Fabrication and characterization of an SU-8 gripper actuated by a shape memory alloy thin film

Abstract

In this paper, we present the fabrication process of a shape memory alloy (SMA) thin film in both monolithic and hybrid configurations. This provides an effective actuation part for a gripper made of SU-8 thick photoresist. We also extensively describe and discuss the assembly of the SMA thin film with the SU-8 mechanism. Measurements show that the SU-8 gripper is able to achieve an opening action of 500 μm in amplitude at a frequency of 1 Hz. Finite element model simulations indicate that a force of 50 mN, corresponding to 400 μm of opening amplitude, should be produced by the SMA actuator. Although the assembly of the TiNi SMA thin film with the SU-8 mechanism is demonstrated, the bond reliability needs further development in order to improve the thermal behavior of the interface. In this paper, we show that SU-8 is well suited as a structural material for microelectromechanical systems (MEMS) applications. An attractive feature in the MEMS design is that the SMA generated force is well matched with the elastic properties of SU-8. From the application point of view, a SMA-actuated SU-8 high-aspect-ratio microgripper can serve as a secure means to transport microelectronics device, because it provides good grasping and safe insulation. This is also a preliminary result for the future development of biogrippers.

Soft Robotics for Chemists

“…Pneumatically-driven flexible microactuators (FMAs) have been shown to be capable of bending, gripping, and manipulating objects [20][21][22][23] . Roboticists have explored scalable methods for gripping and manipulating objects at the micro and nano scales [24][25][26][27] . The use of compliant materials allows grippers to manipulate objects such as fruit [28] with varied geometry [29] .…”

Proton-Radiation Tolerance of Silicon and SU-8 as Structural Materials for High-Reliability MEMS

“…The curing reaction of the epoxy is initiated by exposure to UV, gamma-rays, or proton radiation which allows the fabrication of very high-aspect ratios and 3D-structures [9], [10]. Due to its biocompatibility and mechanical elasticity it is a candidate for microfluidics, sensing and actuating applications [11], [12]. Radiation tolerance in polymer MEMS devices is often very limited and large changes in the elasticity have been reported [13].…”

Design of a Piezoelectric-Actuated Microgripper With a Three-Stage Flexure-Based Amplification

“…[15] and Roch at al. [16] for microgrippers, but short lifetime, hysteresis and high response time limit their further applications. Due to the inherent advantages such as high force output to weight ratio, fast response and zero backlash, piezoelectric(PZT) actuators have been widely used in precision positioning system and microgrippers [17]- [19], and good performance can be achieved with proper control of such kinds of piezoelectric actuated systems [20]- [22].…”