US-12625080-B2 - Multi-color pulse-amplitude modulated handheld fluorescence imager

Abstract

A portable device operable to identify photosynthetic activity and contents of compounds in a plant part. The portable device includes a light source including light-emitting diodes operable to irradiate the plant part with light. The portable device further includes a control module operable to have the light-emitting diodes emit the light as pulse signals. Additionally, the portable device includes a focus-adjustable lens and a filter optically coupled to the light source, where the adjustable lens and the filter are co-operable to consolidate light reflected from the plant part which may be irradiated by light from the light-emitting diodes. Furthermore, the portable device includes a detector optically positioned to receive from the focus-adjustable lens and the filter the light reflected from the plant part, where the light reflected from the plant part corresponds to the photosynthetic activity and contents of compounds in the plant part.

Inventors

• Ruochong Zhang
• Dinish Unnimadhava Kurup Soudamini Amma
• Malini Carolene Devapiriyai Olivo
• Ju Teng Teo

Assignees

• AGENCY FOR SCIENCE, TECHNOLOGY AND RESEARCH

Dates

Publication Date

20260512

Application Date

20220914

Priority Date

20211011

Claims (17)

1. 1 . A portable device operable to identify photosynthetic activity and contents of compounds in a plant part, the portable device comprises: a light source comprising light-emitting diodes operable to irradiate the plant part with light comprising more than one wavelength; a control module operable to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals, which involve: the control module operable to have the light-emitting diodes irradiate red light on the plant part to induce a first far-red fluorescence intensity signal from the plant part, and then irradiate ultraviolet light on the plant part to induce a second far-red fluorescence intensity signal from the plant part; a focus-adjustable lens and a filter optically coupled to the light source, wherein the adjustable lens and the filter are co-operable to consolidate light reflected from the plant part which is irradiated by light from the light-emitting diodes; and a detector optically positioned to receive from the focus-adjustable lens and the filter the light reflected from the plant part, wherein the light reflected from the plant part corresponds to the photosynthetic activity and contents of compounds in the plant part, and the light reflected is transmitted as fluorescence, wherein, from the control module, a numerical value is rendered by dividing the first far-red fluorescence intensity signal by the second far-red fluorescence intensity signal; and having a flavonol content in the plant part identified by taking a logarithm of the numerical value.
2. 2 . The portable device of claim 1 , wherein the light source comprises the light-emitting diodes arranged circumferentially to the detector.
3. 3 . The portable device of claim 1 , wherein the light source comprises the light-emitting diodes arranged circumferentially on a panel, and wherein the panel comprises an opening which the detector is optically positioned at to receive the light reflected from the plant part.
4. 4 . The portable device of claim 1 , wherein the light comprising more than one wavelength has a wavelength ranging from 100 nm to 760 nm.
5. 5 . The portable device of claim 1 , wherein the control module is operable to have each of the light-emitting diodes independently emit light at different brightness.
6. 6 . The portable device of claim 1 , wherein the control module is operable to have the light-emitting diodes emit blue light, wherein the blue light comprises a first pulse signal and a second pulse signal, and wherein the first pulse signal has a shorter pulse width and a lower amplitude than the second pulse signal.
7. 7 . The portable device of claim 1 , wherein the control module is operable to have the light-emitting diodes emit red light and then green light, and wherein the red light and the green light are configured to produce identical photoactive radiation.
8. 8 . The portable device of claim 1 , wherein the red light and the ultraviolet light are configured to produce identical photoactive radiation.
9. 9 . The portable device of claim 1 , wherein the filter comprises a long-pass filter which consolidates fluorescence reflected from the plant part.
10. 10 . The portable device of claim 1 , wherein the detector is a charge-coupled device detector.
11. 11 . A method of identifying photosynthetic activity and contents of compounds in a plant part using the portable device of claim 1 , the method comprising: irradiating the plant part with light comprising more than one wavelength from a light source comprising light-emitting diodes; operating a control module to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals; operating a focus-adjustable lens and a filter to consolidate light reflected from the plant part which is irradiated by light from the light-emitting diodes, wherein the focus-adjustable lens and the filter are optically coupled to the light source; and operating a detector which is optically positioned to receive from the focus-adjustable lens and the filter the light reflected from the plant part, wherein the light reflected from the plant part corresponds to the photosynthetic activity and contents of compounds in the plant part, and the light reflected is transmitted as fluorescence, wherein operating a control module to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals comprises: operating the control module to have the light-emitting diodes irradiate red light on the plant part to induce a first far-red fluorescence intensity signal from the plant part, and then irradiate ultraviolet light on the plant part to induce a second far-red fluorescence intensity signal from the plant part, and further comprising: dividing the first far-red fluorescence intensity signal by the second far-red fluorescence intensity signal to obtain a numerical value; and taking a logarithm of the numerical value to identify a flavonol content in the plant part.
12. 12 . The method of claim 11 , wherein irradiating the plant part with the light comprising more than one wavelength comprises: operating the light-emitting diodes at a voltage ranging from 0.1 mV to 10 V; and/or operating each of the light-emitting diodes independently at 0.1 mA to 10 A to emit light at different brightness.
