Embodiments of the present disclosure provide techniques and configurations for a signal transmission for an apparatus, such as a mobile or wearable device, based on sensor fail-safety. In one instance, the apparatus may comprise a transmitter to transmit a communication signal of the apparatus at a first power level, a sensor to monitor a process that is external to the apparatus and to provide an output signal indicating a change in a state of the process, and a control module communicatively coupled with the sensor and transmitter, to determine whether the output signal provided by the sensor has indicated a change in the external process over a threshold time period, and, based on a result of this determination, cause the transmitter to switch the transmission from the first power level to a second power level that is lower than the first power level. Other embodiments may be described and/or claimed.