WO2014016563A1

WO2014016563A1 - Powder discharge gun

Info

Publication number: WO2014016563A1
Application number: PCT/GB2013/051838
Authority: WO
Inventors: Simona FRANCESE; Heath Reed; Jonathan Wheat; Rosalind WOLSTENHOLME
Original assignee: Sheffield Hallam University
Priority date: 2012-07-23
Filing date: 2013-07-11
Publication date: 2014-01-30
Also published as: GB2504276A; GB201213065D0

Abstract

A powder discharge gun (100) having a housing (101) defining a main body and a supply barrel (200) having an inlet and an outlet (104). A powder supply mechanism (108) supplies and temporarily retains powder at the barrel to allow pressurised gas to force the powder out through the outlet. The powder is dispensed through a nozzle (103) that has a length aligned substantially with the longitudinal axis of the barrel (200) with the conduit having one or more turns spaced longitudinally relative to the longitudinal axis.

Description

Powder Discharge Gun

The present invention relates to a powder discharge gun configured to discharge powder from a nozzle region of the gun.

Fingermarks results from the transfer of substances present at the surface of the fingertips onto a contact surface. Accordingly, fingermarks can comprise endogenous species (natural secretions) and exogenous substances, the latter being dependent upon any prior contact of the skin of the fingertips with other chemicals or substances.

The type of endogenous species in any one fingermark may be numerous as the glands at the palm of the hands secrete specific substances and in many cases the fingers regularly contact other areas of the body, such as the face. Fingermarks can also comprise opaque materials such as blood, dirt, oils and paint. These opaque materials, when present to an appreciable level, create marks that are termed patent marks and are readily visible.

However, fingermarks that are created to a large extend by transparent substances or materials such as gland secretions, are termed latent marks and are not readily visible without some form of optical, chemical or physical enhancement. A range of methods have been proposed and developed to aid visualisation of fingermarks. Currently employed enhancement methods can be categorised as optical, physical, physico-chemical or chemical, commonly used examples of each being UV light, black powder, cyanoacrylate fuming and ninhydrin, respectively. The Home Office Scientific Development Branch (HOSDB) publish the Manual of Fingerprint Development

Techniques based on their research and testing. [Bowman, V.; Manual of fingerprint development techniques, 2^nd ed.; Police Scientific Development Branch, Home Office, Sandridge, UK, 2004]. The manual details the techniques that have been approved for operational use and the order in which they should be applied for a specific set of conditions (primarily surface type and contact with water). The processing flow charts are organised at the first level by the type of surface on which the fingermark is deposited: smooth non-porous, rough non-porous, paper and cardboard, plastics, metal, raw wood, adhesive coated surfaces etc. This necessarily means that the choice of enhancement technique depends largely on the type of deposition surface rather than the chemical composition of the fingermark in question.

Currently, the most widely used technique employed by the forensic community for visual fingermark identification involves the brushing of the contact surface with metal oxide powders. The marks may then be extracted by 'lifting' for subsequent analysis. Recently, fingermark analysis has benefited of sophisticated spectroscopic imaging and analysis to obtain chemical information of the constituent species. Example techniques include matrix assisted laser desorption ionisation mass spectrometry imaging (MALDI-MSI)

[Wolstenholme, R.; Bradshaw, R.; Clench, M.R.; Francese, S. Rapid Commun Mass Spectrom, 2009, 23, 3031]. Other spectroscopic techniques are also described in US 4,708,882, WO 2010/007443 and US 5,099,131.

However, conventional apparatus and methods for dispensing enhancing powders make contact with the surface of deposition by means of a brush. This means that these methods are wasteful and, moreover, could lead to crime scene cross contamination (DNA or other substances transfer from one fingermark to another). What is required therefore is a device or apparatus that solves the above problems. Accordingly, it is an objective of the present invention to provide a device configured to firstly dispense a controlled quantity of a powder onto a contact surface in a contactless manner. Additionally, a further objective of the present invention is to distribute uniformly the powder over the contact surface at the region of the fingermark. Such a device is advantageous to reliably and repeatedly apply a predetermined quantity of powder onto the surface without disrupting the fingermark sample.

