Characterizing Spider Glue Properties by Manipulation of Large Glue Volumes

Student: Aaina Gupta
Mentors: Ali Dhinojwala (University of Akron), Gaurav Amarpuri (University of Akron), and Dharamdeep Jain (University of Akron)

Many commercial glues that are used today become less sticky under high humidities. We are studying spider glue, which is known to become stickier as the humidity increases, so ultimately a commercial glue can be produced. To study only the glue properties, an apparatus was used to transfer the glue to a substrate. This was done to study the surface energy and other properties of the spider glue.

Many commercial glues that have been developed have a one thing in common: the reduction of adherence under high humidity environment.  However, spider species catch insects using glue even under humid conditions. We studied Larinioides cornutus, an orb spider. Throughout the different sectors of the web, there are glue droplets that are very similar in size and evenly spaced. It is important to study the properties of the glue because it will allow us to develop a commercial glue with similar properties. Spider glue consists of both low molecular weight molecules, proteins, and water. The glue on the underlying flagelliform can be described as a bead on a string and both are made up of different proteins, which makes it difficult to analyze the properties of the glue alone. My project this summer sought out the problem of transferring the glue to a substrate to collect the glue in bulk quantities, something that has not been reported in literature before, for analysis without the flagelliform transferring. From recent studies, it was found that at high humidity the fluidity of the glue increases and allows the glue to properly adhere to different surfaces. Through many modifications, I was able to make an apparatus that allowed for the glue transfer at high humidity. By comparing the control (untouched) slide with glue slide, it was concluded that the glue had transferred successfully to the substrate. This was able to occur because the glue has a property known as cohesive failure. This means that at high humidity some portions of the glue would transfer to the substrate, while some would stay on the spider silk (more than 50% would transfer). With the success of the transfer, we had the ability to analyze the properties of the glue further. Through the help of other colleagues in the lab, we can further test the surface energy of the glue through JKR and quantify the viscoelasticity of the glue through particles transfer.