Seismocardiography (SCG), a representation of mechanical heart motion, may more accurately determine periods of cardiac quiescence within a cardiac cycle than the electrically derived electrocardiogram (EKG) and, thus, may have implications for gating in cardiac computed tomography. We designed and implemented a system to synchronously acquire echocardiography, EKG, and SCG data. The device was used to study the variability between EKG and SCG and characterize the relationship between the mechanical and electrical activity of the heart. For each cardiac cycle, the feature of the SCG indicating Aortic Valve Closure was identified and its time position with respect to the EKG was observed. This position was found to vary for different heart rates and between two human subjects. A color map showing the magnitude of the SCG acceleration and computed velocity was derived, allowing for direct visualization of quiescent phases of the cardiac cycle with respect to heart rate.

Sensing systems-on-chip (SSoCs), combining micromachined sensing structures and microelectronic building blocks on a single chip, are reviewed. While single-chip pressure and inertial sensing systems have been commercially available for more than a decade, the recent expansion of SSoC into new application areas, ranging from chemical and biochemical sensing to atomic force microscopy, demonstrates the full potential of this microsensor integration approach. Available fabrication processes for integrated sensing systems are summarized, categorizing them into pre-, intra-, and post-CMOS approaches depending on the way the micromachining module is merged with the integrated circuit (IC) technology. Examples of SSoCs are presented to highlight the different integration options, ranging from cointegration of micromachined sensors with purely analog signal chains to microsystems with cointegrated digital signal processors and digital interfaces.

Microfabrication processes for chemical and biochemical sensors are reviewed. Standard processing steps originating from semiconductor technology are detailed, and specific micromachining steps to fabricate three-dimensional mechanical structures are described. Fundamental chemical sensor principles are briefly abstracted and corresponding state-of-the-art examples of microfabricated chemical sensors and biosensors are given. The advantages and disadvantages of either fabricating devices in IC fabrication technology with additional microfabrication steps, or of using custom-designed nonstandard microfabrication process flows are debated. Finally, monolithic integrated chemical and biological microsensor systems are presented, which include transducer structures and operation circuitry on a single chip.

Today, learners on the move are typically disconnected from their learning environment and from other learning partners. With the advances in mobile communication, we envision distributed and mobile learners to be seamlessly connected to learning sessions and learning content. Connection should be supported in an ad-hoc fashion, if applicable, and during mobility. Mobile learners are usually equipped with mobile devices, such as laptops or handheld computers (PDAs). This has to be considered for the development of collaborative applications. Furthermore, an integration of existing collaborative frameworks in to interactive workspaces is investigated. This requires the development of new learning scenarios that provide support for such integration.

An integrated circuit (IC) approach to thermal microsensors is presented. The focus is on thermal sensors with on-chip bias and signal conditioning circuits made by industrial complementary metal-oxide-semiconductor (CMOS) IC technology in combination with post-CMOS micromachining or deposition techniques. CMOS materials and physical effects pertinent to thermal sensors are summarized together with basic structures used for microheaters, thermistors, thermocouples, thermal isolation, and heat sinks. As examples of sensors using temperature measurement, we present micromachined CMOS radiation sensors and thermal converters. Examples for sensors based on thermal actuation include thermal flow and pressure sensors, as well as thermally excited microresonators for position and chemical sensing. We also address sensors for the characterization of process-dependent thermal properties of CMOS materials, such as thermal conductivity, Seebeck coefficient, and heat capacity, whose knowledge is indispensable for thermal sensor design. Last, two complete packaged microsystems-a thermoelectric air-flow sensor and a thermoelectric infrared intrusion detector-are reported as demonstrators.