UNIVERSAL FLUID DROPLET EJECTOR

Abstract: A droplet generator (22) comprises a fluid reservoir (58) having a side wall (60) made of glass or quartz, and an end cap (96) made from a silicon plate. The end cap (96) contains a micromachined aperture (24) through which the fluid is ejected. The side wall (60) is thermally fused to the end cap, and no adhesive is necessary. This means that the fluid only comes into contact with the side wall (60) and the end cap (96), both of which are chemically inert. Amplitudes of drive pulses received by the fluid reservoir (58) determine the horizontal displacements of droplets relative to the ejection aperture (24). The drive pulses are varied such that the dropper (22) generates a two-dimentional array (50) of vertically-falling droplets. Vertical and horizontal inter-droplet spacings may be varied in real time. Applications include droplet analysis experiments such as Millikan fractional charge searches and aerosol characterization, as well as material deposition applications.

Description: Universal Fluid Droplet Ejector FIELD OF THE INVENTION invention relates to droplet generation and analysis devices, and in particular to a droplet generator that is chemically and biologically inert. BACKGROUND OF THE INVENTION Droplet generation devices are used in a variety of analysis and characterization applications such as fractional charge searches in particle physics, aerosol characterization in chemistry, and cell-sorting techniques in biology. Such devices are also used in material deposition applications such as inkjet printing and microfabrication. Droplet generators used in conventional analysis applications typically consist of a vertical dropper situated above an analysis chamber. The dropper generates a vertical stream of droplets which is optically analyzed as it falls through the analysis chamber. Depending on the application, the droplets may be subjected to electric fields, air currents, or other perturbations . For examples of droplet generators used for fractional charge searches see the article by M.L. Savage et al . , A Search for Fractional Charges in Native Mercury, Phys . Lett . 167 (B4): 481 (1986), as well as the M.S. thesis of D.C. Joyce, San Francisco State University (San Francisco, CA, 1985) . Desirable properties for droppers used in analysis applications include: the ability to adjust droplet sizes either electronically or by replacing a minimal amount of hardware, ease of replacement for droplet nozzles, ability to generate a large number of analyzable droplets, and chemical inertness of all tubing (including nozzle) . It is important to have a chemically non-reactive dropper. Typical droplet generators contain metal or plastic parts, and may therefore chemically react with or biologically contaminate the fluid under study. Zoltan, in U.S. Pat. No. 3,683,212, shows how to make a dropper that is chemically inert, using glass or other tubing that is necked down to form a nozzle through which droplets are ejected. However, manufacturing such a nozzle requires a highly skilled artisan, and no two nozzles will be identical. Furthermore, the tapering in such a nozzle is generally so gradual that the nozzle tends to clog easily. Using a single nozzle for drop generation is desirable since it allows a significant reduction in total system costs, and in particular in nozzle replacement costs. Typical prior art single-nozzle systems are limited to generating a single stream of droplets, however, and therefore can only provide a limited amount of data within a given field of view of a camera . Droplet generators used in conventional material deposition applications, such as inkjet printing, typically consist of a linear array of vertical nozzles situated closely above the deposition target (e.g. a sheet of paper). Each nozzle ejects droplets at a fixed location as the target moves relative to the array. The dropper array may be used to generate two- dimensional droplet arrays. The requirement for placing the nozzles in close proximity to the target makes imaging the impact points of the droplets relatively difficult. For information on droplet generators used for inkjet printing see for example U.S. Patent Nos . 5,124,716 to Roy, et al . , 3,683,212, and 5,619,234 to Nagato, et al . OBJECTS AND ADVANTAGES OF THE INVENTION In light of the above, it is a primary object of the present invention to provide an easily manufactured and easily reproduced droplet generator that is chemically inert and biologically sterile. It is also an object of the invention to provide a droplet analysis apparatus capable of using a single nozzle to generate a large amount of analyzable data within the field of view of an analysis camera. It is another object of the invention to provide an apparatus capable of modulating in real time the vertical and horizontal inter- droplet spacings of a two-dimensional droplet array. It is another object of the invention to provide a deposition system allowing for easy visualization of droplet impact points on deposition targets. SUMMARY