Session: 13-13-01: Simulations of Material Modeling and Behavior Analysis for MEMS Applications

Paper Number: 144921

144921 - Comparison of Mechanical Behavior of Macro and Micro-Sized Ecoflex Mixtures 

Dynamic system applications such as soft robotics, energy harvesters, smart skin, wearable sensors, require highly stretchable elastomer materials. Ecoflex is a silicone elastomer that is increasing in demand but, the mechanical properties at the micro-scale for MEMS is not fully understood. Ecoflex also has different formulations which have varying properties and the material can be mixed with composites or varying ecoflex formulations to alter the mechanical properties. In this work, we illustrate the comparison of mechanical properties of macro and micro-sized samples by varying mixing ratios of two different formulations of Ecoflex (00-30 and 00-31). Material properties of produced samples are investigated by subjecting samples to batch-to-batch repeatability test, cyclic loading, visco-elastic behavior, Mullins effect and stress recovery test. Further, the scanning electron microscopy (SEM) method is used to examine the morphological structure of the fractured samples. Results demonstrate that the micro-sized samples exhibit higher stiffness in comparison to macro-sized samples.

Macro and micro-sized dog bone shape samples were prepared to examine the characteristics of the samples as illustrated in Fig. 1. Macro-sized dog bone samples were prepared adhering to American Society for Testing of Materials (ASTM-D412-C) standards. Weight ratios for mixing different Ecoflex shore hardness (Smooth-On Inc., USA) liquids were calculated based on the concentration: 25%, 50%, 75% and 100%. Various properties of fabricated macro and micro samples were recorded under uniaxial loading using a Stable Micro Systems texture analysis test frame (TA.XT Plus 100C). Initially, the paper compares the stress-strain property of Ecoflex shore hardness 00-30 and 00-31 under tension as represented in Fig 1b. Then visco-elastic behavior of the samples is studied under different speed rates. Further, two batches of 5 arrays of each Ecoflex sample are prepared to compare the variability during fabrication.  The paper also compares the mixing ratios of macro and micro-sized samples under cyclic loading, strain-softening, ultimate strength, and stress relaxation over time. Therefore, this work creates the database for the mechanical behavior of Ecoflex shore hardness 00-30 and 00-31 which guides the type of mixing ratio of Ecoflex to be used for appropriate smart material applications.

The results illustrate that micro-scale Ecoflex are stiffer and have less elongation to break than macro-scale using the same manufacturing process. The method of manufacturing the materials has a significant influence over the mechanical properties, such as temperature and mixing procedures. The results presented in this paper will aid researchers in designing MEMS devices using Ecoflex, and demonstrates how mixing multiple formulations of Ecoflex can be used to fine tune mechanical properties to meet specifications.

Presenting Author: Ranjith Janardhana University of New Mexico

Presenting Author Biography: Ranjith is a Ph.D Student at UNM working on acoustofluidics.

Authors:

Ranjith Janardhana University of New Mexico
Zeynel Guler University of New Mexico
Fazli Akram University of New Mexico
Nathan Jackson University of New Mexico