DE102013019441B4 - Atomizer system and its use - Google Patents

Abstract

Atomizer system (100) having a spray chamber (18) and a spray head (1) with a gas supply line (2a) and with a liquid supply line (2b), the spray head (1) having a mixing area in its interior and being gas-tight with the spray chamber (18). is connected via a fastening means, the spray head (1) has a gas mass flow controller (13) and a flow rate controller (14), characterized in that the spray head (1) has a taper in a section facing the spray chamber (18), which has a two-substance nozzle inner mixture (17) and the spray chamber (18) has a tapering section on the section opposite the nozzle (17) with a spray chamber angle β of 30 ° to 60 ° and thus acts as an acoustic resonance body.

Description

The invention relates to an atomizer system for generating aerosol with a small droplet size and its use.

[State of the art]

The atomization of liquids in atomization systems is carried out in order to produce small droplets with a large reactive liquid surface, for example in carburetors and humidifiers. This promotes mass and heat exchange processes, such as those that occur in evaporation and combustion processes.

Atomization systems are also used to ensure uniform surface coatings or to generate sufficient impulse transfer for cleaning tasks.

Atomizers are also used in spectrometry (e.g. in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry) and are used for the chemical analysis of substances by atomizing substances.

In addition to these applications, there are atomizer systems for medical or cosmetic sprays that are used to directly wet the skin with an active ingredient or are inhaled as an aerosol, for which the atomizer systems are available in different designs with a structurally defined amount of aerosol released per stroke. The publications are the state of the art DE 29 821 687 U1 , WO 2008/001 301 A2 , DE 202 11 577 U1 , DE 10 2007 056 273 A1 , DE 201 00 648 U1 , EP 1 491 820 A2 and DE 10 2010 012 554 A1 known.

Depending on the type of energy supply, atomizer nozzles of atomizer systems can be divided into the following classes:

Single-component pressure nozzles

The energy supplier is the liquid to be atomized. This is fed under pressure to the single-substance pressure nozzle. Depending on the nozzle design, a liquid jet or a liquid lamella is generated at the nozzle mouth. Drop formation begins at a certain distance from the nozzle opening. Typical representatives of this type of nozzle are turbulence, flat jet, impact and hollow cone pressure nozzles.

Dual fuel or pneumatic nozzles

These nozzles work on the principle of a jet pump. The energy source is a gas or steam flowing at high speed. The liquid to be atomized can be supplied with almost no pressure. Some of these nozzles work self-priming. Two-fluid nozzles are divided into nozzles with an internal mixture and nozzles with an external mixture. Typical representatives of this type are matrix preparation devices for imaging mass spectrometry of biological tissue.

The nozzles, which are two-substance nozzles, of conventional atomizer systems for matrix preparation work with an open spray device without gas-dynamic control. They only reach a drop size of more than 10 µm, which enables imaging mass spectrometric analysis with a spatial resolution of 20 µm at best.

Because the droplets are too large, the spatial resolution that can be achieved with the state of the art is not sufficient to meaningfully image biological structures at the cellular level.

With dual-fluid or pneumatic nozzles, a gas or vapor mass flow flowing at high speed serves as an energy supplier for the atomization process. This offers the advantage that, in contrast to single-substance pressure nozzles, even smaller volume flows of higher viscosity liquids can be atomized into a fine range of drop sizes. The mass flow ratio µ between the gas and the liquid plays an important role here. $\mu =\frac{{\dot{m}}_G}{\dot{m}}$

This mass flow ratio is also referred to as loading. The drops produced tend to become finer as the load increases. The larger the loading number, the more leeway there is with regard to the mass flows for a constant, characteristic droplet diameter.

Two-fluid external mixture nozzles

The liquid to be atomized and the gas only interact with one another outside the nozzle. The prefilming nozzle is often found here. The liquid emerges from the center of the nozzle with almost no pressure. The gas flows at high speed from a surrounding ring channel. This results in a negative pressure in the vicinity of the nozzle opening, which spreads the liquid as a film on the prefilming surface. This thin film hits the gas flowing at high speed and is broken up into fine droplets. Under Under certain conditions, this type of nozzle works self-priming.

