according to an embodiment of the invention may use one or more (e.g. 2 fans) having a certain voltage and current input (e.g. 12V and nominal current of 250 mA), which means they require a certain power supply (e.g. 12V and 500mA in total). The speed of the fans can be controlled via a circuit which allows the microcontroller to control the fan speed. This is due to the fact that the microcontroller can output logical signals and to use these signals for controlling different instruments it is required to have a driving circuit. Considering the voltage and current requirement of the fans, the following circuit in Figure 11C was designed. The connection point of this fan to the circuit is the J5 connector which has a pin connected to a voltage supply and another pin connected to a switch (e.g. a BJT transistor). Therefore, one pin of the fan is always connected to a voltage supply and the switch controls the voltage of the fan based on the signal received from the microcontroller (e.g. a PWM signal). Ultimately, the switch in this circuit can receive a signal from the microcontroller and be used to control power to the fan. Until a signal is supplied to the “fanpwm” in the circuit the fans will not switch as the base-emitter voltage of the transistor would be 0V. With the supply of5V, for example, to the “fanpwm”, the base-emitter voltage reaches 0.7 and the transistor switched and allows current to pass which causes the fans to turn on. However, the voltage of the fans is controlled with a PWM signal rather than a continuous 5V signal. Using PWM technique would allow to use the digital signal of a microcontroller to control and analog device such as a fan. In PWM signal, voltage is being applied and then removed from the device (i.e. 1 and 0), this is done in high frequency and for different durations which results in an analog like signal. This works particularly well with fans as due to the momentum of the motor and the propeller at 0 intervals the fans does not stop completely. Ultimately, the device that is controlled with PWM will respond as the average of all the pulses, the target voltage then is possible to be a s-s voltage or dynamic. A diode (D8) may be present as a flyback diode to supress the effects of inductive loads of the fans when the transistors are switching off. An exemplary transistor for this application would be one that can supply the current required by the fans as well as being as small as possible to accommodate the shortage of space. The SS8050 transistor is a BJT that is very cheap and is available in the SOT323 package size which is very economical in terms of size. This small size transistor can sustain up to 1.5A and can driver devices of up to 25 V which make it an ideal component for the implementation. Of course, other transistors or switches can similarly be implemented (e.g. MOSFET, IGBT, etc.). Figure 11D depicts the circuit elements and connections for the microcontroller (or processor) unit. This unit of the circuit provides the brain and the intelligence of the circuit. It may comprise an internal memory or be communicably coupled to an external memory. The microcontroller can controls all parts of the circuit and requires different facilities. First of all, the microcontroller can have an ADC convertor to allow it to assess the battery voltage and the current supplied to the TEC and measuring temperature using NTC. In addition, the microcontroller can generate output signals (e.g. PWM signals) to supply current to the TEC (optionally via one or more amplifiers, including op amps). In addition, the microcontroller can include generic inputs and outputs for controlling a user interface (e.g. LED indicators). In one example, the ATMEGA8 microcontroller from the AVR family has been selected to provide the above functionality. This is microcontroller is an 8-bit controller that is built based on AVR RISC architecture. With this microcontroller, there not a lot of components that are required for running it and with relatively few parts the microcontroller can be setup. As the use environment of the device is unknown and it could potentially be a high noise environment, it is essential that the reset, the AREF and AVCC pins are protected from noise. Figure 11E depicts an exemplary TEC controller unit. This controller controls the current supplied to the TEC based on the signal of the microcontroller. Due to the fact that current is directly controlled the circuit does not use a switching technique or PWM, power dissipation may be quite high in the circuit, and it may dissipate a lot of heat. A PWM protocol for the controller could be implemented which is considerably simplerand far easier to implement and will thus not cause such high amount of heat loss. However, the physics of TEC modules and their dynamics do not allow forthat, as these modules are essentially heat pumps and tuning them on and off is incredibly inefficient. With the above in mind, this circuit is