I am aware of at least one large hardwood lumber company here in NC that uses the lignomat control system (there may be more). If my memory serves me correctly, I believe they are using pins to measure MC (measures electrical resistance to estimate MC) of the sample boards. Rather than the more common dry bulb / wet bulb, this lignomat control system is using cellulosic wafers to measure the EMC (equilibrium moisture content) conditions in the kiln.