Page 1 Biosensor Networks Principal Investigators: Frank Merat, Wen H. Ko Task Number: NAG3-2578 Case Western Reserve University September 18, 2002 NASA Space Communications Symposium
Page 1
Biosensor Networks
Principal Investigators: Frank Merat, Wen H. KoTask Number: NAG3-2578
Case Western Reserve UniversitySeptember 18, 2002
NASA SpaceCommunications Symposium
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Biosensor Networks
Project Overview
The goal of this project is to develop a test platform for biomedical monitoring using COTS components and state-of-the-art communications concepts. Start date March 2001.
Body drawing from Fundamentals of Bioelectrical Impedance Analysis, Rudolph J. Liedtke, RJL Systems, February 1998.
RF SourceSpectrum Analyzer
Biomonitoring NetworkComputer Medical
Data Logger/Analysis Station
Conventional RF Link (BlueTooth?)
IntraBody Wireless Network
IntraBody/Extrabody Wireless Network
Router
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Biosensor Networks
Enterprise Relevance
This technology has applications for continuous health monitoring of humans in space and for long duration space experiments involving humans and/or animals.Any wireless solution should interface with existing and future proximity networks.
“A Lightweight Ambulatory Physiological Monitoring System,” NASA Tech Briefs, January 2001.
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Biosensor Networks
Enterprise Impact
The major impact of this technology is upon manned missions, e.g., space station and shuttle missions .
Removal of wires and other encumbrances would improve astronaut freedom of movement and increase the system reliability.
Wireless Biosensor Network
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Biosensor Networks
Milestones - Technical Accomplishments and Schedules
Due Date Milestone Description Tech Accomplishments
1 April 2002 Characterize human body as communications channel for rf.
Communications through human body.
Schedule Status Schedule Deviation
Completed none
Feasibility Experiment
Body drawing from Fundamentals of Bioelectrical Impedance Analysis, Rudolph J. Liedtke, RJL Systems, February 1998.
RF SourceSpectrum Analyzer
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Biosensor Networks
Milestones - Technical Accomplishments and Schedules
Due Date Milestone Description Tech Accomplishments
2 June 2002 Design antennas for coupling to human body.
Designed and measured multiple patch antennas. Verified antenna performance with loop antennas and published literature.
Schedule Status Schedule Deviation
Completed none
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Biosensor Networks
Milestones - Characterize human body as rf communications channel
Received Power Through the Body (underside of forearm with 30 cm separation). Antenna dimensions: L =39 mm, W = 42
mm, and h = 0.062” on FR-4 substrate.
Received Power at 50 cm separation.Transmitter antenna: L = 54 mm, W = 48 mm, h = 0.062”; receiver antenna L = 26
mm, W = 38 mm, h = 0.062”, both on FR-4 substrate.
Geometry of Basic Rectangular Patch Antenna
Received Power at 1 m separation. Antenna dimensions are L = 41 mm, W = 38 mm, and h = 0.062” on FR-4 substrate.
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Biosensor Networks
Milestones - Technical Accomplishments and Schedules
Due Date Milestone Description Tech Accomplishments
4 August 2002 Develop software to transmit data and network nodes.
Completed development and testing of prototype system.
Schedule Status Schedule Deviation
Completed none
Due Date Milestone Description Tech Accomplishments
3 August 2002 Design prototype wireless nodes for collecting and transmitting sensor data through human body.
Completed fabrication and testing of prototype nodes.
Schedule Status Schedule Deviation
Completed none
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Biosensor Networks
Prototype sensor node
Typical rectangular center fed patch antenna used for testing.
Bare PC board for prototype
Prototype sensor node with integrated antenna and D-socket for programming
“early” power for prototype
Antenna board for prototype
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Biosensor Networks
Risks
Risk Impact Resolution Plan
1 EMI from radiated signals not confined to human body.
Would restrict application of technology, especially in space missions.
Reduce transmitter power.
2 Antenna size is too large.
Would restrict application of technology
Shift to higher operating frequency
3 Wireless nodes consume too much power.
Increases size of wireless modules.
Redesign electronics using newer COTS technology or semi-custom design.
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Biosensor Networks
Funding Issues
Phase one funding ended on budget.Phase two funding through March 2003.
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Biosensor Networks
Future Plans
Event Goals
1 Biomedical sensor survey Determine COTS biomedical sensors suitable for a personal biosensor network.
2 Antenna testing Optimize antenna dimensions for biosensor network. Impedance match antenna to electronics.
3 Functional prototype Demonstration prototype.
4 Modeling of rf propagation in human body.
Conventional radiation and transmission line models do not explain observed behavior. A better model (perhaps including ionic conduction) would allow better prediction of system performance and optimization of antenna.
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Biosensor Networks
Propagation modeling
Simulation of Transmission Line Model for 0.6 Meters Antenna Separation
Transmission Line Model of Antenna/Human Circuit using experimentally measured antenna parameters and
published values for the electrical parameters of the human body
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Biosensor Networks
Papers and Awards
[1] M. Dummeruth. Wireless Wearable Health Monitoring System. M.S. Thesis, Case Western Reserve University, August 2002. (Advisor: F. Merat).