Biofluid Activated Microbattery for Disposable Microsystems

A flexible aluminum-silver oxide microbattery activated by a liquid electrolyte for on-demand operation is presented. Four different electrolytes are tested: 1) aqueous sodium hydroxide; 2) blood; 3) urine; and 4) saliva. To start the operation of the microbattery 8 μL of the target electrolyte is pipetted onto the surface of the microbattery. The microbattery is fabricated on a polyimide substrate using conventional microfabrication techniques. The proposed microbatteries have an interdigitated electrode geometry and a minimum footprint area of 12 mm2. Seven different batteries designs having different electrode width and spacing have been fabricated and characterized. The experimental results show energy densities up to 26.6 μW h cm-2μm-1, maximum voltage output of 1.75 V, maximum current output of 0.55 mA, maximum capacity of 7.17 μAh, and maximum operating time of 75 min.