Review of Applications of Energy Harvesting for Autonomous Wireless Sensor Nodes

Energy Harvester And Its Need In Wsns

Energy harvesters are energy transducers that generate negligible amount of electrical energy from the ambient energy sources available around the wireless sensor nodes and power them (STMicroelectronics 2013). Over the years, the cost of sensors has drastically decreased from an average of $1.30 to 60 cents per sensor as reported by Goldman Sachs (Jankowski et al. 2014) and is assumed to continuously decrease in the future thus fueling the deployment of smart sensors everywhere as envisioned in the concept of internet of things (IoT).

A typical smart WSN is as shown in the Fig.1 (a). It comprises of a microcontroller for processing sensor data, wireless antenna, a single sensor or range of sensors and battery. The new concept for IoT is to replace the battery with an energy harvester and rechargeable battery as shown in Fig.1 (b). Also, the microcontroller is replaced by the ultra-low powered microcontrollers such as MSP430 (Borgeson 2012) or the STM8L/32L series (STMicroelectronics 2017), thus reducing the power consumption. The power required for such sensor is less and intermittent.

Figure 1.

Schematic of smart wireless sensor nodes (a) traditional smart wireless sensor node (b) modern IoT ready self-powered smart WSN.

3. Role Of Energy Harvesters In Low-Power Computing

There are two perspectives on achieving energy efficiency in computing devices. One is to reduce the energy consumption using LP and ULP circuits and devices. Another strategy is to integrate auxiliary energy providing devices such as energy harvesters to the existing computing circuits. Often, both the energy efficiency must work in tandem to achieve the power optimization goals and deliver the required power that will suffice for both normal and ad-hoc computing requirements of the deployed computing devices.