School of Engineering and Digital Arts Creative Use of RFID (Radio Frequency Identification) John Batchelor
Contents What is RFID? RFID Tattoos Conducting Ink Passive sensing for healthcare and other applications Future work Page 2
Applications of RFID and Pervasive Sensing Stock control Transport Anti-theft Healthcare Assisted Living Anti-counterfeiting Page 3
What is RFID? (UHF type) Works like RADAR Energy comes from reader antenna Tag takes energy from received signal and reflects information back to reader No battery needed at the tag (Passive System) Tag switch Reader antenna These tags can only be detected when they are near to a reader. Page 4
RFID can be worn or body mounted for use in: Healthcare Airports Power Plants Military Bases and depots Refineries Oil Rigs Concerts/entertainment events Page 5
Tags and Wrist bands can be given to other people Swapping tags can be avoided by injecting them below the skin as capsules: Or as tattoos: However, neither is suitable for temporary or short term tagging. Page 6
At Kent we created the world s first temporary transfer tattoo RFID tag: Page 7
Making Tattoo Tattoos Conducting Nickel compound or silver paint Volunteer s arm Protected by polymer spray bandage Etched metal stencil Prototypes were also created on inkjet tattoo transfer paper by colleagues at Manchester: Chip attachment by tape Page 8
Read range (m) Measurements Measurements of read range (since improved to best case of 2.2m) 1.40 1.20 1.00 0.80 0.60 0.40 0.20 Read range 0.00 867 910 918 924 954 Frequency (MHz) simulated read range measured read range on chest measure read rangeon arm measured read range on stomack Page 9
Sticking Plaster Tags Tags can also be made on conducting fabric and integrated into sticking plaster. Read ranges would be improved with fabrication however for medical applications short range is preferable. Page 10
Resonant frequency MHz The tattoo performance is affected by its dimensions Resonant frequency variation for changes in antenna parameters 1200 1100 Tag operating frequency is mostly affected by slot dimensions. 1000 900 800 700 600 SL SW D L D 500 0 2 4 6 8 10 12 14 16 18 20 Variation in antenna parameter mm SW L SL This means tag could detect stretch or strain Page 11
An RFID Strain Gauge Strain y 1% 2% 3% 4% 5% x Z A R C [Ψ] Z C When mounted on the skin, movement can be detected. Alternatively, expansion joints can be monitored, or the structure health of buildings. Page 12
An RFID Strain Gauge The important thing here is to obtain a conductor that can stretch without breaking. Printed inks will suffer micro-cracking which limits the current and stops the tag working. Stretchable fabric based conductors are being used for initial prototyping. Page 13
Reduced Size Mouth Mounted RFID Switch Design Measurements with mouth open: Tongue-tag separation (mm) 900MHz Transmitted Power (dbm) State 30 22 On 20 23.5 Proximity sense 15 24 Proximity sense 10 26.5 Proximity sense 6 27 Proximity sense 4 No Read Off 2 No Read Off 0 No Read Off 5dB range for proximity sensing and a clear distinction between on and off (read/no read). Page 14
An RFID Switch to control wheelchairs The tag was also tested to work on the tongue: Inside the mouth With the mouth closed This work is supporting the European SYSIASS project at Kent, Essex and Lille Universities together with NHS and French hospitals. Page 15
An RFID Chemical Sensing RFID Chemical Sensing Working with Polymer Scientists at Kent to create tag substrates that are sensitive to chemicals. This could lead to many applications such as packaging capable of detecting the state of food, tattoos that smell explosives, or medical patches that can detect sweat. Our current research is with Inkjet specialists at Manchester in order to digitally print these devices as labels. Page 16
Conclusion RFID tags can be placed directly onto skin in the form of transfer tattoos. Inkjet conducting ink to make this a cheap and widespread technology. Future tags could sense stretch, temperature, humidity, gas and touch. Wireless devices could be connected without needing batteries. Security will need to be developed if sensitive data is transmitted. Page 17