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 mm
²
. 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.