OF THE INVENTION The present invention provides an improved apparatus for generating droplets . The apparatus comprises a liquid reservoir, an ejection means coupled to the reservoir, and a control means in electrical communication with the ejection means, for controlling the ejection means. The liquid reservoir has a side wall made of a silicon- containing compound, such as quartz or glass, and an end cap comprising a silicon plate. This end cap has a micromachined aperture through which liquid droplets are ejected. The end cap is bonded to the reservoir body by a thermal weld. The ejection means generates pressure pulses within the reservoir such that the reservoir ejects droplets through the ejection aperture. The droplets are ejected in a direction having a horizontal component. The pressure pulses, and in particular their amplitudes, determine horizontal displacements of the droplets relative to the ejection aperture. The pressure pulses are controlled by drive pulses generated by the control means and received by the ejection means . The control means generates drive pulses of various amplitudes, such that the reservoir ejects droplets at various horizontal displacements. The ejection means does not physically touch the fluid, and the bond between the side wall and the end cap of the reservoir requires no adhesive; therefore the fluid contacts only the side wall and end cap materials. These materials will not contaminate biological samples, nor will they react chemically with most substances. Furthermore, because the ejection aperture is micromachined, the dropper is easily manufactured and reproduced. The present invention therefore provides an economical and reproducible fluid droplet ejector that is universal in the sense that it can employ a wide variety of fluids . DESCRIPTION OF THE FIGURES Fig. 1-A shows a side view of a preferred apparatus including a dropper of the present invention. Fig. 1-B shows the dropper of Fig. 1-A and a two-dimensional droplet array generated by the dropper, in a side view orthogonal to the view of Fig. 1-A. Fig. 1-C shows a driving pulse sequence used to generate part of the droplet array of Fig. 1-B. Fig. 2-A shows a longitudinal sectional view of the dropper of Fig. 1-B. Fig. 2-B shows a longitudinal sectional view of the end cap of the dropper of Fig. 2-A. Fig. 3 shows a series of side views of the end cap of Fig. 2- B as a droplet is ejected through the dropper aperture. Fig. 4 shows an alternative embodiment of the dropper including a mechanical stirring means. Fig. 5 shows an alternative embodiment of the dropper including a magnetic stirring means . DETAILED DESCRIPTION Fig. 1-A shows a side schematic view (not to scale) of a preferred apparatus 20 of the present invention, suitable for droplet analysis applications and in particular for charge measurement (e.g., Millikan oil drop) experiments. Apparatus 20 comprises a dropper 22 having an ejection aperture 24 for ejecting liquid droplets 32. Ejection aperture 24 is situated above aligned slits in an upper plate 36 and lower plate 38. Upper plate 36 and lower plate 38 are parallel and horizontal, and are connected to a voltage source (not shown) for generating a potential difference between upper plate 36 and lower plate 38. The space between upper plate 36 and lower plate 38 comprises an analysis area 34. A housing 46 defines a convection-free enclosure comprising analysis area 34, such that the trajectories of droplets 32 are not affected by air currents. A light source 40, preferably a strobe, is positioned laterally with respect to analysis area 34, and is capable of illuminating analysis area 34. A CCD camera 44 and imaging optics (including a lens 42) are situated opposite light source 40 relative to analysis area 34, such that droplets 32 within analysis area 34 are imaged onto camera 44. Light source 40, dropper 22, and camera 44 are in electrical communication with control electronics (not shown) situated outside housing 46. A potential difference between upper plate 36 and lower plate 38 generates a uniform vertical electric field 48 within analysis area 34. Electric field 48 oscillates in time as a square wave. Droplets 32 enter and exit analysis area 34 through slits in upper plate 36 and lower plate 38. Droplets 32 within analysis area 34 are illuminated by light source 40 and are imaged through lens 42 onto CCD camera 44. The vertical velocities of droplets 32 are indicative of the electric charge on droplets 32. Fig. 1-B shows dropper 22 and a two-dimensional droplet array 50 generated by dropper 22 , from a side view orthogonal to the view of Fig 1-A. Dropper 22 comprises a fluid reservoir 58 having a side wall 60. The reservoir holds dropper fluid 61. An ejection means 62 is coupled to side wall 60 and laterally encloses side wall 60. Ejection means 62 comprises a piezoelectric disk for constricting side wall 60. Ejection means 62 is in electrical communication with control electronics 64. Ejection means 62 constricts fluid reservoir 58 in response to drive pulses, generating pressure pulses