IEEE EMBS presents

Wearable & Implantable Technologies

Given rising healthcare costs, there has been an ongoing move toward shorter and shorter hospital stays. Patients are going home sicker and require ambulatory health monitoring. Many patients are living with chronic diseases which need to be managed. And our population is aging, with many older citizens who either cannot afford to—or do not want to—live in an assisted living facility. Oftentimes, the elderly live alone or are left alone during the day. And so there is a need to be able to look out for their safety.
Technological advancements have lead to the miniaturization of monitoring devices and power sources, opening up a whole new world of possibilities and innovations. And the powerful, portable computers we continue to refer to as “cell phones” now weigh so little and can do so much real-time monitoring has now become viable for an array of applications.
Wearable and implantable technologies sense parameters of various diseases and can either transfer data to a remote center, direct the patient to take a specific action, or automatically perform a function based on what the sensors are reading. For example, if blood glucose is running high, insulin could be automatically administered.

Heart Monitoring

Cardiac outpatients experiencing arrhythmias who need their heart monitored for an extended period of time have traditionally worn a Holter monitor for 24 hours, an event recorder used intermittently over 24 to 48 hours or a continuous loop recorder that captures and transmits a few minutes’ worth of recordings. But none of these solutions is ideal and clinically significant arrhythmias can be missed. CardioNet’s Mobile Cardiac Outpatient Telemetry™ (MCOT™) unit is worn continuously for up to 21 days. Based on physician-selected events to be monitored and the chosen reporting speed, the device automatically transmits detected events to the CardioNet Center, which then relays reports to a patient’s physician.
For patients suffering from infrequent and unexplained fainting episodes, longer-term monitoring is required. Medtronic’s Insertable Cardiac Monitor is implanted just under the skin for long-term use, eliminating the wires and recording pads of shorter-term solutions. This loop recorder is constantly monitoring signals from the heart, keeping only a few minutes of the recording at a time. When a spell occurs, the patient or a family member uses a hand-held activator to trigger the device to capture the period before, during and after the spell.

Monitoring Parkinson’s

The severity of symptoms in patients with Parkinson’s disease can vary greatly between doses and throughout the day. A neurologist typically spends just a few minutes with a patient and, to physically get to their appointment, the patient has to medicate appropriately. So it can be a challenge to render an accurate assessment of a patient’s status and their need for medication adjustment. Further confounding medication decision-making, patients often confuse the tremor of Parkinson’s with drug-induced dyskinesias, making self-reports unreliable.
Backed by the Michael J Fox Foundation and the NIH, researchers at Harvard are exploring ways to monitor motion patterns of Parkinson’s patients at home and infer the severity of Parkinsonian symptoms. Early proof-of-concept studies using accelerometers on the upper and lower limbs were able to detect the severity of both tremors and dyskinesias to the same level of accuracy as the assessments of neurologists.
Similar approaches could be used to detect exacerbation episodes in COPD, changes in functional abilities in stroke survivors undergoing rehabilitation, seizures in patients with epilepsy and other medical events in which time is of the essence. The exact way the patient is monitored and the type of data collected and transmitted differ based on the disease in question.

Smart Tattoos

Continuous monitoring can occur via wireless monitors, wireless patches and articles of clothing. But cost is, of course, an issue—as is patient compliance.
Researchers at the University of Illinois—working with colleagues in Singapore—have figured out how to embed flat, flexible, stretchable electronic sensors into temporary tattoos that can withstand wrinkling, bending and twisting of the skin. These micro-electronics, which are thinner than a human hair and applied with water, could be used to provide irritation-free monitoring of electric signals produced by the heart, brain and muscles.

Photo: John A. Rogers

The applications are wide-ranging. The tattoos could be used to monitor heart arrhythmias, sleep disorders and the heart activity of premature babies; stimulate muscles; and serve as a human-computer interface when applied to the throat by using vibrations from the vocal chords to control a computer. Additional detectors, transmitters and receivers can also be included on the tattoo.
Currently powered via solar cells and a wireless transmitter, the developers are hoping to include a tiny battery. They also hope to someday be able to interpret chemical information from the skin.

Dermally-Implanted Sensors

Blood chemistry is the focus of researchers at Texas A&M University. They are working on micro-particles that can be injected into the highly-vascular dermis layer of the skin and change color to reflect changes in blood chemistry. These “active” inks are luminescent; imperceptible to the naked eye and visible only by using a special light.

The microparticle sensor concept: implantation, interrogation, and readout.

Patients can be monitored using a range of techniques, from wearable devices that require patients to actively participate and be compliant, to unobtrusive environmental monitoring and temporary or implantable devices.
Wearable and implantable technologies have the potential to provide significant savings—in both costs and lives. For any device to be successful, however, it has to be designed in such a way that it is inexpensive for the payer, unintimidating for the user and both accurate and reliable for everyone.

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