A sensor apparatus 100 for an item of smart clothing houses sensor electronics comprising at least one position and/or orientation sensor 105, and a data store 107, coupled to a processor 103 and powered by a battery 101. The processor 103 is configured to receive signals indicative of a change in position and/or orientation from the position and/or orientation sensor 105. The processor 103 is also configured to determine from the received signals whether there has been a change in position and/or orientation of the sensor apparatus over a first selected time interval； and in the event that there has been a change in position and/or orientation of the sensor apparatus over the first selected time interval, the processor 103 is configured to record the change in position and/or orientation to the data store 107. The apparatus 100 may include a wireless communications interface 109 and if it determines the wireless communications interface 109 is coupled to a remote device 600, it may upload data to the remote device 600. A temperature or humidity sensor may be included and an alert may be sent if the sensed temperature or humidity are above a threshold. The apparatus 100 may have a one way valve 156 to allow pressure to be released. Sensors for smart clothing may communicate with each other to share information and determine correct orientation.
