Novel analog switching circuit for van der Pauw measurements
  A simple electronic circuit is described using four common and very inexpensive analog multiplexer/demultiplexer chips. These analog switches are used to select eight different wiring configurations to a van der Pauw sample. Several interfacing schemes to a PC are suggested. The van der Pauw resistivity and Hall voltage expressions are also summarized. 
T. David, I. Molchadsky, A. Somechi, and R. Rosenbaum