within fluid reservoir 58. The pressure pulses cause the ejection of droplets 32 forming array 50. A first end of a manometer tube 66 is connected to fluid reservoir 58 at its proximal portion opposite aperture 24, for controlling the global pressure within fluid reservoir 58. Tube 66 encloses an inert gas volume 72 adjacent to fluid reservoir 58, and a U-shaped liquid column 76 adjacent to the inert gas 72. In the preferred embodiment, a second end of manometer tube 66 is open to the air. In an alternative embodiment, the second end of tube 66 is connected to a regulator (not shown) that maintains a constant pressure above liquid column 76. Inert gas 72 may be any gas which does not react with dropper fluid 61. Depending on the application, inert gas 72 may be air or a noble gas . The lowest point of manometer tube 66 can be adjusted to cause a level difference Δh between the two surfaces of column 76, which in turn causes a slightly negative pressure to be applied to fluid reservoir 58. The negative pressure prevents the escape of dropper fluid 61 through aperture 24 in the absence of a drive pulse. Meniscus buildup and subsequent liquid escape is also impeded by a horizontal orientation of dropper 22. Liquid escape can cause wetting of the surface surrounding aperture 24. Droplets 32 are ejected through aperture 24 along an ejection direction 80 having a horizontal component 82. The ejection direction is preferably at approximately 45° from the horizontal; alternatively, the ejection direction may be horizontal. Shortly after ejection, the horizontal velocities of droplets 32 are dampened by air friction, and droplets 32 fall vertically downward with a constant velocity determined by Stokes' Law. For droplets having non-zero charge, the terminal velocity depends on whether electric field 48 opposes or reinforces the gravitational force on the droplets . The two-dimensional droplet array 50 generated by dropper 22 comprises a rectangular array portion consisting of parallel falling droplet streams 54a-d. Streams 54a-d are separated by horizontal inter-droplet spacings Δx, while droplets within a single stream are separated by vertical inter-droplet spacings Δy. The horizontal and vertical inter-droplet spacings are controlled by the drive pulses received by ejection means 62. Fig. 1-C illustrates three consecutive sequences of drive pulses generated by control means 64 and received by ejection means 62. The vertical inter-droplet spacing Δy between two consecutive droplets in a vertical stream is determined by the time difference Δt between the drive pulses corresponding to the two droplets. The horizontal spacing Δx between droplets in adjacent streams is determined by the difference in amplitude ΔA between the drive pulses corresponding to the two streams. The pulse width of the pulses is marked w. The drive pulse amplitudes determine the initial horizontal droplet velocities and the location of the droplet break-off points (see below) , thus determining the horizontal droplet displacements at any given time point. Fig. 2-A is a longitudinal sectional view of dropper 22, showing ejection means 62 and side wall 60. Side wall 60 is preferably a glass tube; side wall 60 may also be made of quartz. Quartz is chemically inert to most substances including strong acids and bases; glass is slightly more reactive but is easier to use. Ejection means 62 preferably comprises an annular piezoelectric transducer disk made from lead zirconate titanate, and attached to side wall 60 with epoxy or another high-strength adhesive. An end cap 96 comprising aperture 24 is made of silicon, and is attached to the bottom of side wall 60 by thermal welding. This weld is achieved by heating up the side wall 60 and the end cap 96, while they are in contact with each other, to approximately 600 a C. We have found an ordinary propane torch to be sufficient for this purpose. The weld will form because silicon end cap 96, when exposed to air, develops a thin layer of silicon dioxide on its surface. It is this layer that fuses with the glass (or quartz) side wall. If desired, a layer of silicon dioxide could be applied to end cap 96 using thin film deposition techniques; however, we have not found this step to be necessary. Fig. 2-B shows a longitudinal cross section of end cap 96. Aperture 24 has an inverted frusto-pyramidal or frusto-conical shape, and is made by micromachining silicon end cap 96. The use of micromachined silicon allows dropper 22 to be easily manufactured and easily duplicated. Moreover, the angle of tapering of aperture 24 can be made shallow enough that aperture 24 is resistant to jamming by, for example, stray particles suspended in fluid 61. The combined use of silicon and glass (both chemically inert) in the absence of metal, plastics, or adhesives in contact with the fluid allows the ejection of high-temperature fluids, corrosives, and biological samples requiring sterility. Fig. 3 illustrates end cap 96 as a droplet is generated by dropper 22. A liquid volume 102 is initially in a resting state within