DE202016102767U1 - Portable device for measuring volatile chemicals - Google Patents

Abstract

A portable device (100) for measuring volatile chemicals, comprising: - a housing (110); - A measuring attachment (10) connected to the housing (110), comprising a channel (11), and a detector layer (51) of a detector (50, 51) arranged in the portable device (100), wherein the detector (50, 51 ) is arranged to detect a volatile chemical substance in a detector layer (51) via the channel (11) can be supplied gaseous sample via a change in a fluorescence intensity of the detector layer (51), and - in the housing (110) arranged environmental sensor (30) fluidically coupled to the duct (11) and arranged to measure at least one factor that may contribute to cross sensitivity of the volatile chemical detector (50, 51).

Description

The present invention relates to a portable device for measuring volatile chemicals, in particular Volatile Organic Compounds (VOCs).

Using laboratory setups, volatile chemicals (VOCs), such as the most commonly used explosives, such as 2,4,6-trinitrotoluene (TNT), can be detected and even quantified using enrichment and desorption techniques with high sensitivity down to the ppm range. In this case, a molecularly imprinted polymer (MIP, "Molecular Imprinted Polymer"), e.g. compared to nitroaromatic compound-specific nanoscale polymer particles used. The gas containing the volatile chemicals, for example ambient air, is passed via hoses through an MIP filter by selectively absorbing the molecules of the substances to be detected. Subsequently, the molecules are desorbed and fed to a sensor unit.

However, the laboratory setups are relatively large and heavy and therefore often unsuitable for on-site detection of explosives, drugs and toxins.

However, easily manageable and portable detection devices capable of detecting these volatile chemicals quickly, reliably, and in sufficiently low concentration would be useful in many fields, e.g. in personal checks, for the surveillance or inspection of public buildings and transport, in the ammunition recovery service, as well as in the dog training, of great benefit.

In view of the above, the present invention proposes a portable device according to claim 1.

According to one embodiment, a portable device for measuring volatile chemical substances comprises a housing and a measuring attachment connected to the housing. The measuring attachment has a channel and a detector layer of a detector arranged in the portable device. The detector is configured to detect a volatile chemical in a gaseous sample supplied to the detector layer via the channel via a change in a fluorescence intensity of the detector layer. The housing further houses an environmental sensor fluidly coupled to the channel and configured to measure at least one quantity of influence that may contribute to cross sensitivity of the volatile chemical detector.

By combining the fluorescence-based detector with the environmental sensor, both a good measurement sensitivity and a high measurement reliability can be provided in a comparable small device, in particular with suitable channel guidance. By taking into account cross sensitivities, the false alarm rate of the highly sensitive fluorescence detection of the VOCs can be at least significantly reduced.

The portable device may be designed, in particular in the form of a measuring and testing head as a small mobile unit having a portable housing for receiving the various components, preferably in one hand can be held and typically has a handle, which may be formed, for example, as a pistol grip can.

Typically, the portable device has a mass of less than 1 kg.

In addition, the internal volume of the housing is typically at most 0.3 L, more typically at most 0.2 L.

The volume of the handle is typically at most 0.1L.

The term "volatile chemical" as used herein is intended to mean volatile organic compounds (VOCs) having a boiling temperature at normal pressure (101.3 kPa) up to about 300 ° C, especially in a range from about 0 ° C. to about 250 ° C. or 260 ° C. For example, the volatile chemical substance may be organic compounds having NO x groups, but depending on the fluorescent layer, other airborne substances may also be detected.

The at least one influencing variable which may contribute to cross-sensitivity is typically a concentration of a gas, for example the concentration of water vapor. However, which gas is involved depends typically on the VOC (s) to be detected, i. from the matched detector layer (s).

According to a further development, the environmental sensor is set up to measure two or even more influencing variables which can contribute to a cross sensitivity of the detector for the volatile chemical substance. This allows the False alarm rate further reduced and thus the reliability of the measurement can be increased accordingly.

For this purpose, the environmental sensor may, depending on the number of influencing variables for cross sensitivities to be measured, have one or more, e.g. three fluidically connected to the air channel resistance layers whose electrical resistance depends on the concentration of the influence. Typically, the resistive layer (s) are oxide layers.

Typically, the environmental sensor has a resistance measuring unit connected to the resistive layer (s).

