Stretchable Conductive Elastomers for Soldier Biosensing Applications: Final Report
Technical Report,01 Oct 2012,01 Sep 2015
US Army Research Laboratory Aberdeen Proving Ground United States
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In this report, we communicate the results of a 3-year US Army Research Laboratory Directors Research Initiative project focused on exploring the feasibility of using engineered conducting elastomer materials for interfacing to the human body to collect brain electroencephalographic EEG signals. We present a carbon-nanofiber-filled polydimethylsiloxane conductive elastomer material solution CNF-PDMS whose electrical impedance can be tuned over more than 4 orders of magnitude and which exhibits a flat electrical impedance shift when subjected to quasi-static compressive strains exceeding 60 . We present experimental results for our conductive elastomer used as a substrate for EEG measurement that indicate signal transmission remains intact when subjected to large compressions in excess of 60 . Specifically, although there is degraded signal-to-noise ratio SNR with lower CNF fill ratios, the single-channel hierarchical discriminant component analysis classifier of EEG data acquired using the CNF-PDMS indicates adequate performance across a wide range of compressive strains. Furthermore, we present a purpose-built modular and open-architecture EEG signal-processing board, which we have integrated with a dedicated network analyzer chip for exploring the efficacy of using real-time impedance monitoring for EEG error rejection under field conditions.