Electronics technology continues to make an astonishing impact in medicine. An entire biomedical industry has emerged with sophisticated diagnostic, treatment, and surgical systems that are extending our lifespans and giving us far more enjoyable lifestyles. Research and design efforts are reaching down into the atomic and molecular levels to better understand and create biomedical systems that interact more smoothly with the human body.
The biomedical industry is targeting a wide variety of potential applications that dazzle the mind, like DNA sequencing, biometrics, genetically engineered drugs, assay development and distribution, point-of-care instruments, and military devices that can detect chemical and biological agents.
DRUG DELIVERY A particularly exciting area in the biomedical field is the development of "smart" implantable drug-delivery systems that can detect chemical signals in the body and release appropriate therapeutic dosages for treatment (Fig. 1). The aim is to make highly effective drugs that can precisely target certain diseases and minimize side effects. Many of these systems have been approved by the U.S. Federal Drug Administration (FDA) and are already on the market. Far more sophisticated systems should be ready in two to three years.
Eventually, nanoresearch and developments will lead to drug-delivery systems that use body cells and molecules. Protein biomolecules have been shown to act as switches for highly selective drug delivery. Living cells have been used as control elements, instead of electrical or mechanical energy, to pump tiny amounts of fluid into the body.
Implantable fluorescent molecular probes, specific proteins combined with light-emitting molecules, constitute another increasingly critical part of biomedicine. Already available are probes for diagnostic, forensic, pharmaceutical, and genomic screening tests for the early detection of diseases like cancer and HIV. Their optical sensors detect the probe's glow when the probe's molecule encounters the RNA of a cancer or HIV cell. But these glows aren't bright enough for many tests. As a result, researchers are developing a new class of light-emitting polymers that can boost the glow factor by at least 25 times for much more sensitive screening tests. Such work is expected to bear fruit in one to two years.
IMPLANTABLE DEVICES Within a couple of years, matchstick-size implantable stimulation devices will treat millions who suffer from such conditions as Parkinson's disease, sleep apnea, limb paralysis, strokes, epilepsy, and urinary incontinence. These devices will be powered by advanced microminiature batteries that can be recharged from outside the body, with no physical connections, and will be designed to last for 10 years or more.Research is under way for implantable silicon neuron chips involved in brain repair. In some cases, researchers are building system-on-a-chip (SoC) ICs, mixing analog and digital circuitry, which can be implanted in the brain to treat stroke, epilepsy, and Alzheimer's disease. While this phase of the work is presently being performed on animals, some researchers are confident that human trials will take place within three to five years.
One notable implantable stimulator, a stomach pacemaker, will help overweight individuals lose weight without surgery. Already in human field trials, it should be ready within three years. Under development by Transneuronix (www.transneuronix.com), the pacemaker consists of a long, flexible wire attached to a pocket-size metal case that contains a battery and an electronic controller (Fig. 2). The electrode-bearing wire is implanted into the muscle around the stomach using a laparoscopic procedure on an out-patient basis, and the case is inserted under the patient's abdominal skin. When the device is activated two weeks later, it delivers high-frequency electrical pulses to the stomach to simulate the feeling of "fullness" and thus curb the need to eat.
Future projects will involve injectable neuromuscular stimulators for the paralyzed. These could be managed by wireless communications control systems sewn on a paralyzed person's sleeve. Also on the horizon are curved silicon-based arrays of photosensors that can be fitted on the back of a damaged eye's retina for improved vision.
The FDA has approved implantable neurostimulators and drug pumps for treating chronic pain, spasticity, and diabetes. Thin, insulated, coiled wire is implanted under the skin on the head. The wire extends down the neck and into the upper chest. Patients control the stimulation procedure via external sealed neurostimulator modules.
Even conventional surgical tools have reaped the benefits of technological advances. In one experiment, researchers demonstrated that magnetically controlled catheters can be steered through blood vessels remotely and more accurately than conventional manual means. The catheter's tip is encircled by copper coils. Using a joystick, the physician monitors and controls the catheter as current flows through the coils. This type of work may lend access via catheters to other parts of the body, like the brain, which have heretofore not been possible.
The ordinary surgical knife is now becoming a "data knife," such as the one coming from Verimetra (Fig. 3). Embedded in the knife are a pressure sensor, sensing/stimulating electrodes, ultrasonic cutting elements, a cauterizer, and strain sensors. This MEMS-based knife is designed to help surgeons navigate through delicate surgical procedures on newborn babies. The smart scalpel would guide a surgeon's hand and measure temperature, force, and pressure while the doctor repairs a newborn's defective heart. The company expects this device to be on the market within two years.
Clearly, the imagination holds no bounds as to how far electronics will go in the medical field. We can certainly expect to live longer and better lives thanks to electronics technology.