From the measured respective resistance or the change in resistance when supplying the gaseous sample can be determined on a concentration of the influence quantity for cross-sensitivities. Such resistance measurements can be made compact and very sensitive. In this way, cross-sensitivities of the fluorescence measurement can be reliably and easily taken into account.

Due to the typically short supply of the gaseous sample to the environmental sensor, the measurement of the concentration of the influencing variable or the influencing variables can be carried out with particularly high accuracy, since any losses due to adsorption can be at least largely avoided.

Typically, the gaseous sample is guided by means of a pump from the detector layer to the environmental sensor. The pumping rate is typically in a range between about 30 and 100 mL / min.

In front of the detector layer, the channel typically has a funnel-shaped inlet providing a gaseous sample inlet, a non-heated portion, and a heated portion disposed between the funnel-shaped inlet and the unheated portion.

The typically arranged at least partially around the heated section around electric heater with a typical heat output of about 3 W to 5 W ensures that the VOCs to be measured can not be deposited on the walls of the channel and thus reach the detector layer. In addition, the heating can ensure stable temperature conditions at the detection layer, which can have a positive effect on the measurement accuracy and / or measuring sensitivity of the detector for the VOCs.

The channel and the heater are typically selected such that a heat gradient arises from the inlet opening to the detector layer. As a result, the detector layer can be operated in the optimum temperature range.

In addition, a swirling structure for swirling the gaseous sample may be arranged between the non-heated section of the channel and the detector layer. By means of the swirling structure, the gaseous sample can be well distributed on the detector layer and thereby swirled. Thus, a high accumulation of the substances to be detected on the surface of the detector layer can be achieved.

As a result of the swirling structure, the measuring accuracy and / or measuring sensitivity of the detector for the VOCs can likewise be increased.

Depending on the embodiment, the detector can detect the volatile chemical substance via a quenching or an increase in the fluorescence of the detector layer.

The measurement of a quenching of the fluorescence typically allows a higher detection sensitivity.

The measurement sensitivity for VOCs in gaseous samples such as air, which is achievable with the portable device for measuring volatile chemical substances, also referred to below as a portable VOC sensor unit, amounts to at least 10 pg / min. Thus, even with a concentration of less than 0.1 ppb (1 μg / L), VOCs can be detected in the typical pumping rates given above.

Typically, multiple volatile chemicals, e.g. various explosives or emitted by these VOCs, are detected in the supplied via the channel gaseous sample via a weakening or amplification of a respective fluorescence of the detector layer.

As a result, the range of applications of the portable VOC sensor unit can be significantly expanded.

Accordingly, the detector layer has fluorophores selected to selectively react with the VOC (s).

For example, the detector layer may be formed by one having a corresponding fluorescent dye layer deposited on a support of glass or a polymer.

In this case, the detector layer can have a plurality of regions or a plurality of partial layers, for example two Partial layers, with respective specific fluorophores for a VOC to be detected, for example an explosive, a drug or a toxin.

Since the measuring attachment is typically detachable, e.g. screwed, is connected to the housing, can be changed by changing the measuring attachment and the detector layer. This allows the easy change of different detector layers. In this case, either the entire measuring attachment can be exchanged or only the carrier which is exchangeably mounted in the measuring attachment in this embodiment and the detector layer. As a result, in each case the area of use of the portable VOC sensor unit can be further increased.

For detection, the fluorescence of the detector layer can be excited by means of a fluorescence unit arranged in the housing, which is typically designed to measure an intensity of the fluorescence or even a time profile of the intensity of the fluorescence.

For this purpose, the fluorescence unit has a light source, e.g. a laser diode, and a light detector, e.g. a photodiode, a CCD line or a CCD camera.

Typically, the optical design of the detector is designed for a fluorescence reflectance measurement.

In addition, the fluorescence unit typically has a monochromator for selecting the excitation wavelength and / or the detection wavelength.

In order to shield the light detector from stray light and to prevent decoupling of the excitation light, a light shutter made of a light-absorbing material is typically additionally arranged in the channel.

The measurement may be controlled by a control unit located outside, inside, or at least partially within the housing, which is connected to the detector and the environmental sensor.

