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o2_sensor [2025/01/17 02:43] – kensono2_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}}
  
 ==== 390nm LED ==== ==== 390nm LED ====
Line 49: Line 60:
 {{:photodiodespectra.png?direct&600|}} {{:photodiodespectra.png?direct&600|}}
  
-==== Making sample ====+===== Making Rubene Samples ===== 
 + 
 +==== Doping rubrene into PDMS ====  
 +(e.g., Sylgard 184 or a similar PDMS variant like Sylcap 284).
  
-Doping rubrene into PDMS (e.g., Sylgard 184 or a similar PDMS variant like Sylcap 284) 
 Most published oxygen-sensor designs with rubrene start in a relatively narrow doping range to balance brightness and avoid dye aggregation or self-quenching. Most published oxygen-sensor designs with rubrene start in a relatively narrow doping range to balance brightness and avoid dye aggregation or self-quenching.
  
-## 1. Typical Doping Range ## +==== 1. Typical Doping Range ====
   * **Starting Point**: **0.01–0.1 wt%** (by weight of rubrene relative to the total weight of uncured PDMS) is a commonly cited window.     * **Starting Point**: **0.01–0.1 wt%** (by weight of rubrene relative to the total weight of uncured PDMS) is a commonly cited window.  
   * In practical terms, this might translate to about **0.1–1 mg of rubrene per gram of PDMS base**.     * In practical terms, this might translate to about **0.1–1 mg of rubrene per gram of PDMS base**.  
   * If you see **aggregation** or **self-quenching** (the fluorescence drops because the molecules are packed too closely), reduce the concentration. If the **signal is too weak**, you can increase it slightly toward the upper end of the range.   * If you see **aggregation** or **self-quenching** (the fluorescence drops because the molecules are packed too closely), reduce the concentration. If the **signal is too weak**, you can increase it slightly toward the upper end of the range.
  
-### Why This Range? ###+=== Why This Range? ===
  
-  - **Fluorescence Brightness vs. Self-Quenching**  +  - **Fluorescence Brightness vs. Self-Quenching**
     * Rubrene is highly fluorescent, so even a small concentration can yield significant emission.       * Rubrene is highly fluorescent, so even a small concentration can yield significant emission.  
     * Above roughly **0.1–0.2 wt%**, many organic dyes (including rubrene) begin to exhibit “concentration quenching,” where the emission drops due to exciton–exciton annihilation or dye aggregation.     * Above roughly **0.1–0.2 wt%**, many organic dyes (including rubrene) begin to exhibit “concentration quenching,” where the emission drops due to exciton–exciton annihilation or dye aggregation.
  
   - **Cost and Solubility**     - **Cost and Solubility**  
-   - Rubrene can be expensive, and it’s only moderately soluble in typical organic solvents. Over-saturating the mix will result in precipitates, optical scattering, or inhomogeneous films. +    * Rubrene can be expensive, and it’s only moderately soluble in typical organic solvents. Over-saturating the mix will result in precipitates, optical scattering, or inhomogeneous films.
- +
-3. **Oxygen Diffusion**   +
-   - PDMS is highly oxygen-permeable, which is great for oxygen sensing but also means the dye gets quenched quickly. Going too high in dye content doesn’t necessarily improve sensitivity—it may just cause more self-quenching without improving the sensor’s performance. +
- +
---- +
- +
-## 2. Practical Mixing Tips+
  
-1. **Pre-Dissolve the Rubrene**   +  - **Oxygen Diffusion**   
-   - Dissolve rubrene in a small volume of an organic solvent (toluene or chloroform) at a known concentration (e.g., 1–10 mg/mL).   +    * PDMS is highly oxygen-permeable, which is great for oxygen sensing but also means the dye gets quenched quickly. Going too high in dye content doesn’t necessarily improve sensitivity—it may just cause more self-quenching without improving the sensor’s performance.
-   - Slowly add this solution to the PDMS base resin while stirring. This helps achieve more uniform dispersal.+
  
-2. **Degas**   +==== 2. Practical Mixing Tips ====
-   - After mixing, place the solution under vacuum to remove both solvent and air bubbles.   +
-   - If you have a two-part system (base + curing agent), you might do a preliminary degassing before adding the curing agent, then a final degassing after thoroughly mixing in the catalyst.+
  
-3. **Curing**   +  - **Pre-Dissolve the Rubrene**   
-   - Many PDMS systems can cure at room temperature in 24–48 hours or at 60–70 °C for a few hours.   +    * Dissolve rubrene in a small volume of an organic solvent (toluene or chloroform) at a known concentration (e.g., 1–10 mg/mL).   
-   - Try not to exceed 120 °C or keep the mixture at high temperature for too long—rubrene will degrade over time if both heat and oxygen are present.+    * Slowly add this solution to the PDMS base resin while stirring. This helps achieve more uniform dispersal.
  
----+  - **Degas**   
 +    * After mixing, place the solution under vacuum to remove both solvent and air bubbles.   
 +    * If you have a two-part system (base + curing agent), you might do a preliminary degassing before adding the curing agent, then a final degassing after thoroughly mixing in the catalyst.
  
-## 3. Considerations for a 450 nm LED+  - **Curing**   
 +    * Many PDMS systems can cure at room temperature in 24–48 hours or at 60–70 °C for a few hours.   
 +    * Try not to exceed 120 °C or keep the mixture at high temperature for too long—rubrene will degrade over time if both heat and oxygen are present.
  
-1. **Absorption Spectrum of Rubrene**   +==== 3. Considerations for a 450 nm LED ====
-   - 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.   +
-   - You may consider verifying the absorbance in your final PDMS film to ensure you’re not “under-absorbing.”+
  
-2. **Film Thickness**   +  - **Absorption Spectrum of Rubrene**   
-   - If the film is too thick or dye concentration is too high, inner regions might not be excited properly due to light attenuation.   +    * Rubrene absorbs sufficiently at ~450 nm to fluoresce orange.  
-   - A thickness of **~0.1–1 mm** is typical for sensor films, but this depends on optical design and the LED intensity.+    * Verifying the absorbance in your final PDMS film to ensure you’re not “under-absorbing.”
  
-3. **Sensor Calibration**   +  - **Film Thickness**   
-   - Once cured, measure the fluorescence intensity (and/or lifetime) under different known oxygen concentrations to build a calibration curve using the Stern–Volmer relationship.+    * 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.
  
----+  - **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.
  
-## 4. Adjusting the Ratio Over Time 
  
-- **If the Film Is Too Dark (Self-Absorbing)**   +==== 4. Adjusting the Ratio Over Time ====
-  - 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**   +
-  - 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.+
  
----+  * **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.   
 +  * **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.
  
-### Bottom Line+==== Bottom Line ====
  
 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.
  
-==== 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
o2_sensor.1737081828.txt.gz · Last modified: 2025/01/17 02:43 by kenson
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