Microwave frequency sensor for detection of biological cells in microfluidic channels

We present details of an apparatus for capacitive detection of biomaterials in microfluidic channels operating at microwave frequencies where dielectric effects due to interfacial polarization are minimal. A circuit model is presented, which can be used to adapt this detection system for use in other microfluidic applications and to identify ones where it would not be suitable. The detection system is based on a microwave coupled transmission line resonator integrated into an interferometer. At 1.5 GHz the system is capable of detecting changes in capacitance of 650 zF with a 50 Hz bandwidth. This system is well suited to the detection of biomaterials in a variety of suspending fluids, including phosphate-buffered saline. Applications involving both model particles (polystyrene microspheres) and living cells—baker’s yeast (Saccharomyces cerevisiae) and Chinese hamster ovary cells—are presented.     

Designing Effective Learning Environments for Continuing Education

Advances in technology for distance learning present better‐than‐ever opportunities for designing learning environments that bring optimal features of the conventional classroom to distributed learners. Yet, with the advantages of reaching learners come corresponding challenges for meeting many and varied cognitive, motivational, and organizational needs. Anchoring design of distance learning instruction solidly in current research from cognitive science and motivation, as well as utilizing tested principles of instructional design theory, provides for optimal balance of strategic decision‐making and appropriate management of trade‐offs in design of effective learning environments. This paper shows how Bransford, Brown, and Cocking's (1999) four characteristics of effective learning environments can be developed for continuing education, to maximize learning, transfer of learning, and motivation. As illustration, I will focus on the process of translating traditional continuing education (CE) from lecture‐based, on‐site instruction to Web‐based instruction, a trend in many institutions of higher education.