Two-fluid nozzles with internal mixture

With these types of nozzles, a two-phase mixture is created inside the nozzle. This has a low speed of sound. This results in a so-called pressure jump in the nozzle exit plane. Drops with a critical diameter are thereby further broken up and contribute to a high proportion of fine drops in the spray. In contrast to the two-fluid nozzles of external mixture, gas and liquid pressure must be coordinated. In this respect, greater control engineering effort is required.

[Task]

The object of the invention is to provide an atomizer system which ensures an aerosol made up of drops with a diameter of less than 10 μm that are evenly distributed over the surface in the aerosol stream.

[solution to the task]

The solution to this problem results from the features of the main claim, while advantageous refinements and developments of the invention can be found in the subclaims.

The invention consists of an atomizer system 100 comprising a spray head 1 and a spray chamber 18 which can be connected to this spray head in a gas-tight manner. These are made, for example, of plastic, glass or ceramic.

The spray head 1 has a taper in a section facing the spray chamber 18, which is designed as a nozzle 17 for atomizing liquid with gas. The spray head 1 thus has a two-phase nozzle with an internal mixture.

Furthermore, the spray head 1 comprises at least one gas supply line 2a and at least one liquid supply line 2b. The gas and the liquid reach the interior of the spray head 1 through these supply lines. The area in which the gas and liquid meet and form an aerosol is the mixing area 10.

Gas is any substance or mixture of substances that is gaseous under the operating conditions prevailing in the atomizer system. For example, this is a chemically inert gas such as nitrogen, helium or CO ₂ .

The geometry of the nozzle 17 of the atomizer system is described by the nozzle angle alpha. This describes the angle between the outlet surface of the spray head 1 and the wall of the spray head at its outlet opening. This angle determines how much the cross-sectional area of the mixing area narrows towards the outlet opening.

At a nozzle angle alpha of 90°, the outlet opening is at its maximum and no nozzle effect is achieved. At a nozzle angle alpha of 0°, the opening is closed.

In order to generate a uniformly flat aerosol stream, the spray head 1 in the atomizer system according to the invention has a nozzle angle alpha of 40° to 80°, preferably 55° to 65°, on the nozzle 17.

Spray head 1 and spray chamber 18 are connected to one another in a gas-tight manner. The connection is made, for example, via thread, adhesive, press fit or another suitable fastener that ensures a gas-tight connection. Alternatively, an additional seal is used.

This ensures that no material is transported except through the nozzle 17. In particular, no gas from outside can penetrate into the atomizer system.

In one embodiment, the connection between spray head 1 and spray chamber 18 is designed to be reversibly closable. The closure takes place, for example, via a thread using screws. This allows a sample to be introduced into the spray chamber 18 without further opening in the spray chamber 18.

The gas supply to the spray head 1 is regulated. For this purpose, the spray head 1 has a gas mass flow controller 13. This is, for example, a manually or electrically controllable movable valve or via a throttle valve (needle valve), for example with a motor.

Preferably, the gas supply line 2a also has a gas mass flow sensor in order to either directly control the gas flow regulator and/or display a pressure gradation value to the user, for example through a display element. In order to generate a flat, uniform aerosol flow with particles smaller than 10 µm, pressure gradations in the range from 0.1 bar to 2 bar are preferred, particularly preferably around 1 bar. The gas source is a gas reservoir, e.g. a syringe or gas bottle.

The liquid supply into the mixing area 10 of the spray head 1 is also regulated. For this purpose, the spray head 1 includes a flow rate controller 14 for liquid. This is, for example, a manually or electrically controllable movable valve, for example with a motor.

Preferably, the liquid supply line 2b additionally has a flow rate sensor in order to either directly control the flow rate controller 14 for liquid and/or to display a value to the user, for example through a display element. This flow rate sensor measures the flow rate and is designed, for example, as a thermal flow rate sensor.

The fluid source is a fluid reservoir, such as a syringe or tank. In order to generate a flat, uniform aerosol flow with particles smaller than 10 µm, the flow rate is in a range from 0.1 µl/min to 100 µl/min, preferably 1 µl/min to 50 µl/min.

