Patent ID: 12209983

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG.1shows an example of a sensor10that is implemented as an ozone sensor. The sensor10is operable to measure ozone concentration. The sensor10comprises an ozone sensing component11, abbreviated as sensing component, and an ozone modifying component12, abbreviated as modifying component. The modifying component12is configured to destroy ozone. The modifying component12may be named device. The modifying component12is realized such that it destroys ozone via a physical effect such as temperature or ultraviolet radiation, abbreviated as UV. The modifying component12is configured as internal reference source.

Moreover, the sensor10comprises an outer housing13having an interior14. A first inlet15is integrated into the outer housing13. Gas can flow from the ambience or environment through the first inlet15into the interior14of the outer housing13. Gas can be named air or gaseous matter. Moreover, the sensor10comprises an inner housing16having an interior17. The sensing component11is arranged in the interior17of the inner housing16. The modifying component12is disposed within the interior14of the outer housing13or is partially disposed within the interior14of the outer housing13and partially disposed outside of the interior14of the outer housing13.

The first inlet15is configured to conduct gas from an outside of the outer housing13into the interior14of the outer housing13. The gas is able to diffuse or flow from the interior14of the outer housing13via the modifying component12to the interior17of the inner housing16and thus to the sensing component11. Thus, the gas is conducted from the interior14of the outer housing13into the interior16of the inner housing17and adjacent to the sensing component11.

The sensing component11generates a sensing component signal SI which corresponds to the ozone concentration of the gaseous matter within the interior17of the inner housing16. The sensing component11may also be named ozone component sensor. The sensing component signal SI can also be named ozone sensing component signal. The sensing component11may be realized as a UV sensing component or a metal oxide semiconductor sensing component. The sensing component signal SI typically has a base line and a span, wherein a base line and a span error may potentially be observed.

The modifying component12is operable to alter the ozone concentration of the gas within the interior14of the outer housing13or between the interior14of the outer housing13and the interior17of the inner housing16. The modifying component12is switched off in a first phase A and is switched on in a second phase B (as shown inFIG.4A). The first and the second phases A, B alternate. The switching on and off of the modifying component12leads to a destruction/recovery of the sensing component signal SI.

The sensing component11generates the sensing component signal SI as a raw signal SR in the first phase A and as a calibration signal SCA in the second phase B. The ozone concentration in the interior17of the inner housing16increases in the first phase A and decreases in the second phase B. This effect can be used as in application calibration signal. The calibration signal can be determined in an application that means during operation. Calibration can be performed, since the modifying component12produces a physical effect that is predictable. A steady state value of the ozone concentration in the first phase A mainly depends on the ozone concentration in the ambience or environment of the sensor10. A steady state value of the ozone concentration in the second phase B mainly depends on the modifying component12and may be e.g. zero.

In an alternative embodiment, not shown, the modifying component12is configured to generate ozone. Thus, the ozone concentration in the interior17of the inner housing16decreases in the first phase A and increases in the second phase B.

FIG.2shows an example of reactions between oxygen O2, ozone O3 and molecular oxygen O. An ozone decay can be explained via a Chapman mechanism. A schematic for the Chapman mechanism is shown inFIG.2. Rate constants for reactions (R1)-(R4) have been measured in the laboratory. Reactions (R2) and (R3) are found to be much faster than reactions (R1) and (R4). There is a rapid cycle between O and O3 by reactions (R2) and (R3), and a slower cycle between O2 and (O+O3) by (R1) and (R4). Because of the rapid cycling between O and O3 it is convenient to refer to the sum of the two as a chemical family, odd oxygen (Ox=O3+O), which is produced by (R1) and consumed by (R4). Simple relationships between O2, O, and O3 concentrations can be derived from a chemical steady-state analysis of the Chapman mechanism.

FIG.3Ashows an example of the sensor10which is a further development of the embodiment shown inFIG.1. On the left side ofFIG.3A, a cross-section is elucidated. On the right side ofFIG.3A, a view to the first inlet15of the outer housing13is shown. The inner housing16is located inside of the outer housing13. The inner housing16is arranged within the interior14of the outer housing13. The inner housing16comprises a second inlet21. The second inlet21is configured to conduct gas from the interior14of the outer housing13into the interior17of the inner housing16and adjacent to the sensing component11. The outer housing13can be realized as a lid or overall lid.