made of two major parts, i) the unit that sets the current of the TEC based on a DC voltage signals, ii) the second part is one that converts the PWM signal from the microcontroller to a DC voltage signal. The control of TEC current using a DC voltage is done by using an op-amp and connecting the negative feedback to a shunt resistorthat is connect to MOSFET via the N channel. The output of the amplifier is then connected to the MOSFET gate. This was done such that it can easily control the current of the TEC by supplying a DC signal voltage to the op-amp. In this circuit the unit that controls the current is the MOSFET that receives its gate signal from the op-amp. The next challenge was to prepare a DC signal to be applied to this circuit to control the current; and since the microcontroller does not have a variable output signal and auxiliary circuit is required to convert PWM signal to DC. Since the TEC controller circuit uses two op-amps, in one example the LM358 device has been selected. This device is also provided in SMD packages, is cost effective and has two op-amp built inside. Since the MOSFET in this circuit needs to transfer a lot of power and is used in a wide voltage range, the selection of suitable MOSFET is a very sensitive and important task. The main objective is to be able to control a TEC module that is connected to a DC supply (e.g. 12V) and is required to control its current in the range of currents (e.g. 0 to 4.5 A) using the MOSFET. The first important point to consider is that the heat generated by the MOSFET is quite significant, therefore, the MOSFET should be solderable on a heat dissipator (e.g. a copper heat dissipator). If the heat generated in the MOSFET is not sufficiently dissipated, with every increment in the temperature of the component the efficiency drops up to a point where the MOSFET bums out. Additionally, in certain operation points the MOSFET is required to sustain up to 40W of power which is quite significant. After extensive research and numerous experiments, the IRF064N was selected. Figure 11F depicts an electrical assembly having a battery 71 within an enclosure 72 for containing the electrical circuitry depicted in Figures 11A to 11E. There may be conductive end-plates attached to either side of the battery for delivering power to the rest of the circuit, along with an electronics enclosure which is insulated and prevents electrical signals from coming into contact with the remainder of the device. Exemplary Assembly and Housing-. Figure 13 depicts an exemplary assembly of the device, with the top portion of the housing removed to show the heat sink and fan elements. Figure 15 then depicts the same device with the top portion of the housing installed. The assembly of the device may comprise a sandwich assembly (i.e. a stacked assembly of the heat sink 61, thermo-electric device 30, and cooling component / nosepiece 40, along with intervening thermal interface materials 50, 65). In some cases, the sandwich assembly may be highly pressurized (e.g. with fastening elements, such as screws or bolts) up to a point where excessive force was required to further fasten the fastening elements. The surface of the cold plate of the thermo-electric device may be insulated from screws coming from the heatsink via PLA and rubber washers fastened on top of one another for improved thermal resistance. There may be provided a housing 20, configured to encapsulate the sandwich assembly and any electronics. The cooling component may be configured to extend out from the housing, or alternatively, the cold junction of the thermo-electric device may be exposed through a gap in the housing for direct application to an object. The housing may be formed out of an electrically and thermally insulative material, such as plastic, which can be comfortably held by the user of the device. The housing can prevent structural damage to the components within the housing (e.g. preventing damage to the sensitive pins of the heat sink or the TEC) as well as prevent any electrical connections from being exposed to a user. When fans 80 are present in the device, they may be entirely encapsulated within the housing (with gaps for airflow present in a region above the fans), or the fans may from one of the side surfaces of the housing (thus, being at least partially exposed). Figures 14A to 14C depict views of the active elements of the handheld cooling device, which includes the TEC 30, the cooling component 40, the heat sink 61, the electronics enclosure 72 (which includes battery 71 and the control circuitry 105) and fans 80. The heat sink is coupled to the TEC and to the fans via fastening components 140. This structure provides an advantage to thermal performance of the device, which enables it to achieve the necessary temperatures of 10C or less under minimum power draw from a battery. The thermal interface materials 50 and 55 can be seen in Figures 14B and 14C, to provide an interface