Nanomaterial epidermal sensors can be adhered to the skin and worn comfortably and inconspicuously for days to allow for repeated biometric sensing. The nanomaterial epidermal sensors may be comprised of a monolayer of graphene coating a flexible polymer substrate. Various nanomaterial epidermal sensors may be quickly fabricated using a cost-efficient “cut-and-paste” method on transfer paper and can be adhered directly to skin without tape or adhesive, much like a temporary-tattoo. The nanomaterial epidermal sensors may be optically transparent and may be used to measure an electrocardiogram (ECG), an electroencephalogram (EEG) or an electromyogram (EMG) with a signal-to-noise ratio that is comparable to conventional electrodes. In addition, the nanomaterial epidermal sensors may be used to measure other parameters, such as skin temperature or skin hydration.