The sensor10comprises a substrate22. The sensing component11is arranged on the substrate22. The sensing component11may be arranged via a carrier23or layer to the substrate22. The carrier23or layer may provide a thermal isolation, for example.

The modifying component12is located on the substrate22. The modifying component12may be arranged to the substrate22via a body24of the sensor10or layer of the sensor10. The body24or layer may be designed for thermal isolation of the modifying component12to the substrate22.

The gas, which is also called air or gaseous matter, flows through the first inlet15into the interior14of the outer housing13. In the second phase B, the modifying component12has an influence on the ozone concentration in the interior14of the outer housing13. The modifying component12decreases the ozone concentration in the interior14of the outer housing13. The gas further flows from the interior14of the outer housing through the second inlet21into the interior17of the inner housing16and thus to the sensing component11. Depending on the dimensions and the time constant for diffusion, the ozone concentration decreases in the interior14of the outer housing13and then the ozone concentration in the interior17of the inner housing16also decreases.

The first phase A may follow the second phase B. In an embodiment, the sensor10is continuously operating. Thus, a first phase A is between two second phases B. A second phase B is between two first phases A.

In the first phase A, the modifying component12is switched off. Thus, the ozone concentration inside the interior14of the outer housing13and consequently also the ozone concentration in the interior17of the inner housing16and thus at the sensing component11rises to the value of the ozone concentration in the ambience or environment. The modifying component12has an effect on the gas, for example by the heat generated by the modifying component12. The modifying component12may comprise a heat source25. The heat source25may comprise a resistor. The heat source25may be fabricated as a micro-electro-mechanical system, shorted MEMS system. The heat source25may be implemented as a micro-heater or hot-plate. The modifying component12is configured to increase the temperature of the gaseous matter in the interior14of the outer housing13. The interior14of the outer housing13can also be named cavity. Therefore, the resistor is able to make the cavity hot. Thus, the modifying component12emits infrared radiation.

Advantageously, the inner housing16decouples the sensing component11from the modifying component12. The sensor10is configured such that the sensor10is free of a transfer of radiation from the modifying component12to the sensing component11.

The substrate may be realized as a printed circuit board, abbreviated as PCB, or a ceramic substrate, for example aluminum oxide ceramic or aluminum nitride ceramic. The outer housing13is inert with respect to ozone. Alternatively, the interior surface or inner side of the outer housing13is covered by a layer which is inert with respect to ozone. Thus, the interior surface of the outer housing13has no decreasing or increasing effect on the ozone concentration. For example, the outer housing13or a layer at the interior surface of the outer housing13is made from a material of a group consisting of an iron-nickel alloy, a noble metal, an epoxide and a polytetrafluoroethylene. For example, the outer housing13is realized by a polymer which is coated by a metal layer on the inner side.

Also the inner housing16is inert with respect to ozone. The inner housing16may be covered at both sides or made from a material of a group consisting of an iron-nickel alloy, a noble metal, an epoxide and a polytetrafluoroethylene.

As shown inFIG.3A, there is exactly one opening between the interior14of the outer housing13and the interior17of the inner housing16, namely the second inlet21. The number of openings between the interior14of the outer housing13and the interior17of the inner housing16is exactly one.

The outer housing13is attached to the substrate22. The outer housing13may be closed by the substrate22, wherein the first inlet15remains open. The substrate22may be named carrier. The attachment of the outer housing13to the substrate22may be gas-tight or nearly gas-tight. A surface of the substrate22is inert with respect to ozone.

The inner housing16is also attached to the substrate22. This attachment may be gas-tight or nearly gas-tight. As shown inFIG.3A, the inner housing16is connected to the carrier23that is connected to the substrate22. Thus, the inner housing16is fixed via the carrier23to the substrate22. Alternatively, the inner housing16may be directly fixed to the substrate22.

Advantageously, the inner housing16decouples the measuring of the ozone by the sensing component11from the destruction of ozone by the modifying component12.

Alternatively, the sensing component11may be directly attached to the substrate22, e.g. by a glue. The carrier23is omitted.

Alternatively, the modifying component12may be directly connected to the substrate22, e.g. by a glue.

In an alternative, not shown, embodiment, the second inlet21comprises more than one opening such as two, three, four and more than four openings.

