Monolithic cathodes of optimized porosity prepared by sintering LiCoO2 powders provide high volume utilization and surprising stability under electrochemical cycling. Combined with a novel packaging approach, ultrahigh energy densities in small volumes are enabled. The microbatteries have volumes <6 mm3 and provide sustained ∼2.5 h discharges with energy densities of 400–650 W h L−1.

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MEMS-based products produced in 2005 had a value of $8bn, 40% of which was sensors. The balance was for products that included micromachined features, such as ink jet print heads, catheters and RF IC chips with embedded inductors. Growth projections follow a hockey stick curve, with the value of products rising to $40bn in 2015 and $200bn in 2025! Growth to date has come from a combination of technology displacement, as exemplified by automotive pressure sensors and airbag accelerometers and new products, such as miniaturised guidance systems for military applications and wireless tire pressure sensors. Much of the growth in MEMS business is expected to come from products that are in the early stages of development or yet to be invented. Some of these devices include disposable chips for performing assays on blood and tissue samples, which are now performed in hospital laboratories, integrated optical switching and processing chips, and various RF communication and remote sensing products. The key to enabling the projected 25fold growth in MEMS products is development of appropriate technologies for integrating multiple devices with electronics on a single chip. At present, there are two approaches to integrating MEMS devices with electronics. Either the MEMS device is fabricated in polysilicon, as part of the CMOS wafer fabrication sequence or a discrete MEMS device is packaged with a separate ASIC chip. Neither of these approaches is entirely satisfactory, though, for building the high-value, system-onchip products that are envisioned. It is this author's opinion that a combination of self-assembly techniques in conjunction with wafer stacking, offer a viable path to realizing ubiquitous, complex MEMS systems.

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An implanted neural stimulator with closed loop control requires electrodes for stimulation pulses and recording neuron activity. Our system features arrays of 64 electrodes. Each electrode can be addressed through a cross bar switch, to enable it to be used for stimulation or recording. This electrode switch, a bank of low noise amplifiers with an integrated analog to digital converter, power conditioning electronics, and a communications and control gate array are co-located with the electrode array in a 14 millimeter diameter satellite package that is designed to be flush mounted in a skull burr hole. Our system features five satellite packages connected to a central hub processor-controller via ten conductor cables that terminate in a custom designed, miniaturized connector. The connector incorporates features of high reliability, military grade devices and utilizes three distinct seals to isolate the contacts from fluid permeation. The hub system is comprised of a connector header, hermetic electronics package, and rechargeable battery pack, which are mounted on and electrically interconnected by a flexible circuit board. The assembly is over molded with a compliant silicone rubber. The electronics package contains two antennas, a large coil, used for recharging the battery and a high bandwidth antenna that is used to download data and update software. The package is assembled from two machined alumina pieces, a flat base with brazed in, electrical feed through pins and a rectangular cover with rounded corners. Titanium seal rings are brazed onto these two pieces so that they can be sealed by laser welding. A third system antenna is incorporated in the flexible circuit board. It is used to communicate with an externally worn control package, which monitors the health of the system and allows both the user and clinician to control or modify various system function parameters.