Measuring the Load-Carrying Capability of IPMC Microgripper Fingers

The goal of this work is to develop a microgripper using ionic polymer metal composite (IPMC), an electroactive material, and to understand the relationship between finger shape and load-carrying capability. This microgripper supports manipulation of rigid and flexible objects in wet and dry environments. The paper first describes the design of the microgripper, which consists of a "pincher" mechanism that holds the IPMC fingers. Two finger shapes are considered. The first shape, denoted as "straight" fingers, is tested for load-carrying capability by picking up pre-weighed micro-balls of solder. Since IPMC is a compliant material, it was expected that shorter length fingers would carry more load. We found experimentally a linear relationship between finger length and load-carrying capability. The second finger shape is tapered. This finger shape was compared with the straight fingers by measuring the load-carrying performance of several different sizes of each finger shape. It was found that shape has a relatively minor effect. The load-carrying capability was found to be related primarily to the area of the finger. Thus, the microgripper finger shape should be chosen based on the ease of manufacturing. In terms of total strength, it was noted that the microgripper carried loads that exceed the weight of the fingers by a factor of seven