Originally Published EMDM October 2001
Flexible batteries that are safe enough to eat may soon increase design freedom for a host of disposable products that require thin, environmentally friendly, and inexpensive power sources. Eliminating the bulky metal casing that often prohibits miniaturization, these new batteries from Power Paper (Kibbutz Einat, Israel) consist of a unique, biologically safe manganese dioxide core encased within a flexible polyester housing, a construction not possible with conventional power sources because they contain hazardous chemicals that require containment.
"Traditionally, it has been the metal case of a battery that limits design freedom," says CEO Baruch Levanon. "But since our batteries don't pose a threat to either humans or the environment, we can use a plastic housing that lets us make smaller products in almost any shape," he says.
Like standard batteries, these innovative products work by converting chemical energy to electrical energy in a cyclical process. Power Paper batteries have a 1.5-V core chemistry and a capacity of 2.5 mA/cm2. Units can be constructed in most shapes and sizes, with a maximum power output of 12 V. Just 0.5 mm thick, the flexible components can bend up to 90° without affecting functionality. Acceptable operating temperatures span –20° to 60°C. Other features include a shelf life of 2.5 years, compatibility with radiation and EtO sterilization processes, and a flat discharge curve.
Power Paper batteries are produced using a modified screen-printing method that combines several wafer-thin layers into a single flexible package. This package is then pasted or laminated onto a substrate to create the finished product. With dimensions ranging from 1 sq in. to the size of a whole sheet of A4 paper, there is a battery available for most applications. While the process currently requires special equipment, company officials say it will soon be possible to produce these products using standard printing presses.
Medical and diagnostic sensors are among the many products that stand to benefit from this novel technology. Levanon says Power Paper batteries are ideal for these products, as they "provide optimal performance at the body's temperature and humidity conditions." Possible applications include continuously reading thermometer patches, wireless electrodes, and glucose, pH, bilirubin, and coagulation monitors. Drug-delivery systems that use iontophoresis to supply medicines accurately at the appropriate times are another potential application.
Currently in production, devices that incorporate Power Paper batteries are expected to reach store shelves before the end of the year. Manufacturers can license the technology to produce the batteries at their own facilities, or purchase finished units from subsidiary Thinergy Ltd. (Hong Kong).
For more information, contact Power Paper Ltd., Kibbutz Einat, Israel 49910; phone: +972 3 9007525; fax: +972 3 9007505; Internet: http://www.powerpaper.com.
Zachary Turke
Copyright ©2001 European Medical Device Manufacturer