Typically, the controller is configured to determine a concentration of the VOC (s) in the sample using the change in fluorescence intensity, and to use the influence (s) in determining the concentration of the VOC (s).

In addition, the control unit is typically configured to operate the portable VOC sensor unit as a flowmeter for VOCs.

In this case, the controlled by the control unit measuring method can be implemented as a reflection measurement method with continuous or pulse-shaped excitation.

Typically, the portable VOC sensor unit additionally includes a switch for triggering a measurement connected to the control unit and a display unit connected to the control unit for outputting the measurement result.

The display unit is typically attached to the housing. It can be designed as a display and / or comprise one or more LEDs.

For example, the flashing of a green LED may indicate that no VOCs have been detected.

Similarly, the flashing of a red LED may indicate that one or more VOCs have been detected.

In this way, VOCs can be detected quickly and safely even in dangerous situations or in poor visibility.

Alternatively or additionally, the detection of VOCs or even their concentration can be acoustically output, e.g. via a speaker connected to the control unit.

The switch can be fastened to the handle. This allows a good operability.

In addition, an internal battery or a battery for power supply can be arranged in the handle.

Furthermore, a connection for a power supply, in particular a 12 V power supply and / or a plug for data transmission, which can also be used for programming the control unit, can be arranged on the housing or on the handle.

The above-described embodiments may be arbitrarily combined with each other.

Further advantageous embodiments, details, aspects and features of the present invention will become apparent from the dependent claims, the description and the accompanying drawings. It shows:

1A a schematic cross section of a measuring device for portable device for Measuring volatile chemicals according to an embodiment;

1B a schematic view of a portable device for measuring volatile chemical substances with in 1A illustrated measuring attachment according to an embodiment; and

2 a perspective view of in 1B represented portable device for measuring volatile chemical substances.

In the figures, like reference numerals designate corresponding parts accordingly.

1A shows a schematic central cross section of a measuring attachment 10 and 1B a schematic view of a portable device 100 for measuring volatile chemicals with the measuring attachment 10 , For clarity, in 1B on a representation of internal details of the measuring attachment 10 Instead of a typical supervision of the measuring attachment 10 shown.

How better the in 2 shown in perspective view, is the portable VOC sensor unit 100 in the exemplary embodiment as a small mobile unit with a housing 110 that in a handle 120 goes over and on which the measuring attachment 10 is attached, trained.

The housing 110 and the handle 120 can be made of metal and / or plastic. On the case 110 are an ad 105 and four exemplary pushbuttons 104 placed. On the display 105 the measured values and / or respective operating setting can be displayed. By means of the pushbuttons 104 The operating setting can be changed and the measurement can be started and stopped. But a switch or a push button to start and stop the measurement can also be on the handle 120 be arranged.

In the 1A . 1B is the flow of the measurement by means of a housing 110 arranged pump 40 aspirated sample air represented by the dot-dashed arrows.

The sample air passes through a funnel-shaped inlet during operation 11a in a heated section 11b . 11c a channel 11 with a typically substantially rotationally symmetric wall 12 one. The heated section 11b . 11c can over a the channel section 11b . 11c external electric heating 14 be heated. In order to be able to set desired temperature profiles (in the flow direction) well and to facilitate a desired tempering, the wall is made 12 typically made of a metal, eg brass, steel or aluminum.

In a (downstream) rear section 11c of the heated section 11b . 11c is the channel 11 widened perpendicular to the flow direction. In this section is a light aperture 16 having a larger outer diameter than the inner diameter of the front portion 11b of the heated section 11b . 11c arranged.

After leaving the heated section 11b . 11c The sample air is passed through a non-heated section 11d and a swirling structure 17 a fluorescence-sensitive detector layer 51 fed.

As explained above, the detector layer 51 one or more fluorophores specifically interacting with VOCs.

If the detector layer 51 have different fluorophores, these are typically each arranged in separate areas or sub-layers.

By means of a housing 110 arranged fluorescence unit 50 as shown by the dotted arrow in 1B shown, a fluorescence of the detector layer 51 and can measure an intensity of fluorescence or even a time course of the intensity of the fluorescence, VOCs can be detected.

Via an external connection 20a (eg a hose or pipe) and a first internal fluid connection 20b can be at the detector layer 51 Passed sample air on the shortest possible way an environmental sensor 30 for measuring the concentration of one or more gases leading to cross sensitivities of the fluorescence detector 50 . 51 contribute can be supplied.

