sf=1;
 lm=length(cho);
    i=0:1:lm-1;
    
    set(gcf,'Name','Oxygen WAVE');
    h1=plot(i/sf,cho,'b');
    ylabel('blood');
    xlabel('time(s)');
    title('Oxygen WAVE');
    grid on;
    set(gca,'NextPlot','replacechildren');