DEVICE FOR HOLDING A TARGET GAS

Abstract

A device for holding a target gas comprises a compartment configured to hold the target gas. The device further comprises a gas generator configured and arranged to release the target gas in the compartment in response to a control signal. The device further comprises a reference sensor sensitive to the target gas and arranged to supply a sensor signal representing a concentration of the target gas in the compartment. A control unit is provided and configured to control the release of the target gas from the gas generator by way of the control signal, dependent on the sensor signal. The gas generator and the reference sensor are arranged in the compartment.

Claims

1. Device for holding a target gas, comprising a compartment configured to hold the target gas, a gas generator configured and arranged to thermally release the target gas in the compartment in response to a control signal, wherein the gas generator comprises a material emitting the target gas in response to thermal activation, a reference sensor sensitive to the target gas and arranged to supply a sensor signal representing a concentration of the target gas in the compartment, a control unit configured to control the release of the target gas from the gas generator by way of the control signal, dependent on the sensor signal, wherein the gas generator and the reference sensor are arranged in the compartment.

2. Device according to claim 1, wherein the material is configured to be decomposed in response to the thermal activation thereby emitting the target gas.

3. Device according to claim 1, wherein the material is configured to generate the target gas by desorption in response to the thermal activation.

4. Device according to claim 1, configured to solely increase the target gas concentration in the compartment by way of activating the gas generator to release the target gas in the compartment.

5. Device according to claim 1, wherein the compartment is sealed from an exterior.

6. Device according to claim 5, wherein one or more walls defining the compartment comprises one or more electrical connections arranged in one or more gas-tight feedthroughs for electrically connecting one or more of components arranged in the compartment from the exterior.

7. Device according to claim 1, wherein a volume defined by the compartment is less than 1000 ml.

8. Device according to claim 1, wherein the target gas is O.sub.2.

9. Device according to claim 8, wherein the material includes ZnO.sub.2.

10. Device according to claim 1, wherein the material has the form of one or more of powder, sand, grains, pressed pellets and granulate.

11. Device according to claim 1, wherein the gas generator comprises an electrical heater for enabling the thermal activation of the material and wherein the control signal is configured to control the electrical heater.

12. Device according to claim 11, comprising a temperature sensor arranged to directly or indirectly measure the temperature of the electrical heater, wherein the control unit is configured to adjust a heating of the electrical heater in response to the determined temperature of the electrical heater.

13. Device according to claim 12, wherein the temperature sensor is arranged outside the compartment and is attached to a wall of the compartment or is arranged at a location thermally coupled the gas generator.

14. Device according to claim 11, comprising a probe current or probe voltage applied to the electrical heater for determining a temperature of the electrical heater, wherein the control unit is configured to adjust a heating of the electrical heater in response to the determined temperature of the electrical heater.

15. Device according to claim 1, wherein the control unit is configured to control a target gas concentration in the compartment to a constant value in a feedback loop, wherein the control unit comprises a comparator configured to compare the sensed target gas concentration supplied by the sensor signal with the constant value, wherein the control unit comprises a controller configured to define the control signal subject to a difference between the sensed target gas concentration and the constant value as provided by the comparator.

16. Device according to claim 15, wherein the controller is a PI controller.

17. Device according to claim 1, wherein the reference sensor is a thermal gas sensor.

18. Device according to claim 1, wherein the reference sensor is sensitive to at least one background gas different to the target gas and is arranged to supply one of a background gas sensor signal representing a concentration of the background gas in the compartment, or a signal indicative of a mixing ratio between the target gas and the background gas.

19. Method for controlling a concentration of a target gas in a compartment, comprising sensing a concentration of the target gas in the compartment by means of a reference sensor arranged in the compartment, dependent on the sensed concentration of the target gas controlling a gas generator arranged in the compartment configured to thermally release the target gas in the compartment, the gas generator comprising a material emitting the target gas in response to thermal activation.

20. Method according to claim 19, comprising placing a unit to be tested in the compartment, wherein the unit is sensitive to the target gas, releasing the target gas in the compartment, and continuing with the sensing and the controlling step, and iterating the sensing and the controlling step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The invention will be better understood and objects other than those set forth above will become apparent from the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:

[0063] FIG. 1 illustrates a device according to an embodiment of the present invention;

[0064] FIG. 2 illustrates a device according to an embodiment of the present invention;

[0065] FIG. 3 illustrates a feedback control loop as implemented in a device according to an embodiment of the present invention;

[0066] FIG. 4 illustrates a flow chart illustrating a method according to an embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

[0067] FIG. 1 illustrates a device for holding a target gas according to an embodiment of the present invention. The device comprises a compartment 1. The compartment 1 is defined by a gas-tight substrate 11 and a gas-tight casing 12. The casing 12 is attached to the substrate 11 by means of a gas-tight seal, such as an adhesive, not illustrated in FIG. 1. According to embodiments, the gas-tight substrate 11 and the gas-tight casing 12 establish a container.

