Seebeck Effect

Edit and compile if you like:

\documentclass{standalone}

\usepackage{circuitikz}
\usetikzlibrary{3d,positioning,decorations.markings}

\tikzset{
decoration={%
  markings,%
  mark=at position 0.05 with {\arrow[black]{stealth};},%
  mark=at position 0.4 with {\arrow[black]{stealth};},%
  mark=at position 0.6 with {\arrow[black]{stealth};},%
  mark=at position 0.95 with {\arrow[black]{stealth};}},
gradient/.style ={bottom color=blue!50, top color=red},
pics/.cd,
  p charge/.style={code={
      \node [fill=orange, shape=circle, inner sep=0pt] (pc) {+};
      \draw[thick,->] (pc)--++(0,-0.5);
  }},
  n charge/.style={code={
      \node [fill=cyan, shape=circle, inner sep=1pt, scale=1.2] (nc) {-};
      \draw[thick,->] (nc)--++(0,-0.5);
  }},
}

\newcommand\heatsink{
  \draw[fill=blue] (0,0,0) rectangle ++(6,1.5,0)node[midway,color=white]{heat sink};
  \draw[fill=blue] (6,0,0) -- ++(0,1.5,0) -- ++(0,0,-3) -- ++(0,-1.5,0) -- cycle;
  \draw[fill=blue] (0,1.5,0) -- ++(6,0,0) -- ++(0,0,-3) -- ++(-6,0,0) -- cycle;

  \draw[gradient,opacity=0.5] (0.5,1.5,-2.8) -- ++(0,10,0);
  \draw[gradient,opacity=0.5] (0.5,1.5,-2.8) -- ++(5,0,0);
}

\begin{document}
\begin{circuitikz}[scale=0.4,font=\sffamily,>=stealth]

  \begin{scope}
    % heat sink 1
    \heatsink
    \draw[gradient,opacity=0.5] (0.5,1.5,-2.8) -- ++(0,0,2.6);
    \fill[gradient,opacity=0.7] (5.5,1.5,-0.2) -- ++(0,10,0) -- ++(0,0,-2.6) -- ++(0,-10,0) -- cycle;
    \fill[gradient,opacity=0.7] (0.5,1.5,-0.2) rectangle ++(5,10,0)node[midway,draw,circle,white] (N) {N};
    \pic[below left=8mm and 3mm] at (N) {n charge};
    \pic[below right=7mm and 6mm] at (N) {n charge};
    \pic[above left=1cm and 3mm] at (N) {n charge};
    \pic[above right=1cm and 5mm] at (N) {n charge};
  \end{scope}

  \begin{scope}[xshift=15cm]
    % heat sink 2
    \heatsink
    \draw[gradient,opacity=0.5] (0.5,1.5,-2.8) -- ++(0,0,2.6);
    \fill[gradient,opacity=0.7] (5.5,1.5,-0.2) -- ++(0,10,0) -- ++(0,0,-2.6) -- ++(0,-10,0) -- cycle;
    \fill[gradient,opacity=0.7] (0.5,1.5,-0.2) rectangle ++(5,10,0)node[midway,draw,circle,white] (P) {P};
    \pic[below left=8mm and 3mm] at (P) {p charge};
    \pic[below right=7mm and 6mm] at (P) {p charge};
    \pic[above left=1cm and 3mm] at (P) {p charge};
    \pic[above right=1cm and 5mm] at (P) {p charge};
  \end{scope}

  % heat source
  \draw[fill=red] (0,11.5,0) rectangle ++(21,1.5,0) node[midway,white] (J) {$J\longrightarrow$};
  \draw[fill=red] (21,11.5,0) -- ++(0,1.5,0) -- ++(0,0,-3) -- ++(0,-1.5,0) -- cycle;
  \draw[fill=red] (0,13,0) -- ++(21,0,0) node[color=white,above right=0 and -5mm,pos=0.5]{heat source} -- ++(0,0,-3) -- ++(-21,0,0) -- cycle;

  % electric field
  \node[below=1cm,scale=1.3,align=center] at (11,11.5) {electric\\field};
  \draw[thick,-stealth] (6.8,10,-1.5) node[below right=1mm]{+} -- ++(0,-7,0)node[above right=1mm,scale=1.2]{--};
  \draw[thick,-stealth] (14.1,3,-1.5) node[above left=1mm]{+} -- ++(0,7,0)node[below left=1mm,scale=1.2]{--};

  % resistor
  \draw[postaction={decorate}] (21,0.75,-1.5) -- ++ (3,0,0) -- ++(0,-3,0) to[R] ++ (-27,0,0) |- (0,0.75,0);

\end{circuitikz}
\end{document}