Smart Mattress
Bryan Kuo, Priyen Patel, Dev Shah, Xitij Shah, Tim StammGeorgia Institute of Technology
December 5, 2008
Project Overview
Goals: Prevent bedsores acquired on hospital/nursing home beds
Wetness DetectionInactivity Detection
Prevent incorrect medication administrationPatient Identification SystemPatient Barcode Display
Clients: Hospitals Nursing Homes
Cost: $1,055
Design Objectives
Identify patients using RFIDDisplay patient information and barcode
on a PC monitorDetect moisture and patient inactivity that
could cause bed soresAlert staff if patient is in danger of
developing bed sores
Overall System - Current
Overall System - Current
Previous RFID System
Passive RFID System OBID i-scan HF RFID Reader OBID i-scan HF Pad AntennaRFID Operating Frequency: 13.56 MHzRFID Antenna Range: 7 in. RFID Transmitting Power: 1W ± 2 dB
* Note: This range did not meet our specifications
Current RFID System
Active RFID SystemWavetrend RX201 Active RFID ReaderWavetrend AN100 Active Whip AntennaRFID Operating Frequency: 433 MhzRFID Antenna Range: 35 ftRFID Wavelength: 2.3 ftTag Battery Life: 5 years
RFID System
RFID antenna located at foot of bedWavetrend Active RFID tagsPatient tag compared to patient ID databasePatient name and barcode displayed on PC
RFID Tag Reader and Antenna HP Slimline PC
RFID Detection Range
Inactivity Monitoring System
Inactivity Monitoring System
Wetness Detection
2 conductive loops of tape connected to wetness detection circuit
1st comparator input monitors moisture
2nd comparator detects breaks in the conductive loop
Wetness Detection System
Phidget 8/8/8 Interface Kit
Interface between inactivity monitoring and wetness detection systems with HP Slimline PC
4 analog inputs for FSR strips 1 analog input for sampling wetness
detection circuit output
Current Status
Wetness detection system 2 conductive loops, comparator, and 2 9V batteries Successfully implemented and tested on breadboard
Inactivity monitoring system 4 Trossen Robotics force sensing resistor strips Controlled through Phidget 8/8/8 interface kit Successfully implemented and tested
RFID System Wavetrend Active RFID Reader/Antenna Successfully implemented and tested
Design Specifications
Same1.5 to 150 psiPressure Sensor Range
Same0 to 1000 lbsForce Sensitivity Range
Trossen Robotics 24” FSR
Same16 msSwitching Loop-time
< 5mACurrent Consumption
2 9V batteries 3.3 VPower Supply
Phidget 8/8/8 Interface KitPIC18 LF2321Microprocessor
Multiplexer
Max. 0.5 ARFID Current Draw
35 ft.1 ft (12 in.)Max RFID Reading Distance
N/A1W ± 2 dBRFID Transmitting Power
433 MHz13.56 MHzRFID Operating Frequency
RFID Reader
ActualProposedTechnical Specifications
Competing Products
Total Care SpO2RT Hospital Bed Secure II Med/Surg Hospital Bed
$28,500 $10,000
Cost
$250$2501HP Slimline PC
$1,055 Total Equipment Cost
$50 $50 1PC Monitor
$30$30 1Bed Sheet
$150 $150 1Mattress Foam
$50 $50 75ftConductive Tape
$307 $307 1RFID Tag and Reader
$15 $7.50 29V Battery
$15 $15 1Wires/Cables
$80 $80 1Phidget 8/8/8
$108 $27 4FSR Robotics Sensor Kit
Total CostUnit CostQuantityPart
Selling Points
Lower cost Costs $1,055 Competitor products cost at least $10,000
Portable More versatile
Combines wetness and inactivity detection Utilizes RFID to prevent improper
medication administration Appealing Graphical User Display
Future Considerations
Use a smaller, cheaper microcontroller such as a PIC
Implement systems on a PCB Find smaller wrist/ankle band active
RFID tags
PIC Microcontroller
Used for integrating wetness detection, inactivity monitoring, and patient identification systems into a low-cost power-efficient package
Low power operation using 3V coin cell battery
Programmed in C via 6-pin header through PICkit2
RS232 communication to PC using onboard UART
Pushbutton and LED for debugging
PIC for Inexpensive System Integration
RFID Implement either using RS232 with current
reader or SPI enabled readerInactivity monitoring
Sample force sensing resistors using onboard ADC
Wetness detection Sample output of comparators using digital
inputLCD for display of system status
Demonstration Plan
Inactivity Detection Group member lays for extended period of time. LCD monitor displays inactivity alarm
Patient Identification RFID tag located within antenna range LCD monitor displays patient name LCD monitor displays patient medication barcode
Wetness Detection Salt water poured on bed LCD monitor displays wetness alarm