by Bob Haavind, Editorial Director
Advances in technology are bringing rapid progress in many areas of medical technology, and their use should increase dramatically over the next few years, predicted Kensall Wise, U. of Michigan, in a plenary talk at the International Electron Devices Meeting (IEDM) in San Francisco in December. Advances should go far beyond the pacemakers already used by millions of heart patients.
The needs for such devices, from DNA chips and implanted wireless blood analyzers to cochlear and retinal implants, should also boom as senior citizens in the US (>60 years of age) rise from about 10% in 2000 to more than 20% in the next decade of so.
While pressure sensors for the cardiovascular system have a long history, for example, implantable microsystems that measure arterial pressure and flow on demand can be powered, controlled, and read out inductively, and are being incorporated in stents. Pressure sensing devices that can run on nanowatts are being explored to treat glaucoma.
Studies of biological systems are being greatly enhanced using implanted sensors in order to devise better electronic devices within the emerging science of biomimetics, according to Wise, adding that it is widely expected that progress in biotechnology and healthcare technology over the next 50 years will be comparable to what we have seen in microelectronics over the past 50 years.
He showed dramatic videos of Parkinson’s patients with carefully positioned four-electrode probes embedded in the brain’s subthamic nucleus receiving signals from pacemaker-like devices that immediately stopped uncontrollable trembling. One man whose hand had been vibrating steadily received the brain stimulation and was able to stand up and shake the doctor’s hand without any sign of trembling.
Understanding of various neurophysiological diseases is increasing steadily by monitoring signals from implanted devices, and corrective devices and signals are steadily improving as a result. Devices under development include retinal implants for the blind, cortical implants for paralysis, and implants for managing epilepsy. Implanted electrode arrays in primates have enabled them to learn to operate robotic arms using “thought control,” providing great promise for paraplegics and quadriplegics.
Developments in microelectromechanical systems (MEMS), low-power wireless devices, and materials that interface well with human tissue, are all contributing to steady progress in both understanding biological processes and improving the performance of electronics and signals used to treat handicaps or disorders. While many devices are built on silicon, some also use metals (especially gold) and polymers. Some labs, such as at the U. of Utah, are refining techniques to make multiple probes, and parts that are not as bio-compatible as others can be coated with parylene.
Packaging enabling devices to last for many years without interacting with nearby tissue is critical to making many of these implanted devices practical. But designs are also based whenever possible on commonly used materials and processing techniques to keep costs down. Miniaturization and very low power are also essential, so work going on in areas such as RFID and smaller portable devices such as camera phones, should also contribute to the steady progress in a widening range of wireless implantable devices. — B.H.