Recent advances in embedded computing systems have led to the emergence of wireless sensor networks, consisting of small, battery-powered "motes" with limited computation and radio communication capabilities. Sensor networks permit data gathering and computation to be deeply embedded in the physical environment. This technology has the potential to impact the delivery and study of resuscitative care by allowing vital signs to be automatically collected and fully integrated into the patient care record and used for real-time triage, correlation with hospital records, and long-term observation.
This project is supported by grants from the National Science Foundation, National Institutes of Health, U.S. Army, as well as generous gifts from Sun Microsystems, Microsoft Corporation, Intel Corporation, Siemens AG, and ArsLogica.
AID-N and CodeBlue featured on CNN, March 14, 2007 (the story does not mention CodeBlue and Harvard, although the CodeBlue software runs the devices).
We have developed a range of wireless medical sensors based on the popular TinyOS "mote" hardware platforms. A wireless pulse oximeter and wireless two-lead EKG were among the first two sensors developed by our lab. These devices collect heart rate (HR), oxygen saturation (SpO2), and EKG data and relay it over a short-range (100m) wireless network to any number of receiving devices, including PDAs, laptops, or ambulance-based terminals. The data can be displayed in real time and integrated into the developing pre-hospital patient care record. The sensor devices themselves can be programmed to process the vital sign data, for example, to raise an alert condition when vital signs fall outside of normal parameters. Any adverse change in patient status can then be signaled to a nearby EMT or paramedic. These vital sign sensors consist of a low-power microcontroller (Atmel Atmega128L or TI MSP430) and low-power digital spread-spectrum radio (Chipcon CC2420, compliant with IEEE 802.15.4, 2.4 GHz, approximate range 100 meters, data rate about 80 Kbps). The devices have a small amount of memory (4-10 KB) and can be programmed (using the TinyOS operating system) to sample, transmit, filter, or process vital sign data. These devices are powered by 2 AA batteries with a lifetime of up to several months if programmed appropriately. The basic hardware is based on the MicaZ and Telos sensor nodes, described above, and a custom sensor board integrating the pulse oximeter or EKG circuitry is attached to the mote devices.
|Wireless pulse oximeter sensor.||Wireless two-lead EKG.||Accelerometer, gyroscope, and electromyogram (EMG) sensor for stroke patient monitoring.|
CodeBlue is also being used by the AID-N project at Johns Hopkins Applied Physics Laboratory, which is investigating a range of technologies for disaster response. The AID-N wireless sensors (which run the CodeBlue software) include an electronic "triage tag" with pulse oximeter, LCD display, and LEDs indicating patient status; a packaged version of our two-led EKG mote, and a wireless blood pressure cuff. The ETag sensor hardware was developed by Leo Selavo at University of Virginia.
|UVa/AID-N "eTag" wireless triage tags, with pulse oximeter, LEDs to indicate patient triage status, and control buttons.||UVa/AID-N wireless two-lead EKG (same as above, but with case).||UVa/AID-N wireless blood pressure cuff.|
In collaboration with the Motion Analysis Laboratory at the Spaulding Rehabilitation Hospital, we are developing developing the Mercury system, which is designed to support high-resolution motion studies of patients being treated for neuromotor conditions such as Parkinson's Disease, stroke, and epilepsy. See the Mercury project page for more details.
Our sensor hardware designs are available under an "open source" license to research groups that are interested in experimenting with these devices. We are actively pursuing research collaborations with other medical groups, disaster response teams, and companies interested in this technology. Please contact us for more information.
|CodeBlue architecture for emergency response.|
In addition to the hardware platform, we are developing a scalable software infrastructure for wireless medical devices, called CodeBlue. CodeBlue is designed to provide routing, naming, discovery, and security for wireless medical sensors, PDAs, PCs, and other devices that may be used to monitor and treat patients in a range of medical settings. CodeBlue is designed to scale across a wide range of network densities, ranging from sparse clinic and hospital deployments to very dense, ad hoc deployments at a mass casualty site. CodeBlue must also operate on a range of wireless devices, from resource-constrained motes to more powerful PDA and PC-class systems. For more information, please see the IEEE Pervasive Computing article about CodeBlue or this technical report with more details.
Part of the CodeBlue system includes MoteTrack, a system for tracking the location of individual patient devices indoors and outdoors, using radio signal information. In MoteTrack, a hospital, clinic, or other area is outfitted with a set of fixed radio beacon nodes that are used to calculate the 3D position of the wireless sensors, which may be attached to patients, carried by physicians or nurses, or attached as "location tags" to medical equipment. MoteTrack has been demonstrated in a building-wide deployment at Harvard and yields an 80th percentile error of about 2 meters, which is more than adequate for many location-tracking applications.
The CodeBlue system is currently under development and we anticipate a source code release soon. The MoteTrack system is currently available for download at the link above.
Our research focuses on the following areas:
We are also investigating wide-area event delivery infrastructures for medical care, as part of the Harvard Hourglass project. Such a system will allow seamless access to patient care data by EMTs, emergency department personnel, and other physicians through a variety of interfaces, including handheld PDA and Web-based clients. In collaboration with 10Blade, we are integrating Vital Dust sensors into iRevive, a PDA-based patient care record database. The combined system will allow real-time vital sign capture and triage, automatically inserting time-stamped vital sign data in the patient care record (PCR) prepared by EMTs. This will lead to more accurate reporting and a significant reduction of paperwork for EMSs. Our PDA-based triage application displays vital signs for multiple patients and immediately alerts the EMT to a change in patient status.
You can download a prototype release of the CodeBlue software and hardware description files here:
We have also created a public mailing list for users of the CodeBlue software. Use this list for questions, comments, and discussion about the system as well as to receive notification of updates. To subscribe, visit this page: