Design of microgrippers based on amorphous-crystalline TiNiCu alloy with two-way shape memory

Amorphous-crystalline TiNiCu alloy ribbons at around 40 μm of thickness with an interface separating the amorphous and crystalline phases into layers were produced by melt spinning technique. It is shown that a decrease in the cooling rate of the melt from 8.9.10
⁵
to 4.2.10
⁵
K / s leads to an increase in the thickness of the crystalline layer from 2 to 10 μm, The ratio of the thicknesses of the amorphous d
_am
and crystalline d
_cr
layers was also varied by an electrochemical polishing method. Composite ribbons exhibited the two-way shape memory effect (TWSME) with bending deformation without additional thermomechanical processing. It was established that when the ratio d
_cr
/d
_am
is changed from 0.06 to 0.35, the minimum bending radius of the ribbon decreases from 37.1 to 6.3 mm, and the maximum reversible strain increases by 0.05% to 0.27%. The minimum time of the shape recovery of the ribbon during the realization of the TWSME when heated by an electric current pulse was 14 ms, and the force generated by the ribbon with a length of 3 mm in bending reached 1.2 mN. A series of the microgrippers (microtweezers) were fabricated on the basis of the composite ribbons with TWSME. The length of the clamping parts (arms) and the gap of the microtweezers can be adjusted in the range from 1.5 to 2.5 mm and from 10 to 500 μm, respectively, depending on the size of the processed micro-objects. Complete technological process of manipulating graphite filaments with a diameter of 5 to 25 μm using developed microgrippers was demonstrated.