  We propose a new scheme aimed at cooling nanostructures to microkelvin
temperatures, based on the well established technique of adiabatic nuclear
demagnetization: we attach each device measurement lead to an individual
nuclear refrigerator, allowing efficient thermal contact to a microkelvin bath.
On a prototype consisting of a parallel network of nuclear refrigerators,
temperatures of $\sim 1\,$mK simultaneously on ten measurement leads have been
reached upon demagnetization, thus completing the first steps toward ultracold
nanostructures.
