Development and analysis of stretchable electronics in biopotential monitoring

In this Thesis, stretchable electronics are studied and developed, with a focus on the epidermal monitoring of biopotentials for healthcare and other applications. Conventional manufacturing processes for stretchable electronics are time and cost intensive. A novel manufacturing method to create stretchable electronics is developed, in which a cutter plotter is used to directly shape thin metal films, in order to produce stretchable designs. The limits of the manufacturing process are investigated and recorded, both in terms of the cutter plotter capabilities and in the use of different materials and substrates for the thin-film device. The thin, stretchable devices are also tested in a wide variety of data collection situations, including measuring of a variety of biopotentials including ECG, EMG, and EEG. The new Epidermal Sensor Systems created with the Cut-and-Paste manufacturing method perform equal to or better than conventional electrodes. Thus the cut-and-paste method is determined to be a novel and more cost effective method to produce stretchable sensors. Stretchable sensors we produce can match the thickness and mechanical stiffness of human epidermis, and can hence be laminated and fully conformed on human skin like a temporary transfer tattoo for long-term biopotential monitoring including electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG). Such epidermal sensors have enabled the investigation of muscle fatigue and recovery over time. An Autoregressive Moving Average (ARMAX) model is developed in order to map between forearm flexor muscle EMG and the grip force of the corresponding hand. The fit of this model is tracked over the course of fatigue, and changes in the model are analyzed to provide useful trends with which to measure and follow muscle fatigue patters. The epidermal sensor is found to be equivalent to conventional electrodes for muscle fatigue monitoring, while being more comfortable and durable. Further, the ARMAX modeling procedure is proven to have useful results in terms of modeling of forearm muscle fatigue. Overall, this research contributes to the field of stretchable electronics and their applications for biopotential monitoring.