between the TEC and the cooling component and heat sink respectively. The housing may include one or more duct channels aligned with the heat sink pins which would allow the suction of air into the heatsink and then out through the fans. These duct channels may be provided on the sides of the housing and can be seen in Figure 15 around the periphery of the top portion of the housing. Exemplary elements of the housing in an exploded view configuration can also be seen in Figure 16. As shown, the housing can comprise a number of constituent parts (a top portion, a bottom portion) for encapsulating the active elements of the device, as shown in Figures 14A to 14C. A handle is also attached to the housing for ease in ergonomic control by a user. Additional Technical Detail related to Materials of Metal-Diamond'. From the literature it is clear that the thermal conductivity (k) of diamond / copper composites is significantly lower than that of solely copper as it does not wet diamond since it is a non-carbide forming material hence has little affinity to carbon (which is important when a carbon-based thermal interface material, such as Graphene is used). Therefore, resistance at a thermal interface will be significant. This can be reduced by alloying the copper with minor amounts of carbide (B, Ti, Cr, W) during hot pressing and metal infiltration. Consequently, carbide can be added to increase wettability of aluminium and carbon affinity, along with coating the diamond powder surface with a carbide. Spark Plasma Sintering (SPS) can be used to create the diamond-copper composite, where the oxygen-free copper has particle size of 5-10 pm in matrix and reinforcement was MDB8 type diamond powder with nitrogen content of 200ppm from Henan Heng Xiang Diamond co Ltd. Carbide can also be added to the diamond surface at high temperatures when mixing the diamond powder with the composite powder of copper and carbide, where the composition was cu-5 wt.% W. The diamond can be placed in a vacuum induced furnace for the carbide coating at 1273-1373 K in graphite crucible for 20-80 min under hydrogen atmosphere to avoid oxidation. After the diamond powder is cooled, the remaining copper and carbide can be removed via a sieve. This pre-treatment method can solve the Interface resistance problem such that diamond Is compounded directly to the copper that is mixed with carbide. The diamond powder can be ultrasonically cleaned in alcohol, dried and stored in a desiccator, where it is mixed with copper to create the diamond / copper composite. Density can be measured through Archimedes Law, Microstructure analysed using SEM (FEI Sirion-200) and thermal conductivity can be measured by Xenon pyrometry with Netzsch LFA457 equipment Laser Flash Approach. As shown in Figure 18, the surface morphology at 1293 K for diamond is evenly covered for grain sizes less than 200nm. The Energy Dispersive Spectroscopy (EDS) shows high tungsten and copper content, where the continuous surface layer consists of tungsten and carbon, whilst the outer layer is of copper and tungsten. From this it is evident that the tungsten bonds with the carbon from the diamond and then it bonds to the copper on the outer surface; thus, a carbide is important as an interface material. At 1373 K, the interface of the 200 pm diamond there is a rupture at the elevated temperature due to residual stress to the different material GTE when diamond is cooled or heated. The interfacial layer of tungsten carbide can reduce thermal stress of copper / diamond in the interface but the process of melting / solidification causing compressive / tensile stress is what leads to rupture within the interfacial bond. When comparing treated and untreated diamond, where weak interfacial bonding is observed in the untreated and good interfacial adhesion is observed within the pre-treated diamond powder. The weak interfacial bonding of diamond and copper is due to different CTE when cooling and chemical compositions. To determine the thermal conductivity for a given volume fractions and assuming spherical particles with infinite interfacial thermal conductance is the Maxwell-Eucken equation below. It is observed that a 200pm diamond particle with uniform carbide layer which attains proper copper-diamond bonding contact, results in high thermal conductivity. Furthermore, decrease of k is related to thicker carbide layer which reduces heat transfer performance. At 1373K when the rupture occurs, significant fall in k occurs. Therefore, it is important to consider the thickness of the carbide interface layer on the diamond, as a thick layer results in poor thermal performance. Exemplary thermal conductivities for different diamond sizes 100-300 urn for a fixed volume fraction of 46A copper at different pre-treatment temperatures is provided in Figure 19. When the theoretical thermal conductivity (k) is calculated, it is 90% within the k from the composite which signifies that the bonding of