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| o2_sensor [2025/01/17 02:50] – kenson | o2_sensor [2025/01/30 20:43] (current) – kenson |
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| * {{ :ocr60.pdf | Whitepaper describing use of 9,10-Diphenylanthracene for oxygen detection}} | * {{ :ocr60.pdf | Whitepaper describing use of 9,10-Diphenylanthracene for oxygen detection}} |
| * The oxygen quenching is predicted by the Stern-Volmer equation, and changes in intensity or lifetime of the fluorescence can be monitored | * The oxygen quenching is predicted by the Stern-Volmer equation, and changes in intensity or lifetime of the fluorescence can be monitored |
| | * Ruthenium complex |
| | * [[https://www.cyanagen.com/products/rubp3-pf62-ruthenium-complexes/]] |
| | * [[https://www.cyanagen.com/cyanacontent/uploads/Products/RuBP3-PF62/Documents/SDS/EN-IS_RuBP3-PF62-F3R050X_rev01.pdf]] |
| | * [[https://www.ruixibiotech.com/pts/ru-bpy3-pf6-2]] CAS: 60804-74-2 $400/g |
| | * {{:rubp3-pf62_transient_absorption.png?direct&400|}} |
| | * [[https://www.eevblog.com/forum/projects/accurate-pulse-width-measurement/]] |
| | * [[https://www.ti.com/product/TDC7200]] |
| | * Datasheet: [[https://www.ti.com/lit/ds/symlink/tdc7200.pdf]] |
| | * [[https://github.com/Yveaux/TDC7200]] |
| | * {{ :quenching_of_the_fluorescence_of_tris_2_2_bipyridine_ruthenium.pdf |Quenching of the Fluorescence of Tris (2,2’-Bipyridine) Ruthenium(II), |
| | [Ru(bipy)3]2+, by a Dimeric Copper(II) Complex}} |
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| ==== 390nm LED ==== | ==== 390nm LED ==== |
| ==== 3. Considerations for a 450 nm LED ==== | ==== 3. Considerations for a 450 nm LED ==== |
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| 1. **Absorption Spectrum of Rubrene** | - **Absorption Spectrum of Rubrene** |
| - Rubrene has a primary absorption peak around ~495–530 nm. However, it still absorbs sufficiently at ~450 nm to fluoresce orange. You won’t be hitting its absolute peak absorption, but in practice, 450 nm can still excite rubrene decently. | * Rubrene absorbs sufficiently at ~450 nm to fluoresce orange. |
| - You may consider verifying the absorbance in your final PDMS film to ensure you’re not “under-absorbing.” | * Verifying the absorbance in your final PDMS film to ensure you’re not “under-absorbing.” |
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| 2. **Film Thickness** | - **Film Thickness** |
| - If the film is too thick or dye concentration is too high, inner regions might not be excited properly due to light attenuation. | * If the film is too thick or dye concentration is too high, inner regions might not be excited properly due to light attenuation. |
| - A thickness of **~0.1–1 mm** is typical for sensor films, but this depends on optical design and the LED intensity. | * A thickness of **~0.1–1 mm** is typical for sensor films, but this depends on optical design and the LED intensity. |
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| 3. **Sensor Calibration** | - **Sensor Calibration** |
| - Once cured, measure the fluorescence intensity (and/or lifetime) under different known oxygen concentrations to build a calibration curve using the Stern–Volmer relationship. | * Once cured, measure the fluorescence intensity (and/or lifetime) under different known oxygen concentrations to build a calibration curve using the Stern–Volmer relationship. |
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| ## 4. Adjusting the Ratio Over Time | ==== 4. Adjusting the Ratio Over Time ==== |
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| - **If the Film Is Too Dark (Self-Absorbing)** | * **If the Film Is Too Dark (Self-Absorbing)** |
| - Lower the dye percentage. Even going from 0.1 wt% down to 0.02 wt% can make a big difference in clarity and reduce self-quenching. | * Lower the dye percentage. Even going from 0.1 wt% down to 0.02 wt% can make a big difference in clarity and reduce self-quenching. |
| - **If the Signal Is Too Dim** | * **If the Signal Is Too Dim** |
| - Increase the dye content in small increments (e.g., from 0.02 wt% up to 0.05 wt%), but watch for diminishing returns due to concentration quenching. | * Increase the dye content in small increments (e.g., from 0.02 wt% up to 0.05 wt%), but watch for diminishing returns due to concentration quenching. |
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| --- | ==== Bottom Line ==== |
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| ### Bottom Line | |
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| A good **starting point** is **0.01–0.1 wt% rubrene** relative to the PDMS base. Begin on the lower side (e.g., **0.02–0.05 wt%**) to avoid aggregation, see how bright the sensor is at 450 nm excitation, and adjust accordingly. Once you have a homogeneously dispersed rubrene-PDMS film, you can calibrate its oxygen response using the Stern–Volmer equation and fine-tune the formulation to optimize fluorescence intensity versus oxygen quenching sensitivity. | A good **starting point** is **0.01–0.1 wt% rubrene** relative to the PDMS base. Begin on the lower side (e.g., **0.02–0.05 wt%**) to avoid aggregation, see how bright the sensor is at 450 nm excitation, and adjust accordingly. Once you have a homogeneously dispersed rubrene-PDMS film, you can calibrate its oxygen response using the Stern–Volmer equation and fine-tune the formulation to optimize fluorescence intensity versus oxygen quenching sensitivity. |
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| ==== pH ==== | ==== pH optode sensor notes ==== |
| * {{ :nandi-amdursky-2022-the-dual-use-of-the-pyranine-_hpts_-fluorescent-probe-a-ground-state-ph-indicator-and-an-excited_1_.pdf | Pyranine (HPTS) Fluorescent Probe}} | * {{ :nandi-amdursky-2022-the-dual-use-of-the-pyranine-_hpts_-fluorescent-probe-a-ground-state-ph-indicator-and-an-excited_1_.pdf | Pyranine (HPTS) Fluorescent Probe}} |
| * Pyranine Solvent Green 7 CAS 6358-69-6 aka HPTS aka Pyranine | * Pyranine Solvent Green 7 CAS 6358-69-6 aka HPTS aka Pyranine |