The objectives are achieved by providing a hand-held powder discharge gun that utilises a pressurised gas to expel a predetermined quantity of an analytical powder onto the contact surface. In one embodiment, controlling the quantity of powder discharged is achieved using cartridges that may be loaded into a propulsion supply barrel with the contents of the cartridge then discharged via a spray nozzle using a pressurised gas source. Additionally, a more uniform distribution of powder at the contact surface is achieved by configuring the nozzle with at least one conduit that comprises a curved path in the longitudinal direction of the barrel that provides riffling of the powder as it is discharged to facilitate airborne phase mixing which has been observed to reduce the tendency for the powder to cake. According to a first aspect of the present invention there is provided a powder discharge gun comprising: a housing defining a main body of the gun; a supply barrel having an inlet and an outlet, the inlet in fluid communication with a source of pressurised gas; a powder supply mechanism to supply and temporarily retain the powder at the barrel to allow the pressurised gas to force the powder out through the outlet; at least one nozzle provided in fluid communication with the outlet, the nozzle having at least one internal conduit to direct the discharge of powder from the gun; a trigger operative on a valve to control the flow of gas through the barrel and the discharge of powder through the nozzle; wherein the at least one nozzle comprises a length aligned substantially with the longitudinal axis of the barrel and the at least one conduit having one or more turns spaced longitudinally relative to the longitudinal axis.

The present powder discharge gun is suitable for use with a variety of different powders including in particular metal oxide powders typically used by the forensic community in addition to powders used within the spectroscopic analysis field including in particular MADI matrix powders. The present invention is particularly well suited for use with MALDI matrixes enabling subsequent MALDI MSI analysis to be conducted. In particular, one of the factors for the success of MALDI MS and MSI is the ratio between the matrix and the analyte. Gross and differential matrix distribution on the fingermark may result in unsuitable matrix/analyte ratios in the interested areas which could lead to absence of ion signal; this in turn may result in a discontinuous visualisation of the ridge pattern as well as possibly preventing the detection of substances forensically relevant (drugs of abuse, medications, explosives etc.). The present apparatus is configured to optimise powder distributions at the analyte. Optionally, the present invention may comprise a tuneable 'secondary' gas flow control to remove excess material.

Preferably, the powder supply mechanism comprises a cartridge mount assembly to mechanically advance a plurality of cartridges to a region of the barrel. Optionally, the powder supply mechanism comprises a supply tube to connect the barrel to a powder supply reservoir.

Preferably, the gun further comprises a pressurised gas canister removably mounted at the gun via a canister mount. As will be appreciated, the canister mount may comprise any form of releasable mounting mechanism such as screw threads, bayonet fixings, lure connections, push-fit or snap-click connections.

Preferably, the discharge gun further comprises at least one laser generator to project a laser beam substantially in the direction of the longitudinal axis of the barrel. Preferably, the gun comprises a plurality of laser generators positioned at the gun to project laser beams in a direction substantially along the longitudinal axis. Preferably, the laser generators are positioned at the barrel outlet or nozzle region of the gun so as to project their respective laser beams from a region surrounding the nozzle. Preferably the laser generators are aligned at a tangential angle relative to the longitudinal axis of the barrel so as to generate respective laser beams that are convergent to a single point spaced from the end of a nozzle by a predetermined distance as a product of the manual (or automatic) adjustment. Preferably, the laser generators are adjustably mounted at the gun such that the respective angles by which the laser beams project relative to the longitudinal axis of the barrel are adjustable to allow alteration of the separation distance of the point of convergence of the laser beams relative to the nozzle. Additionally, using three beams allows the operator to control the angle at which the barrel is orientated relative to the target surface. Preferably, the gun further comprises a laser adjustment mechanism configured to alter an angle of projection of the laser beams relative to the longitudinal axis. Preferably, the adjustment mechanism comprises a dial, switch, button or knob that may be adjusted by the thumb and fingers to adjust the position of the laser generators relative to the gun that change the direction along which the respective laser beams project from the generators relative to the longitudinal axis of the barrel. Preferably, the gun further comprises at least one cartridge comprising the powder, the cartridge releasably mountable at a region of the barrel. Preferably, the cartridge forms part of an array of cartridges mounted at a cartridge magazine. Optionally, individual cartridges may be mounted at the gun and then removed post firing.

Preferably, the gun further comprises at least one sealing gasket mounted at the region of the barrel to close against the cartridge when positioned at the barrel and to form a fluid tight seal at the cartridge to prevent gas escaping from the region of the cartridge when flowing through the barrel. Preferably, the gun comprises a plurality of sealing gaskets that are configured to abut one or more regions of the cartridge at or shortly after the cartridge has been introduced at the region of the barrel. Preferably, the movement of the sealing gaskets into position about the cartridge is controlled by actuation (depression) of the trigger.