The gas mass flow controller 13 and the flow rate controller for liquid 14 are independent of one another in their function.

In one embodiment, the nozzle 17 is designed to be closable. This enables rapid regulation of the aerosol flow.

In a further embodiment, the atomizer system according to the invention comprises at least one sensor on the nozzle 17 for monitoring a flow of the aerosol through the nozzle 17. This sensor ensures a uniform aerosol flow over the area with particles smaller than 10 μm. Its function is independent of other sensors (e.g. gas mass flow sensor and/or flow rate sensor).

In a further embodiment, the atomizer system according to the invention comprises a spray chamber 18 with a special geometry. It has a tapering section opposite the nozzle 17 with a spray chamber angle beta of 30° to 60°, preferably 40° to 50°. This ensures a uniform aerosol flow with particles smaller than 10 µm. In one application, the spray chamber is flooded with gas, for example nitrogen, before the actual spraying process begins.

Alternatively, the spray chamber 18 has a closable opening 22 for gas exchange with the atmosphere. This serves to regulate the pressure in the spray chamber 18 and the aerosol flow through the spray chamber 18. This closable opening 22 can also be used to feed a sample into the spray chamber 18 so that the sample can be sprayed. The sample can also be fed into the chamber via another opening.

In a further embodiment, the spray chamber 18 of the atomizer system has a sample holder 19 for holding a sample to be sprayed. In a further embodiment, this can be rotated with a drive system, for example an electric motor. For example, it is set in rotation during the aerosol emission, for example when spraying the sample.

In addition, in one embodiment, the sample holder is located on a height-adjustable spacer 20, so that a specific distance between the sample and the nozzle 17 can be set.

In the context of this invention, a sample is any organic or inorganic body, a solid, gel, tissue or at least one cell. Using the atomizer system according to the invention, a large number of samples can be sprayed with a uniform aerosol stream containing particles smaller than 10 µm, so that a wide range of possible uses in technology and medicine is available.

One use is to coat a sample for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry.

Another use is the targeted coating of a sample to change its technical properties. This change can be, for example, an increase in chemical or mechanical resilience, a change in electrical conductivity and/or optical properties.

What is particularly advantageous about the atomizer system according to the invention is the spray chamber 18 designed as a resonance body. It ensures a uniform aerosol flow with particles smaller than 10 μm and stabilizes the aerosol so that the individual drops do not fuse with one another. 6 compares the atomizer system according to the invention with spray chamber 18 ( 6b) with another device without a spray chamber ( 6a) .

• - Regelung der Flussrate der Flüssigkeitszufuhr über den Flussratenregler 14 und Flüssigkeitszuleitung 2b
• - Regelung der Gaszufuhr über den Gasmassenflussregler 13 und Gaszuleitung 2a
• - die Sprühkammergeometrie mit dem Sprühkammerwinkel beta (Strömungsprofil und akustische Resonanz)
• - die Bewegungsart und -geschwindigkeit des Probenhalters

What is particularly advantageous about the atomizer system according to the invention is that the following parameters can be optimally adjusted for spraying a sample with a uniform aerosol stream with particles smaller than 10 µm:

• - Control of the flow rate of the liquid supply via the flow rate controller 14 and liquid supply line 2b
• - Control of the gas supply via the gas mass flow controller 13 and gas supply line 2a
• - the spray chamber geometry with the spray chamber angle beta (flow profile and acoustic resonance)
• - the type and speed of movement of the sample holder

• - der Innenquerschnitt und Material, Geometrie der Öffnung mit Düsenwinkel alpha,
• - der Querschnitt der Gaszuleitung 2a sowie dessen Geometrie und Oberflächenbeschaffenheit,
• - der Gasdruck sowie der Querschnitt des Gasreservoirs

Furthermore, the significant physical parameters of the spray head 1 or the nozzle 17 are realized particularly advantageously. These are:

• - the internal cross section and material, geometry of the opening with nozzle angle alpha,
• - the cross section of the gas supply line 2a as well as its geometry and surface quality,
• - the gas pressure and the cross section of the gas reservoir

wobei die dimensionslose Ausflussfunktion Psi die Massenstromdichte (rho(G) u) beschreibt: $$Psi=\frac{rh{o}_{G}u}{\sqrt{2p_{G0}rho\left(G_0\right)}}$$

