Picture this: A heart patient is experiencing fluid buildup in the lungs—an early sign of heart failure. But, an implantable sensory medical device in the patient emits a signal to both the patient and his physician via a Bluetooth-equipped mobile phone, warning them of impending danger. Wishful thinking? Not really. The technology is already here and is continuously being refined. All that’s missing is the supporting infrastructure.
Mir Imran, an inventor and entrepreneur at InCube Inc., presented this scenario as part of a panel on medical electronics at last month’s 2009 International Consumer Electronics Show (CES) in Las Vegas. The panelists discussed the vast potential of implantable devices that can accurately and quickly monitor and treat patients anywhere for chronic ailments such as heart disease, epilepsy, diabetes, and Parkinson’s disease.
And there’s much more to improving healthcare than sensory implants. Devices like insulin pumps are now available to service entire organs. Implantable vision systems are making notable progress. Microelectromechanical-system (MEMS) and carbon-nanotube (CNT) neural implants are providing a vast range of information about how human beings behave.
The tools needed to diagnose and treat many health conditions are improving daily. Some surgical instruments can access nearly every part of the human body via catheters. Slowrelease drug capsules are becoming more effective and enhancing diagnostics and treatments. Externally wearable devices are vital to applications such as therapeutics. And, lab-on-a-chip devices can quickly sample, diagnose, and report on a patient’s vital medical signs.
Healthcare technology is poised to fulfill an urgent need. Roughly 80% of global healthcare costs are used to treat chronically ill aging patients. Some 600 million patients suffer from chronic diseases like diabetes, chronic obstructive pulmonary disease (COPD), congestive heart failure, and epileptic disorders. Longer lifetimes, a shortage of healthcare professionals, and spiraling healthcare costs all exacerbate the situation.
“Healthcare is a $2.5 trillion market in the United States alone,” says Andrew Rocklin, an analyst at Diamond Management & Technology Consultants. “Anybody who chooses not to participate could be giving up a potentially large amount of revenue.” But hurdles must be overcome before technology can have a real impact. Chief among them is a healthcare system, here in the U.S. as well as worldwide, that needs reform (see “Making The Healthcare System Technologically Friendlier” at www.electronicdesign.com, ED Online 20624).
HELP FOR DIABETICS AND HEART PATIENTS
Debiotech Inc. and STMicroelectronics announced the first prototypes of a disposable insulin pump patch (Fig. 1). Using microfluidic MEMS technology, the Nanopump passed initial testing stages and has been ready for volume manufacturing since last summer. Just one-fourth the size of existing insulinpump devices, it can be worn as a nearly invisible patch on the skin.
The Nanopump uses continuous subcutaneous insulin infusion (CSII), closely mimicking the natural secretion of insulin from the pancreas , whi l e detecting potential pump malfunctions for patient safety. According to the companies, it costs less and is a more attractive alternative than individual insulin injections that must be administered several times a day.
University of Michigan researcher Mark Meyerhoff is working for the U.S. Army Research Laboratory on subcutaneous implantable glucose sensors that monitor diabetes patients in real time. He’s using polymeric materials that catalyze the generation of nitric oxide (NO) at low concentration levels. Applied as coatings on surgically implanted amperometric glucose sensors, these materials would be more biocompatible than previous efforts since they reduce inflammations caused by implanted sensors. Cardiovascular disease is a common cause of death and disability. Heart diseases including arrhythmias result in about a third of all deaths in the U.S., spurring the development of a variety of medical monitoring devices and tools. One such device is a wireless electrocardiogram (ECG) patch monitor designed by Belgium’s IMEC (Fig. 2).
The monitor integrates electrodes, a biochip sensor, a microcontroller unit, and a radio in a package the size of a very thin wristwatch. Algorithms running on the patch’s processor monitor patients for arrhythmias day and night. The patch can run on a small 20- by 20- by 5-mm battery for about a week, with average power consumption of 2 mW.
A notable advance in therapeutic tools for cardiac rhythm disorders can be seen in a force-sensing ablation catheter from Endosense that treats cardiac disorders. The Switzerland-based company developed the first force-sensing force-ablation catheter, which gives physicians real-time objective measurement of the contact during a catheter-ablation procedure.
Physicians have treated this condition with conventional surgery to create lesions in the heart’s walls to eliminate abnormal cardiac electrical activity. But it’s difficult for physicians to assess whether or not they have created optimal lesions because there hasn’t been an accurate way to measure the force of the probe used to create them.
The TactiCath catheter is threaded up through a vein in the patient’s groin to the upper chambers of the heart. Through RF waves, it targets regions along the heart’s wall. Fluoroscopy, 3D mapping, and ultrasound provide outside guidance. Force, amplitude, and direction data are transmitted to a monitor from the catherer’s tip, giving physicians complete control over the ablation procedure (Fig. 3).
Germany’s Fraunhofer Institute for Microelectronic Circuits and Systems came up with an implantable blood-pressure sensing system, which is a goal for many researchers. Unlike cardiac pacemakers, the system doesn’t require an internal battery, since it’s powered inductively from outside the body. It consists of a sensor element and a transponder.
The sensor is inserted into an artery and connected to the transponder via microwires that are 10 to 15 cm long. The transponder, implanted under the patient’s skin, digitizes, pre-processes, and transmits blood pressure data. It’s powered through a tiny inductor that’s magnetically coupled with another inductor outside the patient’s body. This second inductor is part of a reading device carried by the patient.
The two inductors transmit electrical power to the transponder. At the same time, the inductors are used for wireless data exchange between the transponder and a reading device. Thus far, the researchers have been able to supply the implant with about 200 to 300 µW.
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