Designed to monitor room temperature and air humidity to ensure optimal operating conditions and work environments, the ISL125A is battery powered, wireless and simple to install at any location. The ISL125A is available either as an NB-IoT device. 

  • Assists in ensuring optimal operating conditions in room environments
  • Battery powered
  • Wireless
  • Able to work in remote locations 
  • High and low thresholds, hysteresis and actions configurable by end user for edge intelligence
  • Range up to 10km line-of-sight
  • Either internal or external antenna
  • Configurable measure internal 
  • Configurable transmit interval for each mode 
105A - 45 Deg


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Long Battery Life

Our sensors have been designed to have a battery life of up to 10 years, so you don't have to worry about changing them frequently.


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Proactive Alarm System

Pro-active alerts ensure that your team can prevent temperatures breaching critical levels, and so safeguard patient well-being.


Improved Patient Safety

By ensuring that your medical fridges are always at the correct temperature, you improve the potency and reliability of medications and vaccines.

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Real-Time Online

Together with Real-time Online, the sensors enable constant monitoring, deliver pro-active alerts on threshold breaches and generate bespoke reports.

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Simple Set-Up

Pro-active alerts ensure that your team can prevent temperatures breaching critical levels, and so safeguard patient well-being.


Low Costs

Choosing wireless sensors and a cloud platform enables you to reduce your installation and maintenance costs.



Configurable high/low thresholds allow different transmit intervals when thresholds are crossed providing advanced edge intelligence to the network, and enable alarms to be generated by Realtime-Online™.


Data from every sensor in your network is reported back through Invisible Systems Big Data architecture either to our Monitoring and Analytics platform Realtime-Online™, or to a partner cloud platform via our API, ensuring that your data is visible, actionable and valuable to your organisation.


NB-IoT is a standards-based narrowband Low Power Wide Area (LPWA) technology developed to enable a wide range of new IoT devices and services. NB-IoT devices connect directly to the cellular mobile network via a low-cost SIM card. NB-IoT significantly improves the power consumption of user devices, system capacity and spectrum efficiency. 



Band: 1, 3, 5, 8, 20, 28

Expected range (line of sight): Up to 10km

Power: 23dBm ± 2dB


CE, other regions available on request


Dimensions (mm): 95x70x40

Enclosure colour: White

Enclosure plastic type: ABS

Operating Temp Range: -20°C to +60°C

Operating Humidity Range: 30% RH to 90% RH

Battery: 1 x C-cell (8500 mAh)

Batteries type: Lithium Thionyl Chloride (Non rechargeable)

Expected battery life, 15 min Tx interval: Up to 3 years

Expected battery life, 6 hour Tx interval: Up to 10 years

Operating lifetime: Up to 10 years

Power type: Battery 3.6VDC


Measurement interval range: 30 secs - 60 mins

Tx interval range (multiple of measure intervals): 1 min - 6 hours



Measurement Range: -20°C to +60°C


Resolution/Step-size: 0.1°C

Drift: < 0.02 oC/yr

Sensor characteristics: Digital

Calibration: Optional



Measurement Range: 0RH to 100% RH

Accuracy: ±2°C

Resolution/Step-size: 0.5%RH

Drift: < 0.25% RH/yr

Sensor characteristics: Digital

Calibration: Optional


Download Datasheet
We wanted to use the IoT approach to technology using a device placed in a fridge to allow us to continually monitor temperature, but also to flag up where breaches occur so we can respond to them then and there. We now have evidence to show that, 24 hours a day, our vaccines are being stored at the correct temperature Paul Brown, NHS Suffolk Primary Care
We were looking for a wireless system, one that allowed all users to log on from off-site, was flexible enough to allow grouping per PI of units and didn’t need dedicated server hardware/networking. The trial of the system was so simple and impressive that we kept it. Royal Holloway University
Invisible Systems solution is so easy to install, there is no need to interfere with other IT services. It was a non-invasive install and that was a primary factor in selecting it. I can log in from home, from holiday - it’s very user friendly. Noel Gavin, Maynooth University