The gas mass flow emerging at the diameter d of the cross section of the nozzle 17 is approximately: $m_G=\frac{pi\cdot {\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="DE102013019441B4\_0017.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}{4}{p}_{G0}\sqrt{\frac{2}{R{T}_0}}Psi$

where the dimensionless outflow function Psi describes the mass flow density (rho(G) u): $$Psi=\frac{rH{O}_{G}u}{\sqrt{2p_{G0}rHO\left(G_0\right)}}$$

The index 0 denotes the condition at the point of greatest expansion of the gas supply line 2a in the spray head 1. The pressure ratio reaches the critical value when the speed of sound is reached at the mouth. For air this results in an amount of approximately Psi ≈ 0.484. The positioning of the spray chamber 18 to the gas supply line 2a (influences, in addition to the surface tension of the sprayed aerosol and the gas composition, the drop formation or drop break-off and thus the length of the connected jet core. It is particularly crucial in connection with the spray head geometry in the atomization process that begins.

das auf Normdruck von Luft und Wasser bezogene dimensionslose Dichteverhältnis, $rho\prime =\sqrt{\frac{rh{o}_G}{rh{o}_{Luft}}\frac{rho}{rh{o}_{Wasser}}}$

und der Einfluss der Oberflächenspannung (sigma) sowie der dynamischen Viskosität (eta), $ny=\frac{sigm{a}_{Wasser}}{sigma}{\left(\frac{eta}{et{a}_{Wasser}}{\left(\frac{rho}{rh{o}_{Wasser}}\right)}^2\right)}^{1/3}$

der Fluide zu bestimmen. Das Massestromverhältnis wirkt sich auf die Schallgeschwindigkeit an der Düsenmündung aus. Diese kann ggf. deutlich unter der Schallgeschwindigkeit in den reinen Bezugsfluiden liegen, d.h. c{Wasser} ≈ 1500 m/s, c{Luft} ≈ 330 m/s. Im Rahmen der Testphase des erfindungsgemäßen Zerstäubersystems sind hierzu Experimente mit einem, unmittelbar an der Düsenmündung angebrachten, Kondensatormikrophon durchgeführt worden. Diese belegen eine erkennbare Drift im Frequenzspektrum, sobald das Massenstromverhältnis sprunghaft verändert wird. Die Sprühkammer 18 wirkt dabei als akustischer Resonator. Aus der Kombination einer Zweistoff-Düse mit einem akustischen Resonator können die sehr kleinen Tropfendurchmesser, die i.d.R. kleiner 10 µm ausfallen als über Gleichungen der Düsencharakterisierung berechnet wird, erklärt werden.In order to be able to adequately characterize two-component atomization, the flow shape(s) that form must be known at least to some extent. Here is the dimensionless mass flow ratio of the gas to the total mass flow, $\dot{x}=\frac{{\dot{m}}_G}{m_G+\dot{m}}$

the dimensionless density ratio related to the standard pressure of air and water, $rHO\prime =\sqrt{\frac{rH{O}_G}{rH{O}_{Luft}}\frac{rHO}{rH{O}_{Wasser}}}$

and the influence of surface tension (sigma) and dynamic viscosity (eta), $ny=\frac{siGm{a}_{Wasser}}{siGma}{\left(\frac{eta}{et{a}_{Wasser}}{\left(\frac{rHO}{rH{O}_{Wasser}}\right)}^2\right)}^{1/3}$

of the fluids. The mass flow ratio affects the speed of sound at the nozzle orifice. This can possibly be significantly below the speed of sound in the pure reference fluids, ie c{water} ≈ 1500 m/s, c{air} ≈ 330 m/s. As part of the test phase of the atomizer system according to the invention, experiments were carried out with a condenser microphone attached directly to the nozzle opening. These show a noticeable drift in the frequency spectrum as soon as the mass flow ratio changes suddenly. The spray chamber 18 acts as an acoustic resonator. The combination of a two-substance nozzle with an acoustic resonator can explain the very small drop diameters, which are usually smaller than 10 µm than is calculated using the nozzle characterization equations.