the carbide coated diamond particles and the metal matrix is strong. The conclusion of this paper notes that the pre-treatment temperatures and time of the pre-treatment are critical issues to avoid carbide layer becoming too thick causing increased thermal resistance. There is thermal resistance at 1) diamond / interfacial layer, 2) interfacial layer and 3) interfacial layer / metal interface; hence, tungsten with a k of 121 W / mK is used due to high thermal conductivity to minimize these thermal resistances. The experimental results determined that there is a improvement when the copper matrix is alloyed with a carbide for the MMC of CuCr / diamond composite when compared with pure copper matrix. Without the carbide to form the alloy, the thermal conductivity was measured as 200 W / mK which is due to high thermal boundary resistance and a k of 600 W / mK was measured for CuCr / diamond and a CTE of 9 x 10-6. The boundary conductance for Cu / diamond was 0.5 x 10? W / m2K and for CuCr / diamond it was 3.5 x 10? W / m2K respectively which coincides with the k of each composite. The overall maximum bulk k is 740 W / mK and max boundary conductance is 10x10? W / m2K meaning it can be further improved. The k and boundary conductance is explained by the absence of chemical affinity between copper and diamond. There is good carbide formation on all diamond faces in the CuCr / diamond MMC in contrast to AI4C3 in Aluminium / diamond MMC which will be explored in the next paper. There is an emphasis that the rate of carbide growth is essential to maximize thermal conductance between the boundary; therefore, the interface layer should be of low thickness and not completely covered to hinder the thermal conductivity performance of diamond. Aluminium / diamond MMC will now be discussed, and gas pressure infiltration and mechanically assisted infiltration also known as squeeze casting are compared. The reinforcement material is typically inside the die whilst the matrix material is in molten state and poured into the die, which is then compressed to combine both materials into desired MMC; additionally, the die is shaken to ensure homogeneity in the MMC. Aluminium is ideal metal in this process as easy to melt, shape and will not melt the casting due to the melting point being below that of the graphite coating in the die. The benefits of squeeze casting method is fine details, high quality, low shrinking defects, high production rate and less pressure compared to forging; however, it has a high tooling cost, no tooling flexibility, accurate control required, and large scale production required to justify the overall cost. If the semiconductor component and Aluminium / diamond heatsink is soldered, mismatch of CTE must be avoided to mitigate solder-joint failure; thus, similar CTE and high k a priority for interface solder essential. The reason why MMC from diamond is more feasible for thermal management applications is the bulk manufacturing of synthetic diamonds made possible from High Temperature High Pressure (HTHP) which has made them more affordable. The nitrogen content in these diamonds is classified into different categories according to ppm which affects k, and it is ideal in aluminium as it reduces CTE within semiconductor range whilst increasing k. Performance Results of Device-. At a room temperature of around 24.5 degrees Celsius, it has been shown that the described device can consistently reach sub-zero temperatures with a power not exceeding 35W. As can be seen from these figures, the device took between 11 and 13 seconds to reach sub-zero temperatures. Meanwhile, the heat sink temperature never exceeded 38 degrees Celsius in the same time period. Said temperatures were measured by thermocouples that were attached in testing to the heat sink, to the elongated portion of the cooling component (otherwise referred to as the “neck”) and the contacting surface area of the cooling component (otherwise referred to as the “tip”, or “nose”). The thermocouple may be provided with an NTC device. In a final device, it may not be necessary to include thermocouples on the cooling component directly in some instances, as it can be possible to derive the temperature of the cooling component based on the electrical power consumption and / or the temperature of the heat sink. Alternatively, one or more thermocouples on the cold junction of the TEC or on the cooling component may be included so as to improve control. Time (Minutes:seconds) Current Initial [A] Current Final [A] Voltage [V] Temp [degree C] 00:01:00 0.57 0.43 1 Heatsink=25, Neck=19, Nose=19.5 00:03:00 0.96 0.85 2 Heatsink =26, Neck=14.90, Nose=15.36 00:05:00 1.04 1.28 3 Heatsink =26.94, Neck=10.53, Nose=11.12 00:07:00 1.89 1.77 4 Heatsink =28, Neck=6.14, Nose=6.94 00:09:00 2.30 2.22 5 Heatsink =29.36, Neck=2.94, Nose=3.85 00:11:00 6 Heatsink =31.19, Neck=0.24, Nose=1.31 00:13:00 3.21 3.15 7 Heatsink =33.43, Neck=-1.50, Nose=-0.37 00:15:00 3.75 3.64 8 