Optionally, the nozzle is not detachable from the gun or is integrally formed at an end region of the barrel. Preferably, the nozzle is detachably mounted at the barrel or the outlet region of the barrel.

Preferably, the turns of the at least one conduit extend in a helical manner relative to the longitudinal axis. Preferably, the nozzle comprises a plurality of conduits extending within the nozzle and arranged around one another in a helical manner. Optionally, the nozzle comprises 3, 6, 9 or 12 conduits each extending in a helical manner around the longitudinal axis of the barrel and/or the nozzle. Preferably, a diameter of each helix of each conduit is identical. Optionally, the turns extend through greater than 90° in a circumferential direction relative to the longitudinal axis. Optionally, the turns extend through greater than 180° in a circumferential direction relative to the longitudinal axis. Optionally, the turns extend through between 180° to 720° and preferably between 180° to 360 in a

circumferential direction relative to the longitudinal axis. Preferably, the length of each conduit corresponds to the length of the nozzle such that the conduits follow a helical path extending from one end of the nozzle to the other end along the entire length of the nozzle. Accordingly, the degree of curvature of the conduits is the angle around which the conduit is curved in a circumferential direction around the longitudinal axis of the nozzle and/or barrel from the start (inlet) to the finish (outlet) of each conduit. Preferably, the gun further comprises a battery to provide a power source to working components of the gun.

Optionally, the gun further comprises a control device to set a duration the value is open. Optionally, the control device is capable of controlling the time period to within a 100th of a second.

According to a second aspect of the present invention there is provided a kit of parts for a powder discharge gun, the kit comprising: a housing defining a main body of the gun; a supply barrel having an inlet and an outlet; a pressurised gas canister positionable in fluid communication with the inlet of the supply barrel; a powder supply mechanism to supply and temporarily retain powder at the barrel to allow the pressurised gas to force the powder out through the outlet; at least one nozzle positionable at the outlet of the barrel, the nozzle having at least one internal conduit to direct discharge of the powder from the gun, the at least one nozzle comprising a length aligned with the longitudinal axis of the barrel and the at least one conduit having one or more turns spaced longitudinally relative to the axis; a trigger and a valve to control the flow of gas through the barrel and operative to discharge powder through the nozzle; a plurality of cartridges each containing powder, the cartridges positionable at the barrel.

Preferably, the kit of parts further comprises a cartridge magazine, to mount the cartridges in-series and to retain the cartridges in the in-series arrangement ready for supply to the region of the barrel. A specific implementation of the present invention will now be described by way of example only, and with reference to the accompanying drawings in which:

Figure 1 is a perspective external view of a powder discharge gun according to a specific implementation of the present invention;

Figure 2 is a further perspective view of the discharge gun of figure 1 with various components removed for illustrative purposes; Figure 3 is a perspective view of a laser generator arrangement and a laser alignment adjustment mechanism according to a specific implementation of the present invention; Figure 4 is a perspective external view of a nozzle of the discharge gun of figure 1 according to a specific implementation of the present invention;

Figure 5 is a perspective part cross sectional view of the nozzle of figure 4. Referring to figures 1 and 2, the discharge gun comprises a housing 101 that forms the main body of the gun 100. Housing 101 is shaped to provide a handle region 102 suitable to be grasped such that gun 100 may be held by one hand. Gun 100 further comprises a nozzle 103 having a discharge outlet 104 from which powder is discharged. Three laser generators 105 are mounted externally of housing 101 at a region close to and slightly behind nozzle 103. Each generator 105 is mounted at gun 100 via an adjustable mount 112 to allow adjustment of the position of each generator 105 relative to housing 101 and in particular nozzle 103. Mount 112 is configured to ensure the equal movement of generators 105 relative to housing 101. Each generator 105 further comprises a laser outlet 111 through which respective laser beams are emitted so as to project forwardly of gun 100 in a direction along which powder is fired from nozzle outlet 104. According to the specific implementation, each laser generator 105 is substantially elongate and comprises a longitudinal axis. Referring to figure 2, the gun comprises a barrel 200 through which powder to be discharged from the gun is fired during any one firing operation. Barrel 200 is elongate and projects rearwardly of nozzle 103. Nozzle 103 further comprises a duct section 208 housing a plurality of internal conduits. Duct 208 is also elongate and is aligned coaxially and in fluid communication with barrel 200.

