Urine Powered Battery (UPB) for low power sensors

In this paper, the Urine Powered Battery (UPB) has been designed and proposed for driving low power sensor applications. In UPB, human liquid waste-urine has been utilised as a source of energy extraction. The natural neat human urine has been used as an electrolyte in the design. The proposed UPB consists of hybrid (series and parallel) combination of small single chamber Urine Powered Cells (UPC´s). In Urine Powered Cell, the electrodes have been dipped in urine and potential across the electrodes has been measured. The single UPC is a membrane less single chamber cell. The selection of materials for electrodes, amount of urine per cell, number of urine powered cells in each row and number of rows to be connected in parallel are some of the important aspects of UPB design. It has been observed that the best combination of electrode materials (cathode-anode) is Cu-Zn, respectively. The single chamber UPC, having Cu-Zn electrode combination is capable of generating voltage of 0.75V. The hybrid combination of UPC´s has been employed to obtain the sufficient output voltage and current required to drive low power applications. However, the load regulation of UPB is poor. A step down DC/DC convertor LTC3388-3 has been employed which provides well regulated constant output voltage of 5.0V and sufficient current of 3mA to 4mA to drive the system. In the proposed design, the LDR (Light Dependent Resistor) has been used as low power sensor, driven by UPB which is further capable of driving automated lighting system.