Mit c(W) dem dimensionslosen Widerstandsbeiwert. Die Oberflächenspannungskraft des Tropfens wirkt dabei seiner Zerteilung entgegen: F_sigma = pi · d_Tropfen - sigma Aus beiden Gleichungen ergibt sich dann das Stabilitätskriterium eines angeströmten statischen Tropfens: $\frac{rh{o}_G}{2}{\nu }_G^2\frac{pi\cdot d_{Tropfen}^2}{4}{c}_W=pi\cdot d_{Tropfen}\cdot sigma$

The primary drops generated in the atomizer system according to the invention can be further divided by the gas flow. This process is particularly suitable for obtaining a narrower size distribution. For the sake of simplicity, we first consider a resting (ideally) spherical drop on which a gas stream acts. The drop provides a so-called aerodynamic resistance force to the gas flow: $F_W=\frac{rH{O}_{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="DE102013019441B4\_0017.png"\; state="\{\{state\}\}">G</figure-callout>}}}{2}{\nu }_G^2\frac{pi\cdot d_{TrOpfen}}{4}{c}_W$

With c(W) the dimensionless drag coefficient. The surface tension force of the drop counteracts its fragmentation: F _sigma = pi d _drop - sigma The stability criterion of a static drop with flow results from both equations: $\frac{rH{O}_{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="DE102013019441B4\_0017.png"\; state="\{\{state\}\}">G</figure-callout>}}}{2}{\nu }_G^2\frac{pi\cdot d_{TrOp\mathrm{<figure-callout\; id="2"\; label="f\; e\; n"\; filenames="DE102013019441B4\_0017.png"\; state="\{\{state\}\}">f</figure-callout>}en}^2}{4}{c}_W=pi\cdot d_{TrOpfen}\cdot siGma$

Sinnvoller Weise wird die Stabilitätsbetrachtung in realen Aerosolen auf die kritische Relativgeschwindigkeit (d.h. auch der Tropfen bewegt sich) und einen kritischen Tropfendurchmesser bezogen: ${\nu }_{kritisch}=\sqrt{\frac{8sigma}{c_{W}rh{o}_G{d}_{Tropfen}}}$

$$d_{kritisch}=\frac{8sigma}{c_{W}rh{o}_G{\nu }_{relativ}^2}.$$

Ratios are defined. These are helpful for a more detailed characterization. On the one hand, this is the so-called gas Weber number: $$W{e}_G\equiv \frac{rH{O}_G{\nu }_G^2{d}_{TrOpfen}}{siGma}=\frac{\mathrm{8th}}{c_W.}$$

It makes sense to consider the stability in real aerosols based on the critical relative speed (i.e. the drop also moves) and a critical drop diameter: ${\nu }_{kritiscH}=\sqrt{\frac{\mathrm{8th}siGma}{c_{W}rH{O}_G{d}_{TrOpfen}}}$

$$d_{kritiscH}=\frac{\mathrm{8th}siGma}{c_{W}rH{O}_G{\nu }_{relativ}^2}.$$

Empirisch wird dann eine kritische Gas-Weberzahl gefunden, bei deren Überschreiten ein sekundärer Tropfenzerfall erwartet werden kann: $W{e}_G>\frac{8}{c_W}+14O{h}_T.$

Berücksichtigt werden muss, dass die angenommenen Ausgangsbedingungen über die Tropfengröße und die Relativgeschwindigkeit im Verlauf der Sprühnebelbildung nicht konstant sind.In order to take the liquid viscosity and vibration influences into account, the Ohnesorge number is also used: $O{H}_T=\frac{eta}{\sqrt{siGma\cdot rHO\cdot d_{TrOpfen}}}.$

Empirically, a critical gas Weber number is then found, if it is exceeded, secondary droplet decay can be expected: $W{e}_G>\frac{\mathrm{8th}}{c_W}+14O{H}_T.$

It must be taken into account that the assumed initial conditions regarding the droplet size and the relative speed are not constant in the course of the spray mist formation.

