“…Reproduced with permission from Elsevier. Gonzalez-Guerrero et al, 2013;Lee and Kjeang, 2010;Lim and Palmore, 2007;Reid et al, 2013;Togo et al, 2007Togo et al, , 2008Zebda et al, 2009aZebda et al, , 2009bZebda et al, , 2010, and paper-based biofuel cells (Narváez Villarrubia et al, 2014;Shitanda et al, 2013;Zhang et al, 2012). Most of these designs were focused on minimizing the internal resistance of the fuel cell compared to the traditional H-cell systems of early years.…”