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Inductive powering can free microelectromechanical systems (MEMS) devices from tethering to a power supply, thus expanding their scope of applications. We investigate inductive powering for MEMS using a microfabricated coil as a receiver operating at and below 1 MHz. The microcoil is designed to enclose the MEMS functions to achieve maximum coupling, and is built into a silicon substrate by our inlaid electroplating process, so that the microcoil has a small resistance despite its long trace. Non-negligible parasitic effects from the silicon substrate affect the characterization of an inductive link and its optimization. Taking into account the parasitic effects of Si microcoils, the coupling coefficient of the link is determined by a coil-model scheme that is different from conventional strategies. Furthermore, an equivalent circuit is developed for our link and used to analyze link operation over the frequency range of 4 kHz to 4 MHz. With measured link parameters, link efficiency is calculated with our equivalent circuit, and the results agree better with experiments than do conventional models. The equivalent circuit also indicates that microcoils with high quality factor at low frequencies, such as our inlaid electroplated coils, improve link performance, while parasitic capacitance has little effect.

In order to free microelectromechanical systems and other microsystems from wire tethering, an inductive link with integrated receiving coil is shown to transfer power onto silicon chips. Link efficiency (ratio of power delivered to the load to power into the driving coil) benefits from receiver coils with both large interception areas and low resistances, contradictory conditions for integrated coils due to high specific resistance from planar fabrication. To address this, an 'inlaid electroplating' procedure is developed to fabricate microcoils on silicon substrates. Copper coils of 14 mm side length, 54 ?m height and 100 ?m pitch are electroplated and planarized to allow further lithography. Sidewalls between Cu lines are selectively removed to modify coil capacitances. Thin film and electroplated microcoils with and without sidewalls are characterized and compared as link receivers. Little difference in power delivery is observed between plated microcoils with and without sidewalls. Powering efficiency to a 50 ? load reached 85% for a link coupling of ~0.75. Since link properties are affected by parasitic effects from silicon chips, an equivalent circuit is developed, providing a good prediction of link efficiency. Link optimization is discussed using our model.

The paper presents thoughtful writing by under‐privileged 7‐8 year olds, and analyses how they got there. An introductory lesson is detailed, along with a number of supporting strategies of content and method. This treatment is then critically placed in a context of cognitive psychology and of philosophy of education.

This paper attempts three things. It invites you to engage critically with me in the adjudication of a particular controversy. It attempts to argue for and exemplify important procedures which distinguish good and bad thinking in a critical mode. And it argues the case for the separate teaching of critical thinking (henceforth CT).

With recent developments in micromachining technology, fabrication of discrete microdevices is maturing; consequently, system integration is becoming an ever more important issue. One obstacle to such systems is the diverse power requirements of microdevices, especially actuators. Since some types of actuators exhibit relatively high voltage or power requirements, it is not feasible to integrate power supplies on-chip, and it is often inconvenient for the MEMS system to be tethered to interconnects for purposes of supplying power. On-chip wireless power sources can be implemented to circumvent this problem.