Projects:2014S1-38 Semi-Passive Wearable Sensors
Contents
Project Introduction
Motivation
Older people may have the risk of falling when they move from one position to another. People tend to stay away from video monitoring because studies have shown that people do not like to be videoed and images are seen as an invasion of privacy, especially with older people.
Motivation of this project is to provide smart living spaces of tomorrow for older people through non-invasive activity monitoring using wearable sensors and environmental sensors.
Aim and goals
Our aim is to prototype a new generation of battery-less sensors for monitoring human motion. We build our prototype based on the WISP4.1 DL version.
Our design goals are:
To develop our WISP tag with accelerometer and barometer.
To test the performance of the WISP tag.
To implement RFID communication between reader and WISP tag.
Introduction
The WISP is a passive Computational RFID that harvests operating energy from, and communicates with, UHF RFID readers. It can also process data from its onboard sensors. We developed the new WISP which has extended functionality with its advanced accelerometer and barometer, SPI and I2C bus, and copper wire antenna.
The new WISP provides a RFID-scale, fully programmable, battery-less sensing platform that executes programs on its MSP430 microcontroller. The hardware and software are both derived from the open source WISP 4.1DL wiki.
Figure 1. System Structure
Hardware Development
Analog Front End
·Dipole antenna
·Schottky diode HSMS-285x
·5 voltage-doubling stages
·M4 modulation, backscatter
·70 Ω impedance matching, 915MHz
Figure 2. Analog Front End
Digital section
·Supervisory circuitry for waking up WISP tag
·Voltage level translator
·Microcontroller (MSP430F2132) 
··Ultra-low power consumption
··Standby Mode: 0.7uA
··SPI and I2C peripherals
··Small size, flash RAM
Sotware Development
Group Members
Heranudin
Qiushi Li
Zhigeng Qian
Supervisor
Said Al-Sarawi
Damith Ranasinghe
