TECHNICAL PAPER Essential design and fabrication considerations for the reliable performance of an electrothermal MEMS microgripper Marija Cauchi 1 • Ivan Grech 2 • Bertram Mallia 3 • Pierluigi Mollicone 1 • Barnaby Portelli 2 • Nicholas Sammut 2 Received: 31 August 2018 / Accepted: 19 February 2019 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Over the past years, microelectromechanical systems (MEMS) have become a vital component within a wide range of technologies, making the study of their performance and operational reliability a very critical aspect for their correct functionality. Microgrippers are one such type of MEMS devices with one of their key applications being the manipulation of biological tissues and cells. This paper presents a microgripper design based on the ‘hot and cold arm’ electrothermal actuation mechanism that is suitable to study the deformability properties of human red blood cells under healthy and pathological conditions. The main scope of this paper is to highlight a number of failure mechanisms that are typical of surface micromachined MEMS microgrippers. These include out-of-plane buckling of the hot arm, stress concentrations, device stiction, and residual stresses. The studied polysilicon microgripper structures were designed and fabricated in line with the specifications of the commercial fabrication process PolyMUMPs TM . The microgripper design was numerically modelled and electrothermomechanically studied using finite element analysis in CoventorWare r . Experimental testing on the fabricated structures was used to demonstrate reliable microgripper performance as well as instances of the considered failure mechanisms. Results for the reliable microgripper performance show that the microgripper arms deflected as expected when actuated, with the obtained simulation and experimental results in good agreement. The investigated failure mechanisms have led to the identification of essential design and fabrication considerations whose thorough investigation, with the aid of appropriate modelling approaches, is essential to define improvement solutions and best practices to mitigate the failure or malfunction of the microgripper during operation. 1 Introduction Microgrippers are typical microelectromechanical systems (MEMS) widely used in microassembly and micromanipu- lation fields. They play critical roles in the handling and positioning of micromechanical parts (Ivanova et al. 2006; Zhang et al. 2010), as well as in the safe manipulation and characterisation of tissues and cells within the biomedical field (Di Giamberardino et al. 2017; Iamoni and Soma` 2014; Kim et al. 2008; Potrich et al. 2018; Zhang et al. 2013). Such working environments make it very important to study the performance and operational reliability of MEMS microgrippers. Previous works on MEMS microgrippers have focused on the optimisation of their design and kine- matic structure (Verotti et al. 2017), the structural materials used (Cauchi et al. 2018a; Nguyen et al. 2004), the actua- tion and sensing mechanisms (Yang and Xu 2017), the operational requirements and limitations (Dochshanov et al. 2017), the fabrication process used (Bagolini et al. 2017; Cauchi et al. 2018b; Feng et al. 2016; Kim et al. 1992), and the working environment in which they will be operated (Chronis and Lee 2005). This paper is an extension of the work originally presented in Cauchi et al. (2018c). It discusses in detail a number of failure mechanisms associated with surface micromachined MEMS microgrippers and presents proposed considerations at the design and fabrication stages to mitigate the & Marija Cauchi mcauc03@um.edu.mt 1 Department of Mechanical Engineering, Faculty of Engineering, University of Malta, Msida MSD 2080, Malta 2 Department of Microelectronics and Nanoelectronics, Faculty of Information and Communication Technology, University of Malta, Msida MSD 2080, Malta 3 Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Malta, Msida MSD 2080, Malta 123 Microsystem Technologies https://doi.org/10.1007/s00542-019-04363-w