\begin{tikzpicture}
    
  ode at (0,0) {\includegraphics[height=4.25cm]{sensorhygro}};
    \draw[-latex] (1.75,-0.1) -- (2.,-.75);
    
  ode at (2.,-.75) [below]{sensor};
    
    \draw[-latex] (-1.5,-0.1) -- (-1.75,-.5);
    
  ode at (-1.75,-.6) [below]{measurement};
    
    
  ode at (1,-2.2) {transponder};
  \end{tikzpicture}