Microbial fuel cells (MFCs) are bio-electrochemical devices that produce electrical current from the electrochemically active bacteria (EABs). These bacteria generate the electrons from the degraded organic matter and harness renewable and pollution-free energy in a self-sustaining manner. Due to its user-friendly architecture, neutral pH, simple operating conditions and amenability to integrate with the on-chip technology, MFCs are the economical and convenient alternative to conventional power sources. Since the first development of MFC, an ample amount of studies have been reported especially to harness new bacteria types, inoculation protocols, and cell and bioelectrode fabrication methodologies. As a result, several MFCs have been successfully developed as a biosensor and power hub by utilizing various fluid resources, such as domestic and industrial wastewater, urine, and soiled water from sewage. However, in order to be commercially viable, the device architecture and size of the MFCs become the essential parameter for power generation, which decides the potential application. In this context, several micro-scale MFC architectures have been proposed. Among these, the paper-based microfluidic fuel cell technology has drawn remarkable attention due to its inexpensive and inherent fluid flow capillary action properties. In addition, wide array (series/parallel) configurations have been incorporated to further enhance the power output.
With these MFCs, a extensive range of applications, such as powering LEDs, digital thermometer, wireless, sensors, radio nodes etc., have been successfully demonstrated. With this flexibility and unique features, paper-based MFCs have the ability to monitor the on-field parameter (temperature, humidity, hazardous gas etc.) using the Internet of Things (IoT) cloud network. Currently, The Internet of Things (IoT) technology is the most popular technology in the field of wireless data transmission with IoT cloud. It connects various devices and their protocols over internet infrastructure which can be monitored, analyzed, and controlled remotely over the internet. It has an immense application in the field of healthcare, agriculture, automotive, and remote sensing sectors.
In this study, as a proof of concept, the Shewanella putrefaciens powered stacked origami MFCs have been demonstrated to drive an ultra-low-power (ULP) IoT node to measure the on-field ambient temperature and transmit corresponding data to a mobile phone. The IoT node requires 2.5–3.3 volt for proper operation, therefore a DC-DC booster was used just after the fuel cell to step-up the low voltage. This step-up voltage was further stored in the supercapacitor to supply power to the IoT node in case of a high current requirement. Finally, after powering the IoT node, it sends the temperature data over low-power Bluetooth low energy (BLE) that can be observed by any smartphone supporting Bluetooth 4.0 and nRF connect android app. The detailed stepwise integrated block diagram from MFC to a mobile phone has been displayed in Figure 1. The proposed approach offers autonomous environmental monitoring using paper-based MFC as a viable substitute for conventional power sources.
Figure 1: Block diagram of complete setup MFCs powering IoT node which communicates to smartphone and IoT cloud servers
Figure 1