The time required for a droplet to break down can also be estimated: $t_{Zerfall}\approx 2.8\frac{d_{TrOpfen}}{{\nu }_{relativ}}\sqrt{\frac{rHO}{rH{O}_G}}.$

Two-fluid nozzles with an internal mixture are known to have a tendency to form what is known as overspray. Because the drops sometimes become very small, the mass of the drops decreases and the relative speed approaches zero. This is a phenomenon of microfluidics. The drops then follow the formed gas flow and are not only transported onto the surface of a sample to be coated. In the atomizer system according to the invention, the majority of the aerosol therefore remains as overspray on the walls of the spray chamber. On the one hand, the proportion of overspray is then lost when spraying a sample, for example, but on the other hand, it is a clear quality feature of small drops under 10 µm with a narrow size distribution in the aerosol. This then creates a flat distribution of the amount of aerosol over the surface of the sample to be sprayed.

An important advantage of the atomizer system according to the invention is that the aerosol drops are still sufficiently moist when they hit the sample in order, for example, to release analytes from the sample and to absorb these analytes as they dry and crystallize or to create a stable and/or uniform aerosol stream with particles smaller than 10 µm to spray.

[Examples]

• 1: den schematischen Aufbau des erfindunsgemäßen Zerstäubersystems
• 2: den schematischen Aufbau des Sprühkopfes 1
• 3: den schematischen Aufbau eines beispielhaften Zerstäubersystems
• 4: den schematischen Aufbau einer Sprühkopfspitze mit Düse 17
• 5: den schematischen Aufbau eines beispielhaften Zerstäubersystems
• 6 Vergleich Zerstäubersystem mit und ohne Sprühkammer 18
• 7 eine Anwendung im technischen Bereich, wobei die Probe ein Wafer ist
• 8 eine Anwendung im biotechnologischen Bereich, wobei die Probe hefezellen sind

Preferred exemplary embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings. Show:

• 1 : the schematic structure of the atomizer system according to the invention
• 2 : the schematic structure of the spray head 1
• 3 : the schematic structure of an exemplary atomizer system
• 4 : the schematic structure of a spray head tip with nozzle 17
• 5 : the schematic structure of an exemplary atomizer system
• 6 Comparison of atomizer system with and without spray chamber 18
• 7 an application in the technical field, where the sample is a wafer
• 8th an application in the biotechnological field, where the sample is yeast cells

Further aspects and embodiments of the present invention are disclosed in the following description. Reference is also made to the attached drawings.

1 : schematic structure of the atomizer system according to the invention

In the atomizer system according to the invention, a liquid is introduced into the spray head 1 via the liquid supply line 2b. The control takes place via the flow rate controller 14. Regardless of this, gas is introduced into the spray head 1 via the gas supply line 2a. The gas flow is controlled via the gas mass flow controller 13. The gas introduction can also take place before or after the liquid supply. For aerosol formation, however, it must at least occur during the liquid supply, otherwise no aerosol formation occurs. The aerosol formation takes place in the mixing area 10 of the spray head 1. The spray head 1 has a nozzle 17 through which the aerosol drops 40 can leave the spray head 1. According to the invention, the spray head 1 has a tapering area towards this opening, so that a nozzle 17 is created. This creates an aerosol that leaves the spray head 1 through the nozzle 17 and enters the spray chamber 18.

2 shows a concrete possible embodiment of the spray head 1. This has a gas supply line 2a through which gas is introduced into the spray head 1. The liquid supply takes place here via a liquid supply line 2b.

3 shows an embodiment variant of the atomizer system according to the invention.

It includes the spray head 1 and the spray chamber 18. The gas supply takes place via a gas mass flow controller 13 and the gas supply 2a into the spray head 1. The gas can also be tempered, for example heated or cooled, via an optional thermocouple 11.

In addition, the liquid to be atomized is supplied, for example, via a liquid feed 2b from a liquid reservoir 16, e.g. a syringe, via a flow rate regulator with flow rate meter 14 and a hose connection adapter 6 into the spray head 1. The liquid can be tempered, e.g. heated or cooled, via an optional thermocouple 31.

After atomization, the aerosols leave the spray head 1 via the nozzle 17 and enter the spray chamber 18. This includes a sample holder 19 suitable for holding a sample, a spacer 20 and a drive system 21.

