Power Matters ULP Wireless Technology for Biosensors and Energy Harvesting Reghu Rajan September, 2012
Presentation Overview Overview of wireless telemetry and sensors in healthcare Radio requirements for sensors in wireless healthcare Applications & energy harvesting Conclusion
Key Areas in Medical Telemetry Implanted Medical Telemetry Communication with implanted medical devices External Medical Telemetry Communication with patient sensors located near or on the skin Sensors/instrument Bedside monitor Remote station Network classifications (a) Body or Personal Area Network (BAN or PAN) Transmission into or around body (b) Human Area Network (HAN) Transmission using body
Typical Applications And Improvements to Patient s Quality of Life Operating Room Home Monitoring Doctor s Office
Applications with Sensing and Therapies Enable new wireless applications and therapies to improve patient care and lower healthcare costs Improving quality-of-life for an aging population Increasingly mobile, independent population driving demand for home-based healthcare Pain or symptom management for range of diseases Enabling new, breakthrough treatments Reducing healthcare costs Preventative diagnostics Shorten surgery time, eliminate some surgical procedures Functional stimulation Defibrillator Cardiac pacemaker/ Energy harvesting Drug delivery/ Insulin pump Hearing assistance Deep brain stimulation/ Neurostimulator Wireless endoscopy Bladder control
Moving the Cycle of Care from Hospital to Home Wireless Monitoring is a Key Element of the Transition Involves implant and non-implant radio Technology used by healthcare facilities To lower costs To improve patient outcomes Healthcare delivered outside formal institutions Aging world population Need for better management of chronic diseases Explosive growth predicted for developing countries Enabled by remote healthcare
External Sensing- Use Cases and Technology Ultra Low Power QoS Medical Quality Reliable Secure
External Sensing- Continuous Monitoring Sensors Energy Harvesting Body heat energy harvesting (Seebeck effect based) Motion energy harvesting Disposable sensors Temperature plaster Ovulation detection etc. Common key requirement: Low power for long battery life Low peak current due to high impedance power source
Radio Requirements for Ultra Lowpower Wireless Sensors
Key Considerations for Radios in Wireless Sensors Link Frequency Antenna Impedance Network protocol Footprint Peak & Average current Streaming Capability & data rate Supply Voltage ULP Radio Wake-up feature
Key Features for Radios in Wireless Sensors Supply Voltage Sub 2 Volts operation For single cell applications (sometime down to 1V) Different battery chemistries Maintain TX and RX performance PA and matching network design Power supply rejection Current profile without excessive peaks to fit supply impedance
Key Features for Radios in Wireless Sensors Peak and Average Current Low peak current While average low power can be achieved by extreme duty-cycling, this may not work with energy sources that have higher impedance such as thin-film, zinc-air batteries and energy harvesting transducers etc. Good power-supply rejection Efficient sniff or wakeup features For non streaming application that require waking up of radio, sniffing can be a significant source of average power consumption TZ1030/53 Toumaz CC11/24xx Texas Instruments ZW0301 Sigma Designs EnOcean 868MHz modules ZL70250 Microsemi ULP RFIC
Key Features for Radios in Wireless Sensors Link frequency Application dependent frequency and choice of radio The band frequency can affect the link quality and power consumption for medical telemetry. The MICS band, 402-405MHz, is ideal for implant telemetry due to low tissue absorption. For non-implant applications ISM band at 900MHz and 2.4GHz are available, but for lower path loss, less directivity and lower power consumption 900MHz maybe better suitable than 2.4GHz. Free-space path-loss is 8.7dB higher for 2.4GHz compared to 900MHz High data-rate may require 2.4GHz at the cost of power
Key Features for Radios in Wireless Sensors Antenna Impedance Non-standard antenna impedance is becoming more common due to specialized antenna size requirements and low supply voltage. Careful planning of TX/RX circuits and antenna can minimize requirement on matching network and hence the insertion loss between the radio and the antenna and cost. Non-standard impedance helps more efficient PA design for given supply voltage
Key Features for Radios in Wireless Sensors Network Protocol Several standards are currently available for network protocol such BLE, Ant, Zigbee etc. Medical data varies from a applications that requires few bytes/s to few Mbps Most of standard protocols have huge over heads that decrease the payload efficiency for small data rates and packet sizes Therefore one size fits all strategy does not work for optimum power consumption in medical telemetry!
Key Features for Radios in Wireless Sensors Wake-up feature Efficient wake-up strategies can be crucial for low average power consumption, especially for implant radios and low-power sensors. Multi-stage wake-up scheme with smart Rx correlation for progressive waking up of stages to save power from false wake-ups.
Applications and Energy Harvesting
Wireless Sensing and Radio Technology Trends Reliability Possible Future Trends as IEEE 802.15.6 emerges Faster Growth as cost lowers for 802.15.6 & 15.4 Limited into implant market Relative Market Share IEEE 802.15.6 & 15.4 Low Power Bluetooth Custom Reliability Low Medium High High Wireless Cost Low Low Medium High Environment Consumer, home, rehabilitation Aged Care, General Hospital Examples Fitness Monitor Temperature, Weight Operating Room, Intensive Care ECG, Blood Oximeter Implant Implant Devices Energy Harvesting applications
Growth Area: Neuro-sensing and Modulation Source St Jude Annual Report 2009
Example: Remote Sensing and Pacing ZL70102 Integrated Circuit Transceiver designed for base stations and Implanted Medical Device (IMD) RF Modules Fully tested, implantable RF modules Reference Designs IMD and base station Design Tools Software, documentation, app notes Evaluation kits
Growth are: Baroreflex Activation Therapy for Blood Pressure Startup CVRx Minneapolis (largest VC financing in state) Electrically activates the carotid baroreceptors, the body s natural cardiovascular regulation sensors Brain senses stimulation and regulates both sympathetic and parasympathetic activity in the heart, blood vessels and kidneys These changes result in maintained or improved cardiac output at a reduced blood pressure thereby reducing the load on the arteries and heart. Mircosemi wireless transceiver used for communication in the Barostim neo system
Example: Wireless Camera Capsule- Given Imaging Size: 11 x 26 mm Weight: < 4 gram View angle: 140 o at each end Healthy Small Bowel
Example: Wireless Camera Capsule- Given Imaging World s First Swallowable Wireless Camera Capsule, from Given Imaging, including Microsemi s ULP RF Transmitter Microsemi s RF IC Approximately 57,000 pictures transmitted over 8 hours Second generation incorporates technology to define pill location
Example: Wireless Hearing Aid- Remote Sound Sensing Continuous wireless stereo audio steaming to hearing aids: Uses Microsemi s ULP ISM RF Transceiver Microsemi s ISM RF IC
Energy Harvesting based Wireless sensor Block diagram of typical EH based sensor
Energy Harvesting based Wireless sensor Practical sensor based on ZL70250 ULP radio and Perpetua Thermo-Electric Generator
Power Matters Thank You