  In this article we propose the use of accelerometer embedded by default in
smartphone as a cost-effective, reliable and efficient way to provide remote
physical activity monitoring for the elderly and people requiring healthcare
service. Mobile phones are regularly carried by users during their day-to-day
work routine, physical movement information can be captured by the mobile phone
accelerometer, processed and sent to a remote server for monitoring. The
acceleration pattern can deliver information related to the pattern of physical
activities the user is engaged in. We further show how this technique can be
extended to provide implicit real-time security by analysing unexpected
movements captured by the phone accelerometer, and automatically locking the
phone in such situation to prevent unauthorised access. This technique is also
shown to provide implicit continuous user authentication, by capturing regular
user movements such as walking, and requesting for re-authentication whenever
it detects a non-regular movement.