Within the spray chamber 18, the aerosols fall onto the sample holder 19 provided with a sample. This is connected to a drive system 21 via a spacer 20 and can be set in rotation by this. Furthermore, the spray chamber 18 also has closable openings 22. These serve to control the gas flow through the spray chamber 18.

• 1 : 75 mm bis 85 mm,
• 52: 120 µm bis 140 µm,
• 51: 470 µm bis 490 µm,
• 50: 790 µm bis 810 µm,
• 50a: ist kleiner gleich ((50)-(51))/2,
• 61: 2,25 mm bis 2,75 mm (innere Mischung),
• 55: 5,5 cm bis 6,5cm,

4 shows a specific embodiment of the tip of a spray head 1 with the nozzle 17. When emerging from the gas supply line 2a, the emerging aerosol drop 40 is atomized by the inflowing gas. Since this takes place directly above the nozzle 17, its geometric shape is of great importance. What is important here is the nozzle angle α. This is 40° to 80°, preferably 50° to 70°. This nozzle angle can be adjusted, for example using a small servomotor (not shown). In a specific exemplary embodiment, the system has the following dimensions.

• 1: 75mm to 85mm,
• 52: 120 µm to 140 µm,
• 51: 470 µm to 490 µm,
• 50: 790 µm to 810 µm,
• 50a: is less than or equal to ((50)-(51))/2,
• 61: 2.25mm to 2.75mm (inner mix),
• 55: 5.5cm to 6.5cm,

5 shows the atomizer system according to the invention with the spray chamber 18 designed as an acoustic resonance body.

The ratio of chamber width 56 to the diameter of the sample area to be sprayed is approximately 3 to 1 in the area up to the sample surface to be sprayed. The chamber walls in this area are rectangular, as a round wall design has different properties. The wall is preferably made of a chemically resistant plastic, for example polyethylene terephthalate (PET). Immediately below the surface to be sprayed, the chamber walls 69, 60 taper to a diameter of 57. The ratio of diameter 57 to the diameter of the sample surface to be sprayed is 1.4 to 1. The area of the taper 59, 60 is round.

The spray chamber angle beta β, which characterizes this taper, is approximately 30° to 60°, preferably 40° to 50°

The closable openings 22 on the bottom of the chamber (adjacent to diameter 57) are dimensioned so that a sufficiently large gas flow is achieved. A chemically inert gas such as nitrogen, helium or CO ₂ is used as the supplied gas for atomization.

6 shows the degree of coverage of a sample with aerosol drops in an atomizer system with and without spray chamber 18. Here it is clear that the use of the spray chamber 18 leads to a uniform aerosol flow over the area with particles smaller than 10 µm.

In one possible embodiment, the atomizer system is used for comprehensive and homogeneous matrix coating for matrix-assisted laser desorption/ionization (MALDI) of physically and chemically very different surfaces. The following part of the description refers to this application. However, this is only to be understood as an example. It is possible for the person skilled in the art to transfer this teaching to other areas of application, for example technology.

The spraying of various samples, for example native and biological “surfaces”, metallic surfaces, glass surfaces (BK07) and silicon wafer surfaces, was tested for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The size of the resulting particles corresponds to the droplet size of the aerosol. It is possible to use the substance 2,5-dihydroxybenzoic acid (DHB), which is very frequently used in MALDI analysis, as a matrix to produce particle sizes of on average three to five micrometers over an area of approximately 1 to 10, preferably approximately 3 cm ² applied to a metallic surface. Comparative measurements with devices from the prior art without a spray chamber 18 show that the particles on glass surfaces have a size of approximately 15 micrometers with a relatively broad size distribution (see also 6 , middle figure). The atomizer system according to the invention, on the other hand, enables particle sizes below 10 μm. After optimizing the relevant process parameters and regulating the flow rates (volume and mass flow of the fluids), the reproducibility of these results is given with a statistical one-sigma probability or an RSD of 5%. It is possible to achieve an average particle size of approx. 3 µm. Test results obtained with the possibility of active feedback on the actual flow rates suggest that with automatic control of the flow rates of the fluids, the average particle size of the substance 2,5-DHB can also be reduced to below 3 µm.