FIG.3Bshows a further example of the sensor10which is a further development of the above embodiments. The modifying component12comprises a light source30. The light source30may be realized as a light-emitting diode, abbreviated as LED. The LED may be implemented as an ultraviolet radiation LED, abbreviated as UV LED. The modifying component12comprises a first number of light sources30. The first number may be 1, 2, 3, 4 or more than 4. The modifying component12has an effect on the gas, namely by the UV radiation emitted by the light source30. The interior housing16and especially the second inlet21in the interior housing16are located such that any radiation emitted by the light source30has only a small influence on the sensing component11. Advantageously, the modifying component12and the sensing component11are arranged between the outer housing13and the substrate22.

The sensor10may be free of any valve for control of gas-flow or air-flow. The sensor10may be free of any pump or fan for movement of gas. Since the sensor10is free of any mechanically active part or mechanical actuator, lifetime of the sensor10is increased and power consumption is decreased.

The gas inside the interior17of the inner housing16has only one path to the outside, namely via the second inlet21, the interior14of the outer housing13and the first inlet15. The sensor10is free of a further path for the gas that is in the interior17of the inner housing16to the ambience or environment.

The sensor10is not realized as a flow-through system. The sensor10is not implemented as a tube system in which gas is able to flow from a first opening of the tube via the modifying component12and the sensing component11to a second opening of the tube.

FIG.3Cshows a further example of the sensor10which is a further development of the above-shown embodiments. The outer housing13is attached to the substrate22. The outer housing13has a first side, not shown, connected to the substrate22and a second side which is opposite to the first side. The modifying component12is located at the second side. The modifying component12comprises at least one light source30. The light source30is realized as a light-emitting diode, abbreviated LED. In the example shown inFIG.3C, the number of light sources30to34is five. The sensor10comprises a driver35that is connected on its output side to the modifying component12. Thus, the driver35is coupled to the terminals of the at least one light source30. The sensor10may comprise a resistor36coupling the driver35to the at least one light source30. The at least one light source30may be realized as a UV LED. The at least one light source30emits light at a wavelength of about 278 nm.

Moreover, the sensor10comprises a processor41that is connected to the driver35. The processor41may be realized as a microprocessor or a microcontroller. The sensor10comprises a memory45coupled to the processor41.

The first inlet15is realized as a tube28. The sensing component11is coupled via the inner housing16to the outer housing13. The inner housing16may also comprise a tube29.

The sensor10may comprise a further substrate42on which the sensing component11is attached. A sensor driver43of the sensor10is arranged on the further substrate42. The sensor driver43is coupled to the sensing component11. The sensor driver43may be coupled to the processor41. The processor41comprises an interface44for providing a sensor output signal SOUT.

In an alternative, not shown embodiment, the sensing component11and the sensor driver43are arranged on the substrate22. Thus, the further substrate42can be omitted.

In an alternative, not shown embodiment, at least two circuits of the processor41, the sensor driver43, the memory45and the driver35are integrated on a semiconductor body.

FIG.3Dshows an example of details of the sensor10which is a further development of the above-shown embodiments. The sensing component11may comprise a hot-plate structure50which includes a heater. The sensing component11may be fabricated as a micro-electro-mechanical system, shorted MEMS system. The sensing component11may be realized as tungsten-oxide or tungsten-trioxide sensing component, shorted WO3 sensing component. The sensing component11may be operated in an isothermal manner. The sensing component11has a sensing layer51on the hot-plate structure50. The sensing layer51may e.g. comprise tungsten-trioxide.

The sensing component11may be on a transistor outline package52, shorted TO package. The TO package52comprises a header53and a cap54. The carrier23may be realized by the header53of the TO package52. The inner housing16may comprise the cap54of the TO package. The cap54has an opening55. The second inlet21may be realized by the opening55of the cap54and the tube29. The tube29is fixed to the cap54. The header53and the cap54are both metallic. Alternatively, the cap54is made out of a polymer. Electrodes56,57of the sensing component11are coupled via bonding wires58,59to pins60,61of the header53. The hot-plate structure50and thus the sensing component11are disposed in the interior17of the inner housing16.

