Noninvasive Real-Time Optical Sensors For Measuring Vital Physiological Parameters (Mendelson)

Description of the Research

My principal research interest is in the development of innovative noninvasive optical biosensors and instrumentation for real-time physiological monitoring. Our laboratory projects range in scope from basic research to commercial applications. The work involves design and testing of prototype low-cost devices that can aid the health care provider and improve patient care. Most projects involved the design and development of the biomedical sensor, signal conditioning electronics, signal processing software, user interfaces as well as conducting laboratory testing of medical devices.

Photomedical technologies, and particularly optical means to diagnose and accurately monitor vital physiological status, represent a growing area of potential interest mainly because they provide a safe, simple, fast and real-time assessment of different medical conditions. Simple and cost effective diagnostic methods utilizing novel physiological sensors, which would provide clinicians with continuous and reliable real-time information in critical medical situations, are required in order to monitor vital signs and determine the extent of injury in various situations.

For almost 20 years, our laboratory has been actively exploring the applications of photoplethysmography in the development of different prototype wristwatch-size optical sensors for monitoring blood oxygenation based upon the principle of reflectance pulse oximetry. Pulse oximetry is often considered the fifth vital sign, after heart rate, blood pressure, temperature, and respiratory rate. It has served as an important tool for the clinician by providing continuous monitoring of the patient's arterial oxygen saturation (SpO2). Monitoring via pulse oximetry is particularly useful when a patient is unstable and subject to rapid desaturation. The device can alert clinicians to the patient's deteriorating status in time to intervene.

The introduction of powerful microprocessors in the consumer market, and the proliferation of wireless technology and cell phones, is driving down the price of these technologies. During the next couple of years, manufacturers will likely leverage microprocessor technologies, wireless communication and cell phone technology to advance technical developments in wearable medical technologies including pulse oximetry. The application of these technologies is presently being expanded in our laboratory into several new application areas with a common objective to design and develop low-cost, low-power biosensors, wireless communication and easy-to-use wearable devices that can aid in a remote interactive examination. Several applications are provided below:

Home TeleHealth Care

The application of advanced telecommunications technology to long-term home care of the elderly is a rapidly growing segment of the health care industry. The current trend in long-term care is a shift of the delivery system away from institutional care towards home and community-based care. The health care and particularly home care industry is seeking to reduce some of the inefficiencies of home health care by replacing nursing visits with remote collection of vital signs data. By using state-of-the-art two-way medical monitors, health care providers who might be located miles from a patient's home can conduct a checkup on a home care patient's vital signs such pulse rates, blood oxygenation and body temperature. This type of technology could be used round-the-clock with patients who have a variety of long-term medical needs and diseases, including patients with congestive heart failure, chronic cyanotic pulmonary diseases, chronic wound care, permanent disability and terminal illnesses.

Military Applications

Some of the research in our laboratory is focused on efforts to develop technologies to monitor the physiological status of warfighters during military operations and training. The goal of this effort is to provide future operational field commanders with important information regarding the current and predicted physiological state of their soldiers in order to guarantee their warfighters are operating at peak performance. Armed with this type of information, commanders will be much better equipped to assess risk to their forces, plan operations, and tailor logistic support for rations and water. It is envisioned that the next generation combat uniform will ultimately consist of a configurable array of miniaturized, wireless physiological sensors distributed around the warfighter's body. Bi-directional sensor communication will allow sensor function to be reprogrammed on command or as the result of a specific event. For example, a pulse oximeter sensor that that contain an embedded microprocessor would be able to provide a signal to medics in the event of wounding on the battlefield.

Physiological Monitoring in Extreme Environments

Another aspect of my research interest is directed towards remote on-line monitoring of a person's health status who is located in a dangerous environment. Examples of these situations include firemen, rescuers and even mountain tourists where lower oxygen level may cause loss of consciousness and possible death.

Description of Space, Resource, and Specialty Equipment Used

Our lab is equipped with basic optical components such as light sources, beam-shaping components, photodetectors and spectrophotometers. These components can be used to conduct basic spectrophotometric experiments on biological samples (e.g. blood) or to perform non-invasive measurements. The lab houses a light-shielded Faraday cage that can be used to conduct light-sensitive and low-noise experiments.

Our lab is also equipped with various electronic testing equipment (e.g. power supplies, function generators, oscilloscopes, digital multimeters) for developing sensors and instrumentation. In addition, the lab is equipped with a wire bonding machine that is used for prototype development and testing of miniature optical sensors. Several PCs interfaced with dedicated data acquisition hardware and LabView software are available for signal acquisition and processing.

Lab Pictures

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Last modified: September 20, 2006 15:16:31