NASA Space Communications Symposium Biosensor Networks Principal Investigators

NASA Space Communications Symposium Biosensor Networks Principal Investigators: Frank Merat, Wen H. Ko Task Number: NAG 3 -2578 Case Western Reserve University September 18, 2002 1

Biosensor Networks Project Overview The goal of this project is to develop a test platform for biomedical monitoring using COTS components and stateof-the-art communications concepts. Start date March 2001. Biomonitoring Network Body drawing from Fundamentals of Bioelectrical Impedance Analysis, Rudolph J. Liedtke, RJL Systems, February 1998. 2

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. 3

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 4

Biosensor Networks Milestones - Technical Accomplishments and Schedules 1 Due Date Milestone Description Tech Accomplishments 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. 5

Biosensor Networks Milestones - Technical Accomplishments and Schedules 2 Due Date Milestone Description Tech Accomplishments 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 6

Biosensor Networks Milestones - Characterize human body as rf communications channel 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. 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. 7

Biosensor Networks Milestones - Technical Accomplishments and Schedules 3 4 Due Date Milestone Description Tech Accomplishments 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 Due Date Milestone Description Tech Accomplishments August 2002 Develop software to transmit data and network nodes. Completed development and testing of prototype system. Schedule Status Schedule Deviation Completed none 8

Biosensor Networks Prototype sensor node Bare PC board for prototype Typical rectangular center fed patch antenna used for testing. “early” power for prototype Antenna board for prototype Prototype sensor node with integrated antenna and Dsocket for programming 9

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

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

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. 12

Biosensor Networks Propagation modeling Transmission Line Model of Antenna/Human Circuit using experimentally measured antenna parameters and published values for the electrical parameters of the human body Simulation of Transmission Line Model for 0. 6 Meters Antenna Separation 13

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). 14