Originally Published MPMN October 2001

Paper-Thin Flexible Batteries Create New Design Options

Flexible batteries that are safe enough to eat may soon increase design freedom for a host of disposable products including medical sensors that require thin and environmentally friendly power sources. Eliminating the bulky metal casing that often prohibits miniaturization, these new batteries from Power Paper (New York City; www.powerpaper.com) consist of a biologically safe manganese dioxide core encased within a flexible polyester housing. This construction is not possible with conventional power sources, which contain hazardous chemicals that must be contained. "Traditionally, it has been the metal case of a battery that has limited 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."

Power Paper products work like standard batteries and have a range of features. With a 1.5-V core chemistry and a capacity of 2.5 mA/cm², units can be constructed in most shapes and sizes to a maximum power output of 12 V. The flexible components are 0.5 mm thick and 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.

The 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 directly onto the substrate of the finished product. With dimensions ranging from 1 sq in. to the size of a 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 because the power sources "provide optimal performance at the body's temperature and humidity conditions." Possible sensor applications include continuously reading thermometer patches; wireless electrodes; and glucose, pH, bilirubin, and coagulation monitors. Drug-delivery systems that use iontophoresis to accurately supply medication are another potential application.

Devices that incorporate Power Paper batteries are currently in production and are expected to reach store shelves by the end of the year. Manufacturers have the option of licensing the technology to produce the batteries at their own facilities, or purchasing finished units from Power Paper's subsidiary Thinergy Ltd. (Hong Kong).

Zachary Turke

Copyright ©2001 Medical Product Manufacturing News