aperture 24. Slightly negative pressure acting on liquid volume 102 maintains liquid volume 102 within aperture 24, and prevents the wetting of a bottom surface 100 of end cap 96. As a pressure pulse is applied by ejection means 62, a liquid extension stretches outward from aperture 24. A droplet precursor 106 forms as liquid starts retracting toward aperture 24. Droplet precursor 106 becomes a drop 32 as liquid 108 becomes fully retracted in aperture 24, as a result of the negative pressure wave caused by the relaxation of ejection means 62. The breaking point of droplet 32 is determined by the amplitude of the drive pulse received by ejection means 62. During the retraction of the fluid, air does not become trapped within aperture 24. Liquid from fluid reservoir 58 of dropper 22 then enters aperture 24 from above, restoring the resting state liquid volume 102. Fig. 4 shows another embodiment including means for stirring the dropper fluid 61. The stirring means comprises a filament 73, which can be a thin teflon tube, a wire, or any object that is both longer and thinner than manometer tube 66 and that can transfer mechanical force. Preferably, filament 73 is made of a chemically non-reactive material. Filament 73 is threaded through manometer tube 66. A first end of filament 73 is connected to motor 75; a second end dips into dropper fluid 61 and is tied into a loop 77. Alternatively, loop 77 may be replaced by a knot or a small piece of chemically inert material tied to the second end of filament 73. In yet another embodiment, the second end of filament 73 is flattened into a paddle shape. Motor 75 rotates filament 73, thereby stirring dropper fluid 61. Alternatively, motor 75 could provide a back-and-forth motion to the filament; this motion also causes the dropper fluid to be stirred. In another embodiment of this stirring means, filament 73 is fitted into a sleeve of teflon or other low friction material, so that the filament may move smoothly without hitting the side walls of manometer tube 66. In this embodiment, the second end of filament 73 protrudes out from the sleeve and into dropper fluid 61; the sleeve and filament combination catheterizes manometer tube 66. Another stirring means is shown in Fig. 5. A magnet 81 is placed in dropper fluid 61 within fluid reservoir 58. Preferably magnet 81 is coated with teflon or other unreactive material . A varying magnetic field is then applied to fluid reservoir 58, causing magnet 81 to rotate, nutate, or otherwise move so that it stirs dropper fluid 61. An advantage of including a stirring means (e.g., magnet 81, filament 73) is that apparatus 20 and dropper 22 may be used with a dropper fluid that comprises a carrier fluid and a test material suspended, but not dissolved, in carrier fluid 61. Generating "clean" droplets (without spray) of uniform and small size (-10 μ ) typically requires optimizing regime parameters for dropper 22. To optimize system settings, a drive pulse amplitude corresponding generally to desired horizontal displacements is selected. The drive pulse width is varied until dropper 22 produces clean drops of uniform size. The drive pulse amplitude is then varied for a fixed pulse width setting to find the operating amplitude range in which dropper 22 does not produce spray. If the operating amplitude range is not satisfactory for attaining desired horizontal inter-droplet spacings, the drive pulse width is again varied to a point corresponding to clean droplets. The pulse rise- and fall-times, and the instantaneous pressure applied by manometer 68 also affect droplet stability, and may all be varied during the optimization procedure. For a double pulse technique, in which each drive pulse consists of two closely separated (tens of microseconds) spikes, the interspike separation may also be varied in the initial optimization step, until clean droplets are generated. The present invention does not require that the force field acting on droplets 32 be vertical. More generally, a field (e.g. a combined electric and gravitational field) of arbitrary direction may be used to apply a force on droplets 32. The ejection direction then has a component along an orthogonal direction orthogonal to the applied field. Pressure pulses then determine droplet displacements along the orthogonal direction, relative to ejection aperture 24. Dropper 22 of the present invention is not limited to droplet analysis applications, and may be used for material deposition applications. In such applications, a position adjustment means may be used to adjust the dropper position relative to a target deposition area. The position adjustment means may include a x-y or linear stage on which dropper 22 is mounted, and/or a rotational means allowing rotation of dropper 22 about vertical and/or horizontal axes. Industrial applications of the present invention include the generation of aerosols, e.g., for studies thereon; weighing macromolecules incorporated in droplets 32; microfabrication by accretion of material contained within droplets 32; optical analysis of