AbhilekhVaccine cold chain · 2–8 °CVaccine and pharmacy refrigerator temperature monitoring
A vaccine fridge fails quietly. The door seal ages, the defrost cycle overshoots, someone puts a warm carton on the top shelf — and the only evidence that the batch is still good is the record you kept while nobody was watching.
The 2–8 °C band is the narrowest routine cold chain in healthcare and the least forgiving. A domestic-style refrigerator cycles by several degrees between compressor runs, the top shelf and the vegetable drawer are not the same temperature, and a defrost cycle can push the coldest point below zero — which for most vaccines is a hard excursion, not a soft one.
Getting this right needs three things that a pen-and-clipboard log cannot deliver: accuracy at the point that matters, continuity through nights and weekends, and an alert that reaches a human before the excursion becomes a write-off. The measurement must also be made where the product is, which is why glycol-buffered or probe-in-product measurement is the convention rather than sensing free air.
Abhilekh's fridge units keep the electronics outside and the sensing element inside — through the door seal on a thin cabled probe, or on a Class-A PT100 immersion probe in a buffer — so the record reflects product temperature rather than how often the door opened.
The expectations behind the record
What an inspector or auditor looks for in this use case, and the framework each expectation comes from.
Continuous monitoring with an alarm, not a twice-daily reading
Health cold-chain performance specifications expect a device that logs continuously, retains a usable history, and raises a local alarm on an excursion — so a failure that starts on Friday evening is not discovered on Monday morning.
Accuracy demonstrated at the working temperature
A ±0.5 °C sensor calibrated at 25 °C tells you less than you think at 4 °C. The calibration points must bracket the band you operate in, with a traceable certificate on file and a defined recalibration interval.
Records an inspector can read without your help
Electronic records must be retrievable in human-readable form for the retention period, with a secure time-stamped audit trail of any change and e-signatures that carry identity, timestamp and meaning of signature.
A documented response when the band is breached
The alert is the beginning of the obligation, not the end. Acknowledgement, assessment against product stability data, quarantine and CAPA all need to attach to the excursion record so the decision is auditable later.
The failure modes nobody budgets for
Every one of these is a real reason monitoring programmes lose their audit trail — or lose the trust of the people who work with them.
Air temperature is not product temperature
Free-air sensing follows every door opening and makes the fridge look far less stable than the vials inside it. Unbuffered alarms then get disabled by staff who are tired of false pages.
Defrost overshoot below zero
Freeze damage is invisible and, for adjuvanted vaccines, irreversible. A logger that samples every 30 minutes can miss a short sub-zero dip entirely.
Nobody sees the display
A monitor that shows the reading only on a website is useless to the pharmacist standing at the door, and a monitor that shows it only on the unit is useless to the QA lead at head office.
Manual logs that are completed from memory
Twice-daily paper rounds cover roughly 2 % of the week and are routinely back-filled. They are also the first thing an auditor tests for contemporaneity.
Engineered for this, specifically
Each point below maps to a documented platform behaviour — not a marketing promise.
Probe through the seal, electronics outside
ABH-200-E puts a 1.5 m cabled SHT45 T+RH head inside the cabinet and keeps the monitor, display and radio outside — no drilling, no cabinet modification. ABH-200 pairs with a Class-A PT100 immersion probe where you want ±0.15 °C at 0 °C in a glycol buffer.
The reading is visible on the door and in the cloud
A 1.54″ e-paper display holds the last reading even when the unit sleeps, and the status LED is unambiguous: green in specification, blinking red on excursion, solid red when the instrument itself needs attention. The same reading is live in the web and mobile apps.
Sample fast enough to catch a defrost dip
Sampling goes down to one second, with 60 s and 300 s firmware defaults. An alarm edge opens an upload window immediately rather than waiting for the next scheduled window.
The excursion becomes a workflow, not a notification
Operators acknowledge and annotate from the mobile app at the fridge door — biometric login, device QR pairing — and the acknowledgement, assessment and CAPA attach to the excursion inside the same audit trail.
Calibration tracked per probe, not per site
Probe channel templates live in the logger's ID EEPROM, and the platform tracks NIST-traceable certificates, due dates and reminders for each probe individually. Reports carry the calibration status of every device in scope.
The ABH loggers for this job
Abhilekh runs its own logger line end to end — one manufacturer owns the chain from probe accuracy to the signed record.
- ▸PRB-SHT45-1M5 — cabled T+RH head for through-the-seal fridge duty
- ▸PRB-PT100-3W — Class-A immersion probe for buffered measurement
The ABH line is at the design-frozen, pre-production stage. Every battery-life, drop, thermal and IP figure is a calculated or simulated design estimate, and the regulatory marks referenced on this site are a certification roadmap — not held certificates.
Questions, answered
Other environments we monitor
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