As shown in figures 1 and 2, the longitudinal axis of each laser generator 105 is inclined slightly relative to the longitudinal axis of duct 208 and barrel 200 such that these axes are transverse. Accordingly, laser beams emitted from each outlet 111 converge at a predetermined distance from nozzle 113. Barrel 200 comprises an outlet 201 and an inlet 202 with outlet 201 positioned in fluid communication and direct contact with duct 208.

Gun 100 further comprises a pressurised gas canister 106 the outlet end of which is mounted at a region neighbouring barrel inlet 202 via mount 203. According to the specific implementation, an end of canister 106 comprises screw threads to mate with corresponding threads provided internally at mount 203.

The adjustable mount mechanism 112 for laser generators 105 further comprises a dial 107 rotatably mounted at a rear position of gun 100. Dial 107 is coupled to mount 112 such that rotational adjustment of dial 107 actuates mount 112 to adjust the relative transverse angle between the longitudinal axis of each laser generator 105 and the longitudinal axis of the barrel 200 and duct 208. A trigger 110 is provided at housing 101 towards a region of handle 102 and is capable of being depressed by one or more fingers of the hand. Trigger 110 is mounted at gun 100 via a spring biased mounting 207. Trigger 110 is also coupled to at least one electronic switch 206 that is coupled electronically to other components of the gun 100. In particular, switch 206 acts on a valve 204 located at a region of canister mount 203 and is operative to control the release of gas from canister 106 which then flows into barrel 200. A gap region 209 is provided between mount 203 and barrel inlet 202 and is sized appropriately to accommodate a single cartridge 109 that houses the powder to be discharged from nozzle outlet 104. Sealing gaskets (not shown) are provided at the respective ends of mount 203 and barrel inlet 202 so as to seal automatically against cartridge 109 when inserted at location 209 as trigger 110 is actuated.

According to the specific implementation, a plurality of cartridges 109 are mounted in an in-series arrangement to form a cartridge magazine 108 that may be advanced

automatically through region 209 as trigger 110 is actuated. Accordingly, housing 101 comprises a first magazine aperture 113 and a second aperture (not shown) on an opposite side of housing 101 such that magazine 108 may pass through the gun body, defined by housing 101, via gap region 209. The mechanism for advancing each cartridge 109 towards the firing position 209 coaxially with barrel 200, may comprise any known mechanical arrangement used within the powder discharge gun or fire arms fields. In particular, the mechanism may be actuated

automatically each time trigger 110 is depressed and/or released. Such a mechanism could be controlled electronically with the control electronics coupled to, for example, switch 206. According to the specific implementation, the magazine 108 comprises a

substantially linear magazine arrangement. However, further specific embodiments may comprise cartridges preloaded within a circular magazine such that the advancing mechanism is similar to a revolver type arrangement. Further embodiments may comprise a click-in magazine in which the cartridges are spring biased within the magazine towards the direction of firing position 209. A suitable attachment region and aperture (not shown) would then be located at housing 101 to releasably engage the magazine. Referring to figure 3, the adjustable mount 112 for laser generators 105 comprises an annular disk 301 rotatably mounted within housing 101. Disk 301 comprises a central aperture 303 coaxially mounted to surround barrel 200. Three cam flanges 302 project radially outward from disk 301. Each flange 302 is tapered in a radial direction along its circumferential length such that one end of each flange 302 projects a greater radial distance from disk 301 than a second end.

A stabilising arm 305 also projects radially from disk 301 so as to extend through slot 114 formed in housing 101. A rear portion 304 of each laser generator 305 is positioned in contact with a respective flange 302. Additionally, each laser generator 105 is pivotally mounted at housing 101 via a pivot mounting 300 projecting from a front region 306 of each generator 105.

Accordingly, by rotating disk 301 about the longitudinal axis of barrel 200, each laser generator 105 pivots about pivot mounting 300 as each respective rear portion 304 is pushed radially outward by each flange 302 relative to the longitudinal axis of barrel 200. This operation may be controlled via dial 107 and/or adjustment of arm 305 within slot Referring to figures 4 and 5, nozzle 103 comprises a disk-shaped end region 400. Duct 208 is formed integrally with disk 400 and project rearwardly therefrom. Duct 208 terminates at nozzle outlet 104 projecting from forward face of disk 400. An internal bore 502 extends centrally through duct 208 from a first inlet end 500 to a second outlet end 501. Inlet 500 is provided in fluid communication with outlet 201 of barrel 200. Where duct 208 and barrel 200 are formed non-integrally, a sealing gasket (not shown) may be positioned at this interface to provide a fluid tight seal. Bore 502 is divided into a plurality of conduits 401 by an elongate baffle 402 extending lengthwise through bore 502. Baffle 402 divides bore 502 into six internal conduits and is shaped to comprise conduit walls that each follow a helical path that turn circumferentially around the longitudinal axis of duct 208 and barrel 200. Accordingly, each conduit 401 follows a helical path between ends 500 and 501. According to the specific

implementation, the cross sectional area of each conduit 401 is the same and substantially uniformed along the length of duct 208 between ends 500 and 501.