FIG.3Eshows a further example of the sensor10which is a further development of the above-shown examples. The tube29is omitted. The first inlet15is realized as an opening in the outer housing13. Thus, advantageously, the distance of the ambience to the modifying component12is reduced. The inner housing16may be realized by the cap54of the TO package52. The cap54is directly attached to the outer housing12. The cap54is at least partially located inside the outer housing13. Thus, the inner housing16is disposed within an interior14of the outer housing13. The second inlet21is realized by the opening55or the openings of the cap54. Thus, the volume of the inner housing16is reduced. The distance of the sensing component11to the modifying component12is diminished. The sensing component11is arranged on the second side of the outer housing13. The further substrate42is attached to the second side of the outer housing13. Advantageously, the modifying component12and the sensing component11are accessible from the top of the sensor10. The modifying component12and the sensing component11are indirectly disposed on the substrate22.

The sensing component11operates at a constant temperature. The sensing component11performs an isothermal operation. The power provided to the sensing component11may be for example approximately 40 mW, resulting in a temperature of the sensing component11of 300° C.

In an alternative, not shown embodiment, the at least one light source30of the modifying component12is directly attached to the substrate22. Thus, the outer housing13may be turned by 180 degree with respect to an axis parallel to the substrate22.

In an alternative, not shown embodiment, the sensing component11or the carrier23with the sensing component11is directly attached to the substrate22. Thus, the further substrate42can be omitted. The carrier23may be implemented by the header53.

FIG.4Ashows an example of a signal of the sensor10according to one of the embodiments shown above. A control signal SC is shown as a function of a time t. The control signal SC controls the modifying component12. In the first phase A, the control signal SC has a first logical value (for example the value 0) and the modifying component12is switched off. In the second phase B, the control signal SC has a second logical value (for example the value 1) and thus the modifying component12is operating. In the first phase A, the at least one light source30does not emit light, whereas in the second phase B the at least one light source30emits light. The first phase A and the second phase B alternate. The first phase A and the second phase B are cyclically repeated. The first phase A has a first duration TA and the second phase B has a second duration TB. Alternatively, in the first phase A, the heat source25does not provide heat, whereas in the second phase B heat source25provides heat.

A cycle consists of one first phase A and one second phase B. A duration of one cycle is equal to TA+TB. The first duration TA may be, for example, between 0.5 seconds and 30 minutes. The second duration TB may be between 0.5 seconds and 60 minutes. Alternatively, the first duration TA may be between 0.5 seconds and 20 minutes and the second duration TB may be between 0.5 seconds and 30 minutes. Alternatively, the first duration TA may be between 0.5 seconds and 20 minutes and the second duration TB may be between 0.5 seconds and 30 minutes. In an example, the first duration TA lasts 10 minutes and the second duration TB lasts 20 minutes. These values are only example values.

FIG.4Bshows an example of a signal of the sensor10according to one of the embodiments shown above. The sensing component signal SI is shown as a function of a number N of ticks which may be the number of measurements. 10000 ticks may be equivalent to about 54 minutes. The sensing component signal SI is shown as a function of the time t. The sensing component signal SI may be e.g. a resistance value of a metal-oxide-semiconductor sensing layer51of the sensing component11. In the example shown inFIG.4B, the measurement starts with the second phase B. The sensing component signal SI decreases in the second phase B and increases in the first phase A. The sensing component signal SI in the second phase B is named calibration signal SCA and sensing component signal SI in the first phase A is named raw signal SR.

In a cycle, the lowest value of the sensing component signal SI can be achieved at the end of the second phase B and the largest value of the sensing component signal SI can be measured at the end of the first phase A. As shown inFIG.4B, several cycles are required such that the lowest values of the sensing component signal SI measured in consecutive cycles have approximately the same value and also the highest values of the sensing component signal SI measured in consecutive cycles have approximately the same value. Thus, the system stabilizes after turning on. The ozone concentration may be constant in the measurement shown inFIG.4B.