Heatsink =36, Neck=-3, Nose=-1.81 00:17:00 3.89 8.5 Heatsink =38, Neck=-2.83, Nose=-1.66 As seen from the data in this table, the temperature of both the elongated portion and the contacting surface area were brought quickly down to below 10 degrees in around 7 seconds, and down to below 0 degrees C in around 12-13 seconds, at the stated current values and voltages. Additional Aspects: According to a further aspect of the invention, there is provided: (Aspect 1) A handheld device, comprising: a housing; a thermo-electric device located within the housing; a cooling component thermally coupled to a cold junction of the thermo-electric device; and an internal power source, preferably a battery, configured to provide power to the thermo-electric device, wherein, during operation, the thermo-electric device is configured to cool the cooling component down to a first temperature; and wherein the first temperature is less than or equal to 10 degrees Celsius, wherein the battery operates with a power of less than or equal to 200W. In one embodiment, the battery of this aspect has a bounding box volume of less than 1000cm3 and a weight of less than 3kg. According to a further aspect of the invention, there is provided: (Aspect 2) A handheld device, comprising: a housing; a thermo-electric device located within the housing; a heat sink thermally coupled to a hot junction of the thermo-electric device, the heat sink comprising a plurality of pins, wherein the density of the plurality of pins across the area of the heat sink is 0.1 pins / cm2 to 50 pins / cm2. In one embodiment, the handheld device of this aspect further comprises a cooling component thermally coupled to a cold junction of the thermo-electric device. According to a further aspect of the invention, there is provided: (Aspect 3) A handheld device, comprising: a housing; a thermo-electric device located within the housing; a heat sink thermally coupled to a hot junction of the thermo-electric device, the heat sink comprising a plurality of pins; and one or more fans positioned at least partially within the housing, the one or more fans configured to increase an air flow through the heat sink, wherein a flow rate of the one or more fans at zero static pressure is in a range from 0.1 m3 / min to 10 m3 / min. In one embodiment, the handheld device of this aspect further comprises a cooling component thermally coupled to a cold junction of the thermo-electric device. According to a further aspect of the invention, there is provided: (Aspect 4) A handheld device, comprising: a housing; a thermo-electric device located within the housing; a cooling component thermally coupled to a cold junction of the thermo-electric device; a processor and a memory, the memory storing instructions for a control algorithm, wherein the processor is configured to execute the control algorithm to operate the thermo-electric device, and one or more sensors communicably coupled to the processor, the one or more sensors configured to identify a point of contact between the cooling component and the tissue and / or the fluid, wherein the processor is configured to execute and / or adjust the control algorithm based on the point of contact identified by the one or more sensors. In each of the above further aspects of the invention, the embodiments listed in the summary of the application can also be applied to each of the above devices. Further Comments: The preceding description has been presented with reference to presently disclosed embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. As understood by one of ordinary skill in the art, the drawings are not necessarily to scale and any feature or combinations of features described in any one embodiment may be incorporated into any other embodiments or combined with any other feature(s) of other embodiments, as desired or needed. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope. For all of the above-described devices, it is to be understood that the disclosures around the handheld cooling devices are also intended to cover the use of this device (i.e. turning on the device, and 5 providing a cryo-anesthetic effect to the skin of the patient by bringing the device into contact with the skin). Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The term “coupled” is defined as “connected” and / or 10 “in communication with,” although not necessarily directly, and not necessarily mechanically. The terms “a” and “an” are defined as one or more unless stated otherwise. The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. 15 As a result, a system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more elements possesses those one or more elements but is not limited to possessing only those one or more elements. Similarly, a method or process that “comprises,” “has,” “includes” or “contains” one or more operations possesses those one or more operations but is not limited to possessing only those one or more operations.

