The objective of this research is to develop extremely low-power wake-up receivers. The approach is using novel ultrasonic data-communication devices and electronics. In wireless sensor and tag networks for ambient intelligence, structural and asset monitoring and personal health monitoring, sensing tags employ wake-up receivers to monitor requests for information from the central control node. These always-ON devices need to operate with extremely low power to save battery life or enable operation from energy scavenged from the environment.

The proposed ultrasonic data communication technologies offer two orders of magnitude of power reduction over current radio communication-based solutions. A novel technology platform combining flexible polymer piezoelectrics and integrated circuits will enable miniature ultrasonic transducers. These advances can also enable significant advances in proximity sensing, ranging, and communications through a variety of media with applications in automation, ambient intelligence and medical diagnostics and health monitoring, where radio transmission is poor or interference is not acceptable.

The use of sensor and tagging networks is still in its infancy and the proposed research and education program will offer new technology and human capital to apply these technologies for the benefit of society. The graduate and undergraduate education and outreach activities of this cross-disciplinary program help train the next generation of researchers in ultra-low power electronics, device microfabrication and integration, and sensor networks. Ultrasound communication and localization modules will be developed with the Harlem Robotics League, a community outreach program for public high school students from underrepresented minority groups in Harlem.

Project Report

Project and Outcomes Low cost and ultra low power wireless sensors have a vast array of applications in industrial, structural and environmental monitoring. Several of the potential applications have a significant societal impact; examples include border surveillance, air-pollution monitoring, forest-fire detection, greenhouse monitoring, machine-health monitoring, or wastewater monitoring. This research focused on reducing the energy consumption of wireless sensors by focusing on the wake-up receiver, which is the biggest energy consumer in the node. We demonstrated that the conventionally used radio-frequency (RF) based wireless data communication solution can be replaced with a through-air ultrasound based wireless data communication solution. This resulted in a tenfold reduction of the energy consumption. Conventionally-used RF-based wireless communications for small-form-factor devices like sensors or mobiles use carrier frequencies of hundreds of MHz to several GHz. The associated electronic receivers and transmitters must be designed to handle these high speeds. This results in substantial power dissipation so that regular battery replacements are required, which are both difficult and costly. Ultrasonic communications use low frequency carriers, from a few tens of kilohertz to a few MHz, which enables an order-of-magnitude reduction in the power consumption of the communication electronics. The wavelengths of ultrasound waves in air are small so that still small receive and transducers can be used. The ultrasound transducers are the equivalent of the antennas in an RF system. In this research, we developed a custom-designed ultrasonic-receiver integrated circuit (IC) and built receive and transmit modules to field test the ultrasound data communication system. The IC achieves a ten-fold reduction in power consumption over the state-of-the-art RF-based receivers. The use of ultrasound wake-up receiver thus enables a significant energy consumption in wireless sensor nodes. This can lead to the use of smaller batteries for a given sensor lifetime target or to a substantially longer lifetime when using the same battery, e.g. from a few months to several years for a small coin size battery. In addition, ultrasound communications is not affected by radio interference and does not generate possible harmful RF interference in applications of wireless sensor networks in RF regulated environments like hospitals. Highlights and Achievements: Design of an Ultra-low-power Integrated Circuit (IC) To demonstrate the feasibility of ultra-low-power communication using ultrasonic waves, proof-of-concept transmitter and receiver modules were built and extensively field tested in typical environments like offices, car garage and lecture halls. Team Wins $100K First Prize in the Interdigital Innovation Challenge The "Ultrasonic Wireless Sensors" team, consisting of Ph.D. student Kshitij Yadav, and principal investigators Prof. John Kymissis and Prof. Peter Kinget, won the $100K First Prize in the Interdigital Innovation Challenge. The winners were announced on September 21st 2012 at the GigaOM's Mobilize conference held in San Francisco. The competition drew entries from top universities all across the United States and Canada. "Ultrasound communication" Team Gets Recognition as One of its University’s Promising Start-ups. The team also won the Columbia University’s All-star Competition (Oct’11). This gave exposure of the research work to Columbia’s students and alumni. Our team is regularly invited to be showcased among Columbia’s promising startups in events like ‘Technology You Can Touch’ (Nov’ 12) and ‘Engineering Entrepreneurship Night’ (Dec’12) as well as in University press releases. Team is awarded $150K Small Business Innovation Research (SBIR) Grant by NSF. Our team has been awarded a NSF $150K Phase I Small Business Innovation Research (SBIR) award titled "Ultrasound Data Communications for Wireless Sensors and Real-Time Location Systems". The grant is being used to carry out technology development to further the ultra low power ultrasound data communications towards commercialization. Publications to date "A 4.4-uW Wake-Up Receiver using Ultrasound Data Communications," Digest of technical papers IEEE Symposium on VLSI circuits, pp. 212-213, June 2011. "A 4.4-uW Wake-Up Receiver using Ultrasound Data," to be published, IEEE Journal of Solid-State Circuits, March, 2013.

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Columbia University
New York
United States
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