FIG.4Cshows the sensing component signal SI as a function of the number of ticks N. InFIG.4C, a longer time period in comparison toFIG.1Bis shown. Measurement is performed at different concentrations of ozone. In a first measurement phase M1an ozone concentration of approximately 0 ppb is supplied to the sensor. In a second measurement phase M2, an ozone concentration of 50 ppb is provided to the sensor10. In a third measurement phase M3, an ozone concentration of 100 ppb is applied to the sensor10. In a fourth measurement phase M4, an ozone concentration of 150 ppb is given to the sensor10. The measurement results can be interpreted as follows: During each of the second phases B, the modifying component12is on (that means active) and thus the ultraviolet light emitted by the at least one light source30is present. Thus, the sensing component signal SI which is the resistance of the metal oxide semiconductor resistor falls. Thus, it can be assumed as a hypothesis that in the second phase or phases B, the ozone destruction occurs in the outer housing13. If the fall of the resistance value stops, a zero ozone concentration is reached. This would result in a reset of a baseline. At low values of the ozone concentration, the baseline BL can be correct.

In the first phase A, the modifying component12is idle, thus there is no ultraviolet light emitted by the at least one light source30. Therefore, the sensing component signal SI increases. As a hypothesis it can be assumed that the ozone concentration is not destroyed in the first phase or phases A. Assuming a fixed destruction rate (or generation rate) that is proportional to, for example, the ultraviolet intensity, this procedure can be used to calibrate the sensor sensitivity (that means a span reset).

The sensor output signal SOUT may be a function of the difference between the largest and the lowest value of the sensing component signal SI in a cycle. Thus, the sensor output signal SOUT may be a function of the difference between the value of the sensing component signal SI at the end of the first phase A and the value of the sensing component signal SI at the end of the second phase B. Thus, the sensor output signal SOUT may be a function of the difference between the highest value of the raw signal SR and the lowest value of the calibration signal SCA.

Alternatively, the sensor output signal SOUT is a function of the differences of a first number N of cycles, such as an average of the differences of the first number N of cycles. N may be 1, 2, 3, 4 or more than 4.

In an alternative embodiment, not shown, the modifying component12is realized as an ozone source. Thus, the sensing component signal SI (being the raw signal SR) decreases in the first phase or phases A and the SI (being the calibration signal SCA) increases in the second phase or phases B.

FIG.4Dshows an example of signals of analyzers. The signals are shown as a function of the time t. A first and a second signal S1are determined by commercial ozone analyzers. The timing schedule of the ozone concentrations for generating these signals S1, S2correlate with the timing schedule used for the measurement shown inFIG.4C. Approximately, the following ozone concentrations are applied to the analyzers: 50 ppb, 0.0 ppb, 100 ppb, 0 ppb, 150 ppb, 0 ppb.

FIG.5Ashows an example of an apparatus70with a sensor10that is realized as shown above. The apparatus70is realized as a mobile device71. The sensor10is incorporated inside the mobile device71. A cover of the mobile device71has an opening72for entry of air to the sensor10. The mobile device71may be a device for mobile communication, a smart device, a smart speaker or a home automation device.

FIG.5Bshows an example of the apparatus70with a sensor10that is realized as shown above. The apparatus70is realized as an indoor air monitor. The apparatus70has a housing73holding the sensor10. The housing73comprises an opening74(optionally with a sieve) to allow penetration of the gas to be detected to the sensor10. The apparatus70may comprise e.g. a battery75connected to the sensor10for power supply. An indicator76may be connected to the sensor10. The indicator76is implemented e.g. as a buzzer and/or a light source that provides an alarm when the sensor10measures an ozone concentration above a predetermined threshold. The apparatus70may be fixed to a wall77.

Alternatively, the apparatus70is realized as an outdoor air monitor, an automotive air monitor and an industrial air or gas monitor and a device for control of an ozone disinfection apparatus. The apparatus70may be portable or fixed to a carrier such as the wall77, a ceiling, a machine etc.

Alternatively, the apparatus70may be connected to a mobile device such as a device for mobile communication, a smart device, a smart speaker or a home automation device by a cable or wireless. The apparatus70may provide the measurement result to the mobile device and/or receive the electric power from the mobile device.

FIG.5Cshows an example of the apparatus70with a sensor10that is realized as shown above. The apparatus70is realized as a wearable device78. The sensor10is incorporated inside the wearable device78. A housing or cover of the wearable device78has the opening72for entry of air to the sensor10. The wearable device78may be a watch, a smart ring or an electronic textile.

The embodiments shown in theFIGS.1to5Cas stated represent exemplary embodiments of the improved sensor, therefore they do not constitute a complete list of all embodiments according to the improved sensor. Actual sensor configurations may vary from the embodiments shown in terms of shape, size and materials, for example.