As explained above, the environmental sensor 30 typically one or more with the air duct 11 fluidically bonded oxide layers whose respective resistance depends on the concentration of a gas.

In the exemplary embodiment, the environmental sensor is 30 fluidically by means of a second internal fluid connection 20b with the pump 40 coupled. By means of the pump 40 can sample air from the environmental sensor 30 sucked off and via a third internal fluid connection 20d out of the case 110 be pumped.

Typically, inside the case 110 a control unit 60 arranged with the detector 50 , the environmental sensor 30 , and the pump 40 connected and controls.

The control unit 60 can also take over the functions of the evaluation of the measurements, ie be implemented as a combined control / evaluation unit.

Alternatively or additionally, the evaluation of the measured data can take place wholly or partly externally.

For rapid on-site detection, an internal evaluation of the measured data takes place, in particular a consideration of the cross-sensitivities, and the output of important measurement results on the display. The portable VOC sensor unit is easy to operate (e.g., via push buttons), variable, and makes it possible to detect VOCs quickly, with very low false alarm rates and in a sufficiently low concentration. In addition, it is relatively inexpensive to produce. Therefore, it can not only be used for personal checks, for monitoring or checking of public buildings and transport, in the ammunition recovery service, as well as in the dog training, but also help to improve safety in everyday laboratory everyday cost.

The present invention has been explained with reference to exemplary embodiments. These embodiments should by no means be construed as limiting the present invention. The following claims are a first, non-binding attempt to broadly define the invention.

Claims (30)

