We present a way to fabricate microgrippers that can meet the industry's needs well, i.e., low cost and large tip deflection, etc. The microgripper is fabricated by bonding two identical micro NiTi-Si cantilever beams together with a silicon spacer in between. It can be actuated by electrical current directly. We have tested the behavior of micro NiTi-Si cantilever beams of three different sizes, and compared that with our simulation results. According to our simulation, the maximum strain and the maximum stress in NiTi should enable the grippers to survive after 106 cycles. Due to the simple fabrication process, this design is very suitable for batch production at low cost, which is a significant advantage in both medical and manufacturing industries
A simple method is proposed for simulating the behavior of shape memory alloys at grain level. Different from many previous models in the literature, this model is applicable for not only proportional load at a constant temperature but also complicate non-proportional load together with temperature variation. The capability of this model is demonstrated by simulating the strain response of a set of combined tensile-shear stress loading.
Surface relief is one of the interesting properties of shape memory alloys. In this paper, we investigate the surface roughness of NiTi shape memory alloys polished in austenite and twinned martensite phases using a Wyko interferometer. The potential application of surface relief in shape memory alloys as a kind of novel micro mirror is proposed.
In this paper, we present the results of theoretical study of thin film technique based micro grippers. Three most popular actuation mechanisms, namely, piezoelectric, bimetal and shape memory alloy are investigated. First, we present the simulation results against the measured behavior of NiTi shape memory alloy thin film based micro grippers. Then we compare the performances of these three kinds of micro grippers. It shows that shape memory alloy based micro gripper is much better than the others.
In this paper, we present a way to fabricate microgripper that could well meet the industry needs, i.e. low cost, high performance etc. A medium sized microgripper of 1.6 mm in length has been fabricated, tested and simulated. This novel design, with its fabrication process, makes it possible for batch production, which results in lower production cost. Its low cost has unique advantages in both medical and manufacturing industries. For example, in the medical field, the microgripper could be disposed after every use, much like a syringe without imposing excessive costs. Our finite element simulation agrees reasonably well with the measured behavior.
In this paper, a novel micro assembly method using Shape Memory Alloy (SMA) is investigated. The principle of this method and its advantages are briefly discussed. A finite element package, ANSYS, is used to simulate the whole assembly process. A special material element is used for modeling the behavior of SMA.