[0068] A gas generator 2 is arranged on the substrate 11 in the compartment 1, or elsewhere in the compartment 1. The gas generator 2 comprises a material 21 emitting the target gas in response to thermal activation. A heater 22 of the gas generator 2 provides for the thermal activation, and hence, is thermally coupled to the thermally activatable material 21. The gas generator 2 may include a housing as indicated in FIG. 1 supporting the material 21 and, possibly, the electrical heater 22.

[0069] It is preferred that the substrate 11 comprises electrically conducting paths (not shown). Accordingly, the electrical heater 22 of the gas generator is electrically connected to the substrate 11, and hence to electrically conducting paths on/in the substrate 11.

[0070] In addition, a reference sensor 3 is arranged on the substrate 11 in the compartment 1. The reference sensor 3 is configured to sense a concentration of a target gas, such as O.sub.2, in the compartment 1. The reference sensor 3 is likewise electrically connected to conducting paths of the substrate 11. Further, a control unit 4 is provided outside of the compartment 1. The control unit 4 is configured to control the gas generator 2 by means of a control signal to achieve and maintain a target gas concentration in the compartment 1 of a constant level, dependent on a sensor signal supplied from the reference sensor 3. Hence, corresponding electrical connections (not shown) are provided to the gas generator 2 and the reference sensor 3.

[0071] A unit 6 under test preferably is arranged in the compartment 1. The unit 6 desirably is exposed to the target gas at a preferably stable concentration over a desired time in order to evaluate an impact of the target gas on the unit 6 under test.

[0072] FIG. 2 illustrates a device according to an embodiment of the present invention. Same components are referred to by the same reference numerals as in FIG. 1. In this embodiment, the control unit 4 is arranged inside the compartment 1.

[0073] The reference sensor 3 and the gas generator 2 are both electrically connected to the control unit 4 by means of the conducting paths on/in the substrate 11.

[0074] Preferably, one or more electrical connections 51 are provided from the compartment 1 to the outside, i.e. the exterior. By such electrical connection, the control unit 4 may supply data to the outside, such as data on a necessity to have released target gas from the gas generator, or data about the stock of the material 22. Presently, the electrical connection reaches through the support 11. However, it may alternatively reach through the casing 12 or any other component defining the compartment 1. The electrical connection 51 is arranged in a gas-tight feedthrough 52 providing a sealing of in of the compartment 1 at the location of the electrical connection 51.

[0075] In an embodiment, where the control unit 4 is arranged outside the compartment 1, the electrical connections 51 in the feedthroughs 52 may serve to receive, at the control unit 4, the sensor signal from the reference sensor 3, and to send, from the control unit 4, the control signal to the gas generator 2.

[0076] FIG. 3 illustrates a feedback control loop as implemented in a device according to an embodiment of the present invention. In particular, the feedback control loop may be implemented by means of a reference sensor 3 as input means, a gas generator 1 as controlled system, and a control unit implementing the controlling function, such as e.g. described in connection with FIG. 1. The control unit 4 preferably is provided in form of an integrated circuit. However, the functionality of the control unit 4 may alternatively be embodied as analogue circuit.

[0077] The control loop includes a comparator 41, and a controller 42. The comparator 41 compares a sensor signal rs from the reference sensor 3 to a constant value cv, i.e. a target value for the concentration of the target gas in the compartment 1 which is set up-front. An output of the comparator 41 supplies a difference signal cv-rs between the constant value cv and the sensor signal rs representing the sensed actual target gas concentration to the controller 42, which in the present embodiment is a PI controller 42. The PI controller 42 translates the difference signal cv-rs into a control signal cs to control the gas generator 2, and in the present embodiment an electrical heater of the gas generator 2. The gas generator 2 in turn impacts a target gas concentration tg in the compartment.

[0078] FIG. 4 illustrates a flow chart illustrating a method for controlling a concentration of a target gas in a compartment according to an embodiment of the present invention, e.g. for the application of a unit under test. In step S0, the device is started for operation. In a first step S1, an actual concentration of the target gas inside the compartment is sensed by a reference sensor. In step S2, the sensed actual target gas concentration is compared to a constant value. In case the target gas concentration exceeds or is equal to the constant value (Y), it is returned to step S1 and the target gas concentration in the compartment is sensed in a next time step. In case the target gas concentration is below the constant value (N), a gas generator in the compartment is activated to release the target gas, thereby increasing the target gas concentration in the compartment. It is returned to step S1 and the target gas concentration in the compartment is sensed in a next time step.