Claims

1. A powder discharge gun comprising:

a housing defining a main body of the gun;

a supply barrel having an inlet and an outlet, the inlet in fluid communication with a source of pressurised gas;

a powder supply mechanism to supply and temporarily retain the powder at the barrel to allow the pressurised gas to force the powder out through the outlet;

at least one nozzle provided in fluid communication with the outlet, the nozzle having at least one internal conduit to direct the discharge of powder from the gun;

a trigger operative on a valve to control the flow of gas through the barrel and the discharge of powder through the nozzle;

wherein the at least one nozzle comprises a length aligned substantially with the longitudinal axis of the barrel and the at least one conduit having one or more turns spaced longitudinally relative to the longitudinal axis.

2. The discharge gun as claimed in claim 1 wherein the powder supply mechanism comprises a cartridge mount assembly to mechanically advance a plurality of cartridges to a region of the barrel.

3. The discharge gun as claimed in claim 1 wherein the powder supply mechanism comprises a supply tube to connect the barrel to a powder supply reservoir.

4. The discharge gun as claimed in claim 1 further comprising a pressurised gas canister removably mounted at the gun via a canister mount.

5 The discharge gun as claimed in any preceding claim further comprising at least one laser generator to project a laser beam substantially in the direction of the longitudinal axis of the barrel.

6. The discharge gun as claimed in claim 5 comprising a plurality of laser generators positioned at the gun to project laser beams in a direction substantially along the longitudinal axis.

7. The discharge gun as claimed in claim 6 further comprising a laser adjustment mechanism configured to alter an angle of projection of the laser beams relative to the longitudinal axis.

8. The discharge gun as claimed in any preceding claim further comprising at least one cartridge comprising powder, the cartridge releasably mountable at a region of the barrel.

9. The discharge gun as claimed in claim 8 further comprising at least one sealing gasket mounted at the region of the barrel to close against the cartridge when positioned at the barrel and to form a fluid tight seal at the cartridge to prevent gas escaping from the region of the cartridge when flowing through the barrel.

10. The discharge gun as claimed in any preceding claim wherein the nozzle is not detachable from the gun or is integrally formed at an end region of the barrel.

11. The discharge gun as claimed in any one of claims 1 to 9 wherein the nozzle is detachably mounted at the barrel of the outlet region of the barrel.

12. The discharge gun as claimed in any preceding claim wherein the turns of the at least one conduit extend in a helical manner relative to the longitudinal axis.

13. The discharge gun as claimed in any one of claims 1 to 11 comprising a plurality of conduits extending within the nozzle and arranged around one another in a helical manner.

14. The discharge gun as claimed in any preceding claim wherein the turns extend through greater than 90° in a circumferential direction relative to the longitudinal axis.

15. The discharge gun as claimed in any preceding claim wherein the turns extend through greater than 180° in a circumferential direction relative to the longitudinal axis.

16. The discharge gun as claimed in any preceding claim wherein the turns extend through between 180° and 720° in a circumferential direction relative to the longitudinal axis.

17. The discharge gun as claimed in any preceding claim further comprising a battery to provide a power source to working components of the gun.

18. A kit of parts for a powder discharge gun, the kit comprising:

a housing defining a main body of the gun;

a supply barrel having an inlet and an outlet;

a pressurised gas canister positionable in fluid communication with the inlet of the supply barrel;

a powder supply mechanism to supply and temporarily retain powder at the barrel to allow the pressurised gas to force the powder out through the outlet;

at least one nozzle positionable at the outlet of the barrel, the nozzle having at least one internal conduit to direct discharge of the powder from the gun, the at least one nozzle comprising a length aligned with the longitudinal axis of the barrel and the at least one conduit having one or more turns spaced longitudinally relative to the axis;

a trigger and a valve to control the flow of gas through the barrel and operative to discharge powder through the nozzle;

a plurality of cartridges each containing powder, the cartridges positionable at the barrel.

19. The kit of parts as claimed in claim 18 further comprising a cartridge magazine, to mount the cartridges in-series and to retain the cartridges in the in-series arrangement ready for supply to the region of the barrel.