13. 13 . The method of claim 11 , wherein operating a control module to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals comprises: operating the control module to have the light-emitting diodes irradiate blue light having a first pulse signal on the plant part to induce a minimum or steady state fluorescence intensity signal from the plant part; operating the control module to have the light-emitting diodes irradiate blue light having a second pulse signal on the plant part to induce a maximum fluorescence intensity signal from the plant part in a lit environment; and wherein the first pulse signal has a shorter pulse width and a lower amplitude than the second pulse signal.
14. 14 . The method of claim 13 , wherein operating the control module to have the light-emitting diodes irradiate blue light having the first pulse signal on the plant part is carried out in a dark environment or a lit environment.
15. 15 . The method of claim 13 , further comprising: subtracting the maximum fluorescence intensity signal with the minimum or steady state fluorescence intensity signal to obtain a numerator; and dividing the numerator with the maximum fluorescence intensity signal to identify the photosynthetic activity.
16. 16 . The method of claim 11 , wherein operating a control module to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals comprises: operating the control module to have the light-emitting diodes irradiate red light on the plant part to induce a first far-red fluorescence intensity signal from the plant part, and then irradiate green light on the plant part to induce a second far-red fluorescence intensity signal from the plant part.
17. 17 . The method of claim 16 , further comprising: dividing the first far-red fluorescence intensity signal by the second far-red fluorescence intensity signal to obtain a numerical value; and taking a logarithm of the numerical value to identify anthocyanin content in the plant part.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of priority of Singapore Patent Application No. 10202111286W, filed 11 Oct. 2021, the content of it being hereby incorporated by reference in its entirety for all purposes. TECHNICAL FIELD The present disclosure relates to a portable device operable to identify photosynthetic activity and contents of compounds in a plant part. The present disclosure also relates to a method of identifying photosynthetic activity and contents of compounds in a plant part using the portable device. BACKGROUND Traditional lab based chemical and analytical methods for plant phenotyping may be accurate but unfortunately tend to be time-consuming. Chlorophyll fluorescence may be a key indicator of photosynthetic (PS) energy conversion in plants, which may be valuable as an alternative to be studied for replacing the traditional laboratory methods. Current fluorescence system for plant phenotyping tends to be either single-point measurement without imaging capability or imaging tends to be carried out relative to photosynthetic activity only. There appears to be no fluorescence imaging system operable to identify both photosynthetic activity and compound(s) that may be present in a plant, wherein the measurements can be taken pixel-wisely. There is thus a need to provide for a solution that addresses one or more of the limitations mentioned above. SUMMARY In a first aspect, there is provided for a portable device operable to identify photosynthetic activity and contents of compounds in a plant part, the portable device comprises: a light source comprising light-emitting diodes operable to irradiate the plant part with light comprising more than one wavelength;a control module operable to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals;a focus-adjustable lens and a filter optically coupled to the light source, wherein the adjustable lens and the filter are co-operable to consolidate light reflected from the plant part which is irradiated by light from the light-emitting diodes; anda detector optically positioned to receive from the focus-adjustable lens and the filter the light reflected from the plant part, wherein the light reflected from the plant part corresponds to the photosynthetic activity and contents of compounds in the plant part, and the light reflected is transmitted as fluorescence. In another aspect, there is provided a method of identifying photosynthetic activity and contents of compounds in a plant part using the portable device described in various embodiments of the first aspect, the method comprising: irradiating the plant part with light comprising more than one wavelength from a light source comprising light-emitting diodes;operating a control module to (i) have the light-emitting diodes emit the light as pulse signals and (ii) modulate amplitude and width of the pulse signals;operating a focus-adjustable lens and a filter to consolidate light reflected from the plant part which is irradiated by light from the light-emitting diodes, wherein the focus-adjustable lens and the filter are optically coupled to the light source; andoperating a detector which is optically positioned to receive from the focus-adjustable lens and the filter the light reflected from the plant part, wherein the light reflected from the plant part corresponds to the photosynthetic activity and contents of compounds in the plant part, and the light reflected is transmitted as fluorescence. BRIEF DESCRIPTION OF THE DRAWINGS The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the present disclosure. In the following description, various embodiments of the present disclosure are described with reference to the following drawings, in which: FIG. 1A is a photograph showing a device of the present disclosure (from a bottom-up view). The device is operable as a handheld multi-color pulse-amplitude modulated (PAM) fluorescence imager. As can be seen in FIG. 1A, the device includes a panel comprising various light-emitting diodes (LEDs) configured circumferentially thereon with a long pass filter (LPF) arranged in the center of the panel. The panel having the various LEDs may be collectively referred to herein as a light source. The various LEDs may include RGB (red-green-blue) LEDs and ultraviolet (UV) LEDs. In this non-limiting example prototype, there is a total of eight RGB LEDs arranged circumferential to the long pass filter. In addition, four UV LEDs are arranged peripheral to the RGB LEDs and circumferential to the long pass filter. FIG. 1B is a photograph showing a side view of the same device in FIG. 1A. FIG. 1B shows the charged coupled device (CCD) camera and lenses (e.g. wide-angle lenses), a side view of the long pass filter, and a side view of the panel comprising the various LEDs. The panel is a ring-shaped panel ha