Silvanet Wildfire Sensor

The Silvanet Sensor monitors temperature, humidity and air pressure and detects forest fires during the early stage of the fire.

Silvanet Wildfire sensors are attached directly to trees to detect environmental air quality within a radius of 80 m to 100 m (260 ft to 320 ft). These solar powered devices monitor the microclimate of the forest using a Bosch gas sensor with a Machine Learning model to detect the presence of a smoldering fire within range of the sensor.

Key features

• Bosch gas sensor

  The sensor includes a Bosch gas sensor that combines ultra-low-power Air Quality sensing with a precise gas sensing mode. Carbon monoxide, hydrogen and VOCs (Volatile Organic Compounds) are detected at the ppm level with built-in artificial intelligence (AI) to reliably detect a fire and avoid false positives.

• LoRa/LoRaWAN connectivity

  Connectivity to the Silvanet Network is provided by a LoRA-integrated radio to send and receive messages via a robust LoRaWAN mesh network within a large forest environment. This allows the sensors to connect to distributed LoRaWAN-enabled Silvanet Mesh Gateways and Border Gateways.

• Solar powered

  Power is supplied by a built-in solar panel to allow the sensor to run maintenance-free for 10 to 15 years without the need of batteries. As a precaution against the device itself starting a fire, it stores its energy in supercapacitors rather than batteries. This avoids the use of lithium and other toxic materials. A loop allows it to be attached directly to trees using treenails or garden wire (temporary use only).

Delivered components

Each shipment of a sensors includes the following components:

• Ten Silvanet Wildfire Sensors

• Ten treenails

• Ten spacers

Dimensions and weight

The dimensions of the Silvanet sensor are (LxWxH) 19 cm x 9.2 cm x 1.34 cm. The sensor weighs 136 g.

Bosch gas sensor

The Silvanet Wildfire sensor uses the the Bosch gas sensor to monitor the microclimate of the forest. It is a low-energy hydrogen sensor that detects the presence of a smoldering fire over distances of up to 115 m.

This gas sensor detects the presence of Volatile Organic Compounds (VoCs) and Volatile Sulfur Compounds (VSC) and detects these compounds at <20 ppm.

Environmental detection

The gas sensor can detect CO (Carbon Monoxide), H₂, (Hydrogen) and VOC (Volatile Organic Compounds). It measures the environment's temperature, humidity and air pressure. It also monitors the microclimate of the forest by reading the following environmental values:

• Air pressure: pressure in Pa

• Humidity: relative humidity

• Temperature: temperature in Celsius

Measurement conditions

In the Silvanet sensor, the gas sensor provides measurements under the following conditions:

• Air pressure: 300hPa to 11000 hPa

• Humidity: 0% to 100%

• Temperature: -40°C to 85°C

Power consumption

The Silvanet sensor has very low energy consumption which is provided by its built-in solar panel. As a precaution against the device itself starting a fire, the sensor stores its energy in supercapacitors rather than batteries.

The two key components that consume energy are the gas sensor and the LoRa radio. The gas sensor consumes ~3.9 mA in standard gas scan mode. The radio consumes 7W of energy to operate so it can continue to operate in a shaded location for ~6 hrs.

Power supply

The sensor requires sufficient energy to support continuous operation over a 24-hr. period while still having enough reserve power to support the heating and powering of the gas sensor and to send a burst of messages when a fire is detected.

Idle/active modes

Normally, the Silvanet Sensor Node is in idle mode. It activates every 60 seconds to read the air quality / gas sensor and every 2 hours to read the environment. It then sends a single packet to the Silvanet Server via the Mesh Gateway and Border Gateway. These data packets contain normal (non-fire detection) environmental data which includes temperature, pressure and humidity internal values. These values are displayed in the Site Management app.

Built-in solar panel

The sensor includes a 60 mm x 60 mm solar cell on its front housing. It continuously generates energy during the daytime and recharges the device with sufficient power for the next 24 hours. After sunset, it begins to discharge until sunrise. After sunrise, it begins to recharge to 100% within about an hour.

Each day the solar panel harvests 7 W in the constrained conditions of a forest.

Supercapacitor Energy Storage

The Silvanet sensor uses a set of supercapacitors to store energy for use by the radio, gas sensor and other components. It stores the energy for day-to-day tasks and has a reasonable amount of reserve power to operate the gas sensor and radio module in case a potential fire is detected. As supercapacitors have an expected lifespan of 10 years or more, the sensors are essentially maintenance free. This allows for an expected lifespan of the sensor between 10 and 15 years.

Supercapacitors have a high capacity but a small maximum voltage of 2.7 V so a series of capacitors are loaded to 4 V. Capacitors are fully charged to 5.2 V.

Additional resources

• Sensor ratios and ranges

• Sensor density

• Deploy sensors

• Deployment verification