The design and implementation of a microcontroller based platform compatible with IEEE 1451.4 standard for high performance unobtrusive accurate cardio-respiratory and motor activity estimation of wheelchair users are presented in this paper. The platform is a multi-sensor architecture that includes sensors with plug-and-play and auto-identification capabilities, a RFID reader that is used to identify the wheelchair user, and RFID tags mounted in critical regions of the indoor habitat. The acquired data from the smart sensor channels are delivered through Bluetooth communication or wired serial communication to a host computer that includes a server application associated with IEEE 1451.4 TEDS management and display of the measured data. Elements of human-machine-interface (HMI) implementation and several experimental results are included in the paper.