materials; and analysis of convection patterns. It will be clear to one skilled in the art that the above embodiments may be altered in many ways without departing from the scope of the invention. For example, droplet horizontal displacements need not be controlled by varying drive pulse amplitudes, but may generally be controlled by varying pulse widths or other parameters. Suitable droplet sizes range from about 5 μ to about 100 μm. While droplet sizes are defined to some extent by ejection aperture diameters, pulse widths and amplitudes may also be used to vary droplet sizes within a factor of two of aperture diameter. Ejection means 62 may also be provided in different embodiments. While a piezoelectric ejection means is desirable because of its low cost, low heat generation, low power requirements, and ease of integration with fluid reservoir 58, other ejection means may generally be used in the present invention. Suitable ejection means may include devices using acoustic excitation from focused ultrasound, a focused optical beam that can create a bubble in dropper fluid 61, electrostatic constriction or repulsion, electromagnetic actuation, electrothermal pulse generation, or purely mechanical or pneumatic methods of generating pressure pulses. In yet another embodiment of ejection means 62, manometer tube 66 is configured to give a positive, rather than negative, pressure to fluid reservoir 58, thereby potentially creating a steady stream of ejected fluid. The (potential) steady stream is, however, modified by applying an oscillating force to the exterior of fluid reservoir 58; using, for example, a piezoelectric device. The oscillations set up a wave in the "stream" of ejected fluid; the nodes of this wave correspond to separation between droplets 32. In view of these possible variations, the scope of the invention should be determined by the following claims and their legal equivalents.

Claims: CLAIMS We claim: 1. A chemically unreactive fluid dropper, comprising: a) a fluid; b) a fluid reservoir for holding said fluid, said reservoir comprising: (i) a side wall, said side wall comprising a compound comprising silicon, and (ii) an end cap comprising a silicon plate having an ejection aperture therein, said end cap being thermally welded to said side wall; c) an ejection means for producing pressure pulses in said fluid; and d) a control means in electrical communication with said ejection means, said control means for sending drive pulses to said ejection means; wherein the pressure pulses produced by said ejection means eject said fluid from said fluid reservoir through said ejection aperture. 2. The apparatus of claim 1, wherein said silicon-comprising compound is glass or quartz . 3. The apparatus of claim 1, wherein said ejection aperture is frusto-conical in shape. 4. The apparatus of claim 1, wherein said ejection means ejects a stream of droplets of said fluid from said ejection aperture. 5. The apparatus of claim 4, wherein each of said droplets has a diameter in the range of from about 5 micrometers to about 100 micrometers. 6. The apparatus of claim 1, wherein said ejection means comprises a piezoelectric device mounted on the exterior of said side wall. 7. The apparatus of claim 1, wherein said ejection means comprises an annular piezoelectric transducer disc mounted externally on said side wall, and said annular piezoelectric transducer disc comprises lead zirconate titanate. 8. The apparatus of claim 1, further comprising a stirring means for stirring said fluid. 9. The apparatus of claim 1, further comprising a means for controlling a global pressure in said reservoir. 10. The apparatus of claim 1, further comprising: an upper plate and a lower plate, both said upper plate and said lower plate arranged horizontally and parallel to each other and connected to a voltage source, wherein a space located between said upper plate and said lower plate defines an analysis area, each of said upper plate and said lower plate having an aligned slit therein; a housing defining a convection-free enclosure, said convection-free enclosure comprising said analysis area; a light source positioned laterally with respect to said analysis area and adapted to illuminate said analysis area; a CCD camera in combination with imaging optics, said CCD camera located opposite said light source relative to said analysis area, such that droplets within said analysis area may be imaged onto said CCD camera; and electronic control means, located external to said housing, wherein said light source, said dropper, and said CCD camera are in electrical communication with said control means. 11. A method for producing fluid droplets, comprising the steps of : a) providing a fluid dropper, wherein the fluid dropper comprises an ejection means, a control means in communication with the ejection means, and a chemically inert fluid reservoir; the fluid reservoir including a side wall, and an end cap having an ejection aperture therein, wherein the ejection means is in communication with the fluid reservoir; b) providing a fluid in the fluid reservoir; and c) applying, via the ejection means, a plurality of pressure pulses to the fluid. 