Claims

1. A device comprising:a heat sink., comprising:a heat transfer component comprising a metal and having a first thermal conductivity, wherein the heat transfer component comprises at least one cavity; andat least one thermal insert, each thermal insert configured to be inserted into a corresponding cavity of the at least one cavity, the at least one thermal insert comprising diamond and having a second thermal conductivity which is different from the first thermal conductivity; anda cooling device thermally coupled to a base of the heat sink.

2. The device of claim 1, wherein the heat transfer component comprises a base and a plurality of extrusions extending from the base.

3. The device of claim 2, wherein the plurality of extrusions comprises a plurality of pins having a prismatic or cylindrical structure, preferably wherein the prismatic structure comprises a rectangularshaped base.

4. The device of claim 3, wherein each of the plurality of pins has a cross-sectional area of between 0.03 and 20 mm2, optionally within 1 to 15 mm2.

5. The device of claim 2 or 3, wherein each of the plurality of pins has a length of 0.5 mm to 50mm, and optionally a length of 5mm to 30mm.

6. The device of any one of claims 3 to 5, wherein the density of the plurality of pins along a length of the heat sink is between 0.02 and 10 pins / mm, and / or wherein the density or the plurality of pins along a width of the heat sink is between 0.2 and 10 pins / mm, and / or wherein the density of the plurality of pins across the area of the heat sink is 0.1 pins / cm2 to 50 pins / cm2.

7. The device of any of claims 2 to 6, wherein the at least one cavity extends into the base.

8. The device of any preceding claim, wherein the at least one thermal insert comprises a metaldiamond composite.

9. The device of any preceding claim, wherein the second thermal conductivity is higher than first thermal conductivity.

10. The device of claim 9, wherein the first thermal conductivity is in the range of 150 to 500 —and the second thermal conductivity is in the range of 1000 to 3500 —.

11. The device of any preceding claim, wherein the base and / or the plurality of extrusions are formed from aluminium, copper, or brass.

12. The device of any preceding claim, wherein the at least one thermal insert is formed from an aluminium diamond composite, a copper diamond composite, or a brass diamond composite.

13. The device of any preceding claim, wherein a volume fraction of diamond in the heat sink is between 10% and 90%, optionally between 20% and 80%, and further optionally between 30 and 70%.10 02 2514. The device of any preceding claim, wherein the at least one thermal insert comprises aplurality of layers, wherein the plurality of layers comprises a top layer, a middle layer, and a bottom layer.

15. The device of claim 14, wherein the top layer and the bottom layer are formed fromaluminium, copper, or brass, and wherein the middle layer is formed from an aluminium diamond composite, a copper diamond composite, or a brass diamond composite, optionally wherein the aluminium diamond composite, copper diamond composite, or brass diamond composite comprises carbide coated diamonds.

16. The device of any preceding claim, wherein the at least one thermal insert occupies 5% to90% of the total volume of the heat sink.

17. The device of any preceding claim, wherein the at least one thermal insert has a total volume between 0.5 x 105 m3 and 20 x 105 m3, optionally between 1 x 105 m3 and 11 x 105 m3, and further optionally between 5.5 x 105 m3 and 7 x 10 5 m3.

18. The device of any preceding claim, wherein a total surface area of the at least one thermal insert is between 0.01 and 0.1 m2, optionally between 0.02 and 0.09 m2, and further optionally between 0.045 and 0.065 m2.

19. The device of any preceding claim, wherein the heat transfer component has a mass between0.1 kg and 2 kg.

20. The device of any preceding claim, wherein the heat sink has a bounding box volume within arange of 4,000 mm3 to 600,000 mm3, optionally within a range of 12,500 mm3 to 450,000 mm3, or further optionally within a range of 100,000 mm3 to 350,000 mm3.

21. The device of any preceding claim, wherein the heat sink has an actual volume within a rangefrom 4,000mm3 to 122,000mm3, optionally within a range of 10,000 mm3 to 75,000 mm3, or further optionally within a range of 30,000 mm3 to 60,000 mm3.

22. The device of any preceding claim, wherein the cooling device comprises a thermo-electricdevice.

23. The device of claim 22, wherein the heat transfer component is coupled to the thermo-electricdevice at a plurality of connection points, optionally wherein the connection points are arranged around the periphery of the at least one cavity.

24. The device of any of claims 22 to 23, wherein the thermo-electric device comprises a Peltier-effect device having a hot plate thermally coupled to the base of the heat transfer component, a cold plate, and an interconnect region between the hot plate and the cold plate.

25. A handheld cooling device comprising a housing, a handle attached to the housing, a cooling component for applying a cooling effect to tissue and / or fluid, and the device according to any preceding claim, wherein the cold plate of the thermo-electric device is thermally coupled to the cooling component.

26. The handheld cooling device of claim 25, further comprising one or more fans for dissipating heat from the heat transfer component.

27. The handheld cooling device of any one of claims 25 to 26, further comprising a power source electrically connected to the thermo-electric device, preferably wherein the power source comprises a battery.

28. The handheld cooling device of any one of claims 25 to 27, wherein the cooling component is configured to be cooled by the thermo-electric device to temperatures below 10 degrees, and optionally below 0 degrees Celsius.10 02 25

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