Understanding pH Sensor Drift
When a pH sensor is first submerged, its potential can shift significantly in the first few hours before stabilizing. This is normal—whether you’re using microelectrodes (like ZP’s strips), glass probes, or stainless steel electrodes.
Key Observations from Our Data:
-
Early Drift: The biggest changes happen shortly after immersion.
-
Long-Term Stability: After several hours, the signal becomes much more consistent.
-
Impact on Accuracy: If you rely on a single-point calibration, this drift can lead to errors (e.g., pH 7.0 reading shifting to 7.8).
Solution? Smart Calibration Strategies
Instead of frequent recalibration, we recommend:
-
Pre-Submerging the Sensor – Let it stabilize in solution before taking measurements.
-
Two-Point Calibration After Stabilization – This corrects for initial drift without needing constant adjustments.
Why does this work?
-
The first exposure to liquid causes the most change.
-
After stabilization, subsequent uses show much faster settling times.
2. Bioreactor Monitoring: Do You Need Frequent Recalibration?
A common question: *”If I’m running a bioreactor for 16+ hours, do I need to recalibrate the sensor multiple times?”*
Short answer: No.
Our Recommended Approach:
-
Pre-Submerge the Sensor (e.g., in a buffer or similar solution).
-
Perform a Two-Point Calibration (after stabilization).
-
Deploy in the Bioreactor.
Result?
-
The sensor remains stable for the entire run.
-
No need for mid-experiment recalibration.
This method has worked reliably in our tests, ensuring long-term accuracy without extra hassle.
3. Can ZP Make Longer Sensor Strips?
Many users ask if we can produce extended-length pH sensors for deeper immersion (e.g., in large bioreactors).
Technically? Yes. Practically? It’s complicated.
Challenges with Custom Lengths:
✅ Possible? – Yes, we could manufacture longer strips.
❌ But…
-
Higher Costs – Longer strips mean fewer sensors per batch, increasing unit price.
-
Retooling Required – Our production is optimized for current dimensions.
-
Quality Control Adjustments – Longer strips may need new testing protocols.
Our Advice: Work with Standard Sensors First
Before pursuing customization:
-
Test the existing sensor in your setup.
-
Explore alternative mounting solutions (e.g., adapters, extended cables).
Why?
-
Proven Reliability – Our standard sensors are well-tested and mass-produced.
-
Cost-Effective – Customization adds R&D expenses, which get passed on.
If you still need a longer sensor after testing, we can discuss—but expect higher costs and lead times.
Final Thoughts
ZP micro pH sensors are designed for stability and ease of use. By:
✔ Pre-submerging before calibration
✔ Using two-point calibration post-stabilization
✔ Sticking with standard lengths where possible
…you’ll get accurate, long-term pH monitoring without unnecessary recalibration or customization costs.
Have more questions? Drop them in the comments or reach out—we’re happy to help!
