Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 99888

99888 - Developing Electrically Equivalent Phantom Skull Using Pdms-Based Nanocomposites 

The long-term objective is to determine whether EEG can be used as a potential on-field sensor for detecting localized brain activity due to exposure to brain trauma. In principle, electrical signals from the interior of brain tissues are picked up by EEG electrodes after the signals are transmitted through various brain-skull-scalp layers. Most signals are lost when transmitted through the skull. Here, we are working to develop a synthetic “living” brain for studying the effectiveness of EEG as a health-monitoring sensor. Developing an electrically conductive skull layer is our goal in this study. Soft conductive composites have advanced our ability to create wearable and interactive artifacts. Polydimethylsiloxane (PDMS), a silicon-based polymer, is a common base composite used in developing conductive soft materials due to its non-toxicity, biocompatibility, high flexibility, elasticity, and high compressibility. These properties make PDMS a favorable candidate for creating stretchable electronics, particularly in biomedical applications such as the prototyping of phantom head models. However, PDMS is very low in electrical conductivity and unable to dissipate heat, which are both important design elements for creating sensing devices and wearable technology. For many years, researchers have explored the mechanics of PDMS and how conductive filler materials can alter the electrical properties of PDMS.  In the past, conductive filler materials that have been studied include carbon nanotubes, graphite, graphene, carbon black, and different types of metal particles. While many different filler materials can be combined with PDMS, the fabrication process of developing conductive PDMS is still time-consuming, difficult, and tedious as various factors can influence the outcome of the final product. Electrical conductivity values of conductive PDMS vary as different filler material concentrations are used as well as how efficiently the filler material bonds with PDMS. This study provides a relation between concentrations versus conductivity of varying concentrations of different conductive filler materials. The final result is provided in a schematic chart which users can use as a guide on the different concentrations of filler material. To show exemplary proof, an experimental study including a total of three types of conductive filler (CF) material, copper (CF₁), carbon fibers (CF₂), and graphite powder(CF₃) were combined with PDMS to obtain a desired electrical conductivity. This experimental study also analyzed the connection and comparison of conductivity values from a theoretical and experimental point of view. A comparison of the expected PDMS-based composite’s conductivity from the graph and its real conductivity is also provided. The ability to characterize different combinations of making PDMS-based composites will potentially shorten product production time and cost to find the right range of conductivity values. With the rapid development in soft material sensing devices, having a comparison of the different conductive filler materials allows users to choose the best conductivity option for their specific application. Further study can be conducted to expand the conductivity map with other filler materials to better understand the pattern of characteristics that can alter PDMS, which can then be applied to the fabrication of conductive soft materials with other types of polymer composites. 

Presenting Author: Tina Ko The University of Texas at Arlington

Presenting Author Biography: Ms. Tina Ko is an undergraduate in the Mechanical and Aerospace Engineering Department at The University of Texas at Arlington. Her research is related to sensors and material fabrication for traumatic brain injury applications. Currently, she is working in the field of composites and conductive soft materials with an emphasis on exploring electrical conductivity and impedance properties of fabricated materials.

Authors:

Tina Ko The University of Texas at Arlington
Yukti Shinglot The University of Texas at Arlington
Richie Ranaisa Daru The University of Texas at Arlington
Ashfaq Adnan The University of Texas at Arlington