Three-axis Hall transducer based on semiconductor microtubes
  A three-axis Hall transducer based on GaAs/AlGaAs/InGaAs microtubes has been fabricated. The possibility of simultaneous measurement of all the three magnetic field components with such a transducer was demonstrated. It was also shown possible to pack the free-standing parts of the transducer with polydimethylsiloxane for protection of those parts from mechanical actions. 
Alexander Vorob'ev, Anton Chesnitskiy, Alexander Toropov, and Victor   Prinz
cond-mat.mes-hall physics.ins-det