I'd like to actually measure this, but I forget when I'm in lab. The
whole fluid chamber is about a centimeter in diameter, so 3 mm seems
like a safe upper bound.
insulation (TT), type E metals (chromel--constantan), number 30 AWG
wires ($0.255\U{mm}$ diameter), in a $72\U{inch}$ length.}. The
thermocouple is inserted through one of the ports in the AFM fluid
-cell, so the thermocouple tip is in the buffer less than $TODO\U{mm}$
-from the cantilever tip.
+cell, so the thermocouple tip is in the buffer less than $3\U{mm}$
+from the cantilever tip.% TODO: measure distance
\Cref{eq:kappa} depends on the \emph{absolute} temperature, so labs
without easy access to a thermocouple can probably get away with