TECHNICAL PAPER Fluid load augmented micro balance Keshava Praveena Neriya Hegade 1 • Muthukumaran Packirisamy 1 • Rama Bhat 1 Received: 31 July 2018 / Accepted: 29 December 2018 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Micro-cantilever based micro weighing balance was studied using polydimethylsiloxane micro-cantilever beam and water droplet. In this system, micro-cantilever beam acts as spring balance while the droplet acts as weight. Initially, tip defection of cantilever beam under the body load provided by water droplets of sizes 4, 5, 6 and 7 ll were found experimentally. For this study, droplets were placed at dimensionless length n = 0.8 from the clamped end. Fluid load augmentation was studied by studying the tip deflection of the beam with droplet under flow velocities between 0.75 and 1.5 m/s. A mini wind tunnel is used to provide fluid load with wind flow occurring along the length of the beam. Experimental results show an increase in tip deflection with flow velocity, suggesting the phenomena of fluid load augmentation. In addition to experimental results, this paper presents details on modelling of natural frequency of the micro-cantilever beam with added mass using Rayleigh’s energy method. 1 Introduction Over the years, weighing balance has been adapted into several designs and modifications yielding reasonably good improvements in performance. For measuring lighter objects, a micro weighing scale can be suitably used. However, measuring extremely lighter samples, in lg ranges, becomes difficult with conventional method of spring based weighing balance as they reach limitations in precision. Thus a micro-cantilever based weighing balance for detecting slight mass changes is studied and their details are explained. The sensitivity of the spring governs the range of a weighing balance. It is comparable to sen- sitivity of the beam in a cantilever based weighing balance. The sensitivity of the beam can be increased by increasing the deflection of the beam for a given load. Several methods have been proposed to enhance the deflection of the beam such as changing the dimensions, changing shape of the beam (Khaled and Vafai 2011, 2013; Khaled et al. 2003). Khaled et al. (2003) studied advantages of modified beams in epsilon shape. They have studied the deflection of micro-cantilever beam under fluid flow. Turbulence in the flow creates disturbances in the beam. The epsilon beam possesses large effective stiffness making the beam stable under flow turbulence. Large deflection is observed in the center beam in e beam assembly. In addition Khaled and Vafai (2011) performed analytical and numerical studies to find the deflection of cantilever beams. Three types of the beam were considered for the study. A regular rectangular beam modified triangular beam and epsilon beam. These beams were subjected to different types of load concentrated force, concentrated moment and constant surface stress. It was reported that the deflection values of modified triangular beam and the epsilon beam are 280% above than deflection values of a regular rectangular beam under concentrated moment and 425% above the beam deflection values of regular rectangular beam for surface stress load. The deflection at the free end of the interme- diate epsilon beam is 200% above the deflection values of modified triangular beam. Zhang et al. (2011) studied analytically the deflection and resonant frequency of 12 geometrically distinct micro-cantilever beams. These geometry modifications were carried out to study the effect of mass near the free end and the effect of clamping width at the fixed end. It can be concluded from this study that minimizing effective mass near the free end and reducing & Muthukumaran Packirisamy pmuthu@alcor.concordia.ca http://www.mie.concordia.ca/mems Keshava Praveena Neriya Hegade k_neriya@encs.concordia.ca Rama Bhat rama.bhat@concordia.ca 1 Optical Bio-Microsystems Laboratory, Department of Mechanical and Industrial Engineering, Concordia University, EV4-149, 1515 St. Catherine St. West EV13.235, Montreal, Que ´bec H3G 1M8, Canada 123 Microsystem Technologies https://doi.org/10.1007/s00542-018-04289-9