Portable device ( 100 ) for measuring volatile chemicals, comprising: - a housing ( 110 ); - one with the housing ( 110 ) ( 10 ), having a channel ( 11 ), and a detector layer ( 51 ) in the portable device ( 100 ) arranged detector ( 50 . 51 ), the detector ( 50 . 51 ), a volatile chemical in one of the detector layer ( 51 ) over the canal ( 11 ) deliverable gaseous sample via a change in a fluorescence intensity of the detector layer ( 51 ), and - one in the housing ( 110 ) arranged environmental sensor ( 30 ), which fluidly with the channel ( 11 ) and is set up to measure at least one influencing variable which leads to a cross-sensitivity of the detector ( 50 . 51 ) can contribute to the volatile chemical. Contraption ( 100 ) according to claim 1, wherein the at least one influencing variable is a concentration of a gas in the gaseous sample. Contraption ( 100 ) according to claim 1 or 2, wherein the environmental sensor ( 30 ) is arranged to measure at least one further influencing variable, which leads to a further cross sensitivity of the detector ( 50 . 51 ) can contribute to the volatile chemical. Contraption ( 100 ) according to one of the preceding claims, wherein the environmental sensor ( 30 ) at least one with the air duct ( 11 ) has a fluidically connected oxide layer and is set up to measure an electrical resistance of the at least one oxide layer, and / or wherein the environmental sensor ( 30 ) three with the air duct ( 11 ) has fluidically connected oxide layers and is arranged to measure a respective electrical resistance of the three oxide layer. Contraption ( 100 ) according to one of the preceding claims, wherein the detector ( 50 . 51 ) is designed to contain several volatile chemical substances in the 11 ) supplied gaseous sample via a weakening or amplification of a respective fluorescence of the detector layer ( 51 ) to detect. Contraption ( 100 ) according to one of the preceding claims, wherein the detector layer ( 51 ) is designed so that an interaction of the volatile chemical substance with the detector layer ( 51 ) to a reduction of the fluorescence intensity of the detector layer ( 51 ), wherein the volatile chemical substance has a NOx group, and / or or wherein the volatile chemical substance is an explosive, a narcotic or a toxin. Contraption ( 100 ) according to one of the preceding claims, wherein the detector layer ( 51 ) And / or wherein the fluorophores are selected to react selectively with the volatile chemical. Contraption ( 100 ) according to one of the preceding claims, wherein the detector layer ( 51 ) has multiple regions and / or multiple sublayers, each having different fluorophores. Contraption ( 100 ) according to claim 8, wherein the detector layer comprises two partial layers. Contraption ( 100 ) according to one of the preceding claims, further comprising a housing ( 110 ) arranged pump ( 40 ), which is arranged so that the gaseous sample to the detector layer ( 51 ) and / or to the environmental sensor ( 30 ) can be pumped. Contraption ( 100 ) according to claim 10, wherein an adjustable pumping rate of the pump is in a range of 30 mL / min and 100 mL / min. Contraption ( 100 ) according to one of the preceding claims, wherein the channel ( 11 ) a funnel-shaped inlet ( 11a ), a non-heated section ( 11d ) and / or between the funnel-shaped inlet ( 11a ) and the unheated section ( 11d ) arranged heated section ( 11b . 11c ) having. Contraption ( 100 ) according to one of the preceding claims, further comprising an adjacent to the channel ( 11 ), in particular at least partially around the heated section ( 11b . 11c ) around ( 14 ). Contraption ( 100 ) according to claim 13, wherein the heater is an electric heater and / or wherein the heater has a power of at least 3 W and / or at most 5 W. Contraption ( 100 ) according to one of the preceding claims, further comprising one in the channel ( 11 ) arranged light aperture ( 16 ). Contraption ( 100 ) according to claim 15, wherein the light aperture ( 16 ) in an expanded section ( 11c ) of the air duct ( 11 ), and / or wherein the light aperture ( 16 ) has a larger diameter than an adjacent section ( 11b . 11d ) of the air duct ( 11 ). Contraption ( 100 ) according to one of the preceding claims, wherein the detector has a housing (in 110 ) arranged fluorescence unit ( 50 ), which is set up, a fluorescence of the detector layer ( 51 ) to measure an intensity of the fluorescence and / or to measure a time course of the intensity of the fluorescence. Contraption ( 100 ) according to claim 17, wherein the fluorescence unit ( 50 ) comprises a light source, a light detector and / or a monochromator. Contraption ( 100 ) according to one of the preceding claims, further comprising a swirling structure ( 17 ) for swirling the gaseous sample in front of the detector layer ( 51 ). Contraption ( 100 ) according to one of the preceding claims, further comprising an outside or at least partially disposed within the housing control unit ( 60 ) connected to the detector ( 50 ) and the environmental sensor ( 30 ) connected is. Contraption ( 100 ) according to claim 20, wherein the control unit ( 60 ) is adapted to detect, using the change in fluorescence intensity, a presence of the volatile chemical in the gaseous sample and / or to determine a concentration of the volatile chemical in the gaseous sample. Contraption ( 100 ) according to claim 21, wherein the control unit ( 60 ) is adapted to use the influence in detecting the volatile chemical in the gaseous sample and / or in determining the concentration of the volatile chemical in the gaseous sample. Contraption ( 100 ) according to claim 21 or 22, further comprising one with the control unit ( 60 ) connected display unit, in particular a display ( 105 ) and / or an LED, a speaker connected to the control unit, and / or one with the control unit ( 60 ) connected switch or button ( 104 ) to trigger a measurement. Contraption ( 100 ) according to one of claims 20 to 23, wherein the control unit ( 60 ), the device ( 100 ) as a flow meter for the volatile chemical substance. Contraption ( 100 ) according to one of the preceding claims, comprising a measurement sensitivity for the volatile chemical substance of at least 0.1 μg / L. Contraption ( 100 ) according to one of the preceding claims, wherein the housing ( 110 ) and / or the device ( 100 ) is portable with one hand. Contraption ( 100 ) according to one of the preceding claims, wherein the device ( 100 ) has a mass of less than 1 kg, and / or wherein the housing ( 110 ) has an internal volume of at most 0.3 L, preferably of at most 0.2 L. Contraption ( 100 ) according to one of the preceding claims, wherein the housing ( 110 ) a handle ( 120 ) or with a handle ( 120 ), and / or wherein the handle has a volume of at most 0.1 L. Contraption ( 100 ) according to one of the preceding claims, wherein the measuring attachment ( 10 ) detachable with the housing ( 110 ) connected is. Contraption ( 100 ) according to one of the preceding claims, wherein in the housing ( 110 ) or in the handle ( 120 ) an internal battery is arranged, and / or wherein on the housing ( 110 ) or the handle ( 120 ) a connection for a power supply, in particular a 12 V power supply and / or a connector for data transmission is arranged.

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