Sensor with holographic multiplexed image display

1. A holographic sensor, comprising: a thin film polymer matrix that undergoes a change in response to a substance to be sensed, the matrix comprising within its volume a set of two or more holographic recordings, each recording providing a holographic image when the sensor is illuminated, wherein the presence or appearance of each image is visible to a viewer's eye as a function of the response of the sensor to the substance to be sensed, and the images provide a dynamic range of the sensor, and wherein the sensor provides, in the absence of the substance, a first holographic image that is visible and a second holographic image that is invisible, and wherein, as a consequence of a wavelength shift in the presence of the substance, the first holographic image is invisible and the second holographic image is visible.

2. A sensor according to claim 1 , wherein each image has a unique location in the visible or invisible spectrum.

3. A sensor according to claim 1 , wherein each image is pictorial, numerical and/or alphabetical.

4. A sensor according to claim 1 , wherein the first visible holographic image is representative of the substance or a scenario in which the substance is found or the sensor is used.

5. A sensor according to claim 1 , wherein at least one of the first and second visible holographic images is numerical.

6. A sensor according to claim 1 , wherein the first visible holographic image is alphabetical and provides a message corresponding to the substance or a scenario in which substance is found or the sensor is used.

7. A sensor according to claim 1 , wherein the first visible holographic image has a location, in the space of the image, corresponding to or representative of the substance or a scenario in which the substance is found or the sensor is used.

8. A sensor according to claim 1 , wherein the first visible holographic image is calibrated with respect to the quantity of the substance.

9. A sensor according to claim 1 , which additionally comprises a visible scale.

10. A sensor according to claim 9 , wherein the scale is invariant with respect to the concentration of the substance.

11. A sensor according to claim 1 , which provides multiple images within one film.

12. A sensor according to claim 1 , which provides at least three images.

13. A sensor according to claim 1 , which comprises a plurality of films each providing its own dynamic range within the dynamic range of the sensor.

14. A sensor according to claim 1 , which comprises a plurality of films each responding to a different substance.

15. A sensor according to claim 1 , which additionally comprises colour transmission filter.

16. A sensor according to claim 1 , where the first visible holographic image is formed from a set of visible pixels, the pattern of pixels being indicative or representative of the substance or a scenario in which the substance is found or the sensor is used.

17. Apparatus comprising a sensor according to claim 1 and an illumination source.

18. A sensor comprising: a matrix that undergoes changes in response to a substance to be sensed, the matrix comprising within its volume multiplexed holographic images including a first holographic image having a first peak wavelength and a second holographic image different from the first holographic image having a second peak wavelength different from the first peak wavelength,

wherein, in the presence of the substance during a sensing operation, the first peak wavelength, but not the second peak wavelength, is in a visible range, whereby the first holographic image, but not the second holographic image is visible, and

wherein, in the absence of the substance during the sensing operation, the second peak wavelength, but not the first peak wavelength, is in a visible range and the second holographic image, but not the first holographic image, is visible.

19. A sensor according to claim 18 , wherein the multiplexed holographic images are embodied in a single polymer film.

20. A sensor according to claim 18 , wherein the multiplexed holographic images are embodied in multiple polymer films.

21. A sensor according to claim 18 , wherein the multiplexed holographic images comprise a third holographic image different from the first and second holographic images, the third holographic image having a peak wavelength in the visible range regardless of the presence or absence of the substance during the sensing operation.

22. A sensor according to claim 21 , wherein the third holographic image comprises a scale.

23. A sensor according to claim 18 , wherein the first image and the second image differ in one or more of pictorial, numerical and alphabetical features.

24. A method for making a holographic sensor containing a first recorded holographic image and a second recorded holographic image that are multiplexed in a matrix, the method comprising:

providing a matrix that has a plurality of states that are affected by a substance to be sensed;

recording within the volume of the matrix a first holographic image when the matrix is in a first state, the first holographic image having a first peak wavelength;

recording within the volume of the matrix a second holographic image when the matrix is in a second state that is different from the first state, the second holographic image having a second peak wavelength different from the first peak wavelength;

wherein when the matrix is in the first state, the first peak wavelength, but not the second peak wavelength, is in the visible range, whereby the first recorded holographic image, but not the second recorded holographic image is visible; and when the matrix is in the second state, the second peak wavelength, but not the first peak wavelength, is in the visible range and the second recorded holographic image recorded, but not the first recorded holographic image is visible.

25. The method of claim 24 , wherein the first state and the second state are different states of swelling.

26. The method of claim 25 , wherein the state of swelling is controlled by pH, ion concentration, humidity or water activity.

27. The method of claim 24 , wherein the first state and the second state are different states of thickness of the matrix.

28. The method of claim 24 , further comprising recording within the volume of the matrix a third holographic image when the matrix is in a third state.

29. A method for detecting a substance in a sample comprising:

sensing a sample, the sensing being done by a sensor exposed to the sample, the sensor comprising a matrix that undergoes changes in response to a substance to be sensed, the matrix comprising within its volume multiplexed holographic images including a first holographic image having a first peak wavelength and a second holographic image different from the first holographic image having a second peak wavelength different from the first peak wavelength,

wherein, in the presence of the substance during a sensing operation, the first peak wavelength, but not the second peak wavelength, is in a visible range, whereby the first holographic image, but not the second holographic image is visible, and

wherein, in the absence of the substance during the sensing operation, the second peak wavelength, but not the first peak wavelength, is in a visible range and the second holographic image, but not the first holographic image, is visible; and

replaying the holographic image by the sensor, wherein replay of the first holographic image, but not the second holographic image, is indicative of the presence of the substance in the sample.

30. A method for detecting a substance in a sample comprising:

sensing a sample, the sensing being done by a sensor exposed to the sample, the sensor comprises a thin film polymer matrix that undergoes a change in response to a substance to be sensed, the matrix comprising within its volume a set of two or more holographic recordings, each recording providing a holographic image when the sensor is illuminated, wherein the presence or appearance of each image is visible to a viewer's eye as a function of the response of the sensor to the substance to be sensed, and the images provide a dynamic range of the sensor, and wherein the sensor provides, in the absence of the substance, a first holographic image that is visible and a second holographic image that is invisible, and wherein, as a consequence of a wavelength shift in the presence of the substance, the first holographic image is invisible and the second holographic image is visible; and

replaying the holographic image by the sensor when the sensor is illuminated, wherein replay of the second holographic image, but not the first holographic image, is indicative of the presence of the substance in the sample.