A user device 100 comprises a substrate 102, e.g. touchscreen display, with one or more electrodes 101 overlaid thereon. Each electrode 101 connects to an amplifier 108 for detecting an electrocardiogram (ECG) signal when touched. Preferably, electrodes 101 are transparent, e.g. Indium Tin Oxide (InSnO； ITO). Electrodes 101 may electrically interface with substrate 102. The set of electrodes may comprise parallel horizontal electrodes on top of orthogonal parallel vertical electrodes, both layers separated from each other by transparent insulating strips. A transparent printed circuit may be fabricated on the substrate to amplify and filter signals. The electrodes may also be provided on e.g. a steering wheel or a door handle. A method of use comprises displaying instructions to a user to touch a transparent dry set of electrodes 101 on a substrate 102 to obtain an ECG measurement. Instructions may comprise holding the touch for a period of time.
