1. 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

2. Page 2 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. Biomonitoring Network

3. Page 3 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.

4. Page 4 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

5. Page 5 Biosensor Networks Milestones - Technical Accomplishments and Schedules Due DateMilestone DescriptionTech Accomplishments 1April 2002Characterize human body as communications channel for rf. Communications through human body. Schedule StatusSchedule Deviation Completednone Feasibility Experiment Body drawing from Fundamentals of Bioelectrical Impedance Analysis, Rudolph J. Liedtke, RJL Systems, February 1998.

6. Page 6 Biosensor Networks Milestones - Technical Accomplishments and Schedules Due DateMilestone DescriptionTech Accomplishments 2June 2002Design antennas for coupling to human body. Designed and measured multiple patch antennas. Verified antenna performance with loop antennas and published literature. Schedule StatusSchedule Deviation Completednone

7. Page 7 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.

8. Page 8 Biosensor Networks Milestones - Technical Accomplishments and Schedules Due DateMilestone DescriptionTech Accomplishments 4August 2002Develop software to transmit data and network nodes. Completed development and testing of prototype system. Schedule StatusSchedule Deviation Completed none Due DateMilestone DescriptionTech Accomplishments 3August 2002Design prototype wireless nodes for collecting and transmitting sensor data through human body. Completed fabrication and testing of prototype nodes. Schedule StatusSchedule Deviation Completednone

9. Page 9 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

10. Page 10 Biosensor Networks Risks RiskImpactResolution Plan 1EMI from radiated signals not confined to human body. Would restrict application of technology, especially in space missions. Reduce transmitter power. 2Antenna size is too large. Would restrict application of technology Shift to higher operating frequency 3Wireless nodes consume too much power. Increases size of wireless modules. Redesign electronics using newer COTS technology or semi-custom design.

11. Page 11 Biosensor Networks Funding Issues Phase one funding ended on budget. Phase two funding through March 2003.

12. Page 12 Biosensor Networks Future Plans EventGoals 1Biomedical sensor surveyDetermine COTS biomedical sensors suitable for a personal biosensor network. 2Antenna testingOptimize antenna dimensions for biosensor network. Impedance match antenna to electronics. 3Functional prototypeDemonstration prototype. 4Modeling 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.

13. Page 13 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

14. Page 14 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).