12. The method of claim 11, further comprising the step of: d) prior to said step c) , applying a slightly negative pressure to the fluid in the fluid reservoir; 13. The method of claim 11, further comprising the step of: e) prior to said step c) , sending, via the control means, a plurality of drive pulses to the ejection means thereby enacting said step c) . 14. The method of claim 13, wherein the ejection means comprises a piezoelectric device, and said step e) comprises supplying a varying electric current to the piezoelectric device. 15. The method of claim 11, further comprising the step of stirring the fluid in the fluid reservoir. 16. The method of claim 11, wherein said step c) causes at least one droplet of the fluid to be ejected from the ejection aperture. 17. The method of claim 16, wherein the at least one droplet ejected from the ejection aperture has a diameter in the range of from about 5 micrometers to about 100 micrometers . 18. The method of claim 11, wherein the ejection means comprises an annular piezoelectric transducer disc . 19. The method of claim 11, wherein the side wall comprises a compound comprising silicon, and the end cap comprises a silicon plate. 20. A method of making a fluid dropper, comprising the steps of: a) providing an end cap having an ejection aperture therein; b) providing a side wall of a fluid reservoir; c) thermally fusing the end cap to the side wall; d) providing an ejection means and a control means; e) securing the ejection means externally to the side wall; and f) coupling the ejection means to the control means . 21. The method of claim 20, wherein said step a) comprises micromachining the ejection aperture in the end cap. 22. The method of claim 20, wherein the end cap comprises a silicon plate having a non-reactive layer, the non- reactive layer being weldable to glass . 23. The method of claim 22, wherein the non-reactive layer is formed by a thin film deposition technique. 24. The method of claim 22, wherein the non-reactive layer comprises silicon dioxide. 25. The method of claim 20, wherein the side wall provided in said step b) comprises quartz or glass. 26. The method of claim 20, wherein said step f) comprises coupling a piezoelectric device externally to the side wall . 27. A method for forming a plurality of droplets, comprising the steps of: a) providing a fluid dropper, wherein the fluid dropper comprises an oscillating force means, a control means in communication with the oscillating force means, a fluid reservoir, and a manometer tube coupled to the fluid reservoir; the fluid reservoir including a side wall, and an end plate having an ejection aperture therein, wherein the oscillating force means is in communication with the fluid reservoir and is adapted for applying an oscillating force to the fluid reservoir; b) providing a fluid in the fluid reservoir; c) applying a positive pressure to the fluid in the fluid reservoir via the manometer tube, wherein the positive pressure has the potential to provide a steady stream of fluid from the ejection aperture; and a) applying an oscillating force to the fluid reservoir, wherein oscillations in the oscillating force induce a wave in the steady stream of fluid, the wave having nodes, and the nodes corresponding to a separation of the steady stream of fluid into a plurality of droplets. 28. The method of claim 27, wherein the oscillating force is applied to the exterior of the fluid reservoir via a piezoelectric device in communication with the fluid reservoir . 9. An apparatus for providing droplets of a fluid, comprising: a) a chemically inert fluid reservoir for containing the fluid, said fluid reservoir comprising an end cap and a side wall, said end cap having an ejection aperture therein; b) positive pressure means in communication with said fluid reservoir for applying a positive pressure to the fluid, wherein said positive pressure means has the potential for providing a steady stream of the fluid from said ejection aperture; and c) oscillating force means, in communication with said fluid reservoir, for applying an oscillating force to said side wall of said fluid reservoir. 30. The apparatus of claim 29, further comprising electronic control means, in communication with said oscillating force means, for controlling said oscillating force means. 31. The apparatus of claim 29, wherein said oscillating force means comprises a piezoelectric device . 32. The apparatus of claim 29, wherein said positive pressure means comprises a regulator. 33. The apparatus of claim 29, wherein said side wall comprises a compound comprising silicon, said end cap comprises a silicon plate, and said ejection aperture is frusto-conical .

Inventors: LEE ERIC R, PERL MARTIN L, LEE, ERIC, R., PERL, MARTIN, L.
Applicants: UNIV LELAND STANFORD JUNIOR, THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNI
Application year: 1998
Main classification: B41J2
IPC codes: B01L3, B41J2, B41J29