Saturday, February 17, 2007

The medical dilemma


My heart goes out to the hearty few of you who click on my blog on the weekend. Hopefully I am not talking to a couple dozen automated Web crawlers!

Whoever you are, here's a little tidbit picked up at ISSCC this week.

Mingcui Zhou (left), a graduate student at the University of California at Santa Cruz, presented a paper on a 2 Mbit/s wireless transceiver for medical systems using a 20 MHz frequency. The 1.7x 2.6 mm device handles most of the signal sampling and processing in the analog domain to save power. It consumes 6.2mW, but has not yet been tested for meeting FCC regulations on that frequency.

Two Mbits may not seem like much for us Wi-Fi notebook mavens, but in the medical world, it's huge. Her advisor Wentai Liu said he needs 3 Mbits/s for the 1,024-electrode artificial retina he wants to design. Fat chance of getting it anytime soon.

Some implantable devices must last for years on the smallest battery possible, while others devices use what energy can be scavenged from RF signals. The implants themselves cannot generate more than one degree Celsius of heat for fear of burning body tissues.

The constrictions mean most systems are lucky to get data rates of 700 Kbits/second between an implant and an external programming device. A University of Southern California biomed professor, Gerald Loeb, speaking at ISSCC said he only gets about 120 Kbits/s on the toothpick-sized muscle stimulators he designs for paralyzed and impaired patients.

So if you want a real engineering challenge that makes a difference in people's lives, this is the place for you.

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