It is of central importance for the subsequent MALDI-MS analysis that although these relatively small particles are generated, all native biological surfaces form a contact efficiency with the matrix that is sufficient for phospholipids and peptides. The lateral migration of analytes proved to be largely insignificant at the preparation scale (0.25 µm to 2 µm), i.e. positioning artifacts are more likely to be attributed to effects such as secondary deposition of sample material or disruptions or fluctuations in the movement sequences within the grid mechanics when changing the sample location.

7 shows, as exemplary embodiment 1, the matrix preparation of the line structures of the etched Si wafer. In the ion intensity distribution image in part a), the line structures filled with matrix can be seen. Partial figure b) shows a fluorescence image of the matrix coating produced by spray preparation. Partial figure c) shows the ion intensity distribution image of the matrix signal m/z 273 u of the 2.5-DHB matrix applied to the etched silicon wafer by spray preparation.

shows as an exemplary embodiment 2, measurements of the lipid head group of the yeast cells. Partial figure a) shows yeast cells in suspension in a bright field transmitted light image with visible light. Partial b) shows the lipid head group m/z 184 u after spray preparation in an ion intensity distribution image (in a different section than in part a). Individual yeast cells are clearly shown. The lateral size of the yeast cells is between 3 µm and 15 µm. The preparation was produced using the atomizer system according to the invention and the matrix 2,5-DHB. The bright field transmitted light image is not the same area as the ion intensity distribution image. This only serves for structure and size orientation.

The atomizer system according to the invention is, as shown in exemplary embodiment 2, also successfully used on biological tissue samples and cells, so that analysis of peptides is possible even on a single-digit micrometer scale.

List of reference symbols:

1

spray nozzle

2a

Gas supply line

2 B

Liquid supply line

6

Hose connection adapter

10

Mixing area

11.31

Thermocouple

12

Capillary guidance

13

Gas mass flow controller

14

Liquid flow rate controller

15.25

pump

16

gas reservoir

26

Fluid reservoir

17

jet

18

Spray chamber

19

Sample holder

20

Spacers

21

Drive system

22

lockable opening

31

Liquid mass meter

40

Aerosol

50

790 µm to 810 µm

50a

is less than or equal to ((50)-(51))/2

51

470 µm to 490 µm

52

120 µm to 140 µm

55

5.5cm to 6.5cm

56

Chamber width

57

diameter

59.60

Rejuvenation of the chamber walls

61

2.25mm to 2.75mm

100

Atomizer system

α

Nozzle angle

β

Spray chamber angle

Claims (8)

Atomizer system (100) having a spray chamber (18) and a spray head (1) with a gas supply line (2a) and with a liquid supply line (2b), the spray head (1) having a mixing area in its interior and being gas-tight with the spray chamber (18). is connected via a fastener, the spray head (1), a gas mass flow controller (13) and a flow rate controller (14) characterized in that the spray head (1) has a taper in a section facing the spray chamber (18), which forms a two-substance nozzle of internal mixture (17) and the spray chamber (18) has a tapered section on that of the nozzle (17) has the opposite section with a spray chamber angle β of 30 ° to 60 ° and thus acts as an acoustic resonance body. atomizer system Claim 1 characterized in that the spray head (1) on the nozzle (17) has a nozzle angle α of 40° to 80°. Atomizer system according to one of the preceding claims, characterized in that the spray head (1) has a sensor on the gas supply line (2a) for controlling the gas supply and/or has a sensor on the liquid supply line (2b) for controlling the liquid supply. Atomizer system according to one of the preceding claims, characterized in that the spray head (1) has a pump (15, 25) on the gas supply line (2a) and/or the liquid supply line (2b). Atomizer system according to one of the preceding claims, characterized in that the spray chamber (18) has at least one closable opening (22) for gas exchange with the atmosphere. Atomizer system according to one of the preceding claims, characterized in that the spray chamber (18) has a sample holder (19). Atomizer system according to one of the preceding claims, characterized in that the spray chamber (18) has a sample holder (19) with a spacer (20) for setting a specific distance of a sample to the nozzle (17). Use of an atomizer system according to one of the preceding claims for uniform coating of a sample.

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