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We present a systematic study of the Capillary number (Ca) effect on the capture efficiency of cancer cells on a composite microfluidic filtration chip. By altering the Ca in microchip experiments, the balance between the viscous force and the cell cortical tension affecting the capture efficiency has been investigated experimentally and analyzed theoretically. A 'Phase Diagram' for the capture efficiency of microfiltration chips is presented, for the first time, as a function of the normalized cell diameter and Ca. A critical value of Ca, around 0.03∼0.04, has been identified for enhancing the capture efficiency of cancer cells. The phase diagram is found to be consistent with the results of cancer-cell capture in microfiltration systems reported previously by others. The diagram can be a useful tool for designing the next generation microfiltration devices for isolating circulating tumor cells.

Our current practice at Hong Kong University of Science and Technology, HKUST, in both the Biology and Biochemistry departments is to provide laboratory experience to our undergraduates mostly through large class laboratory courses. The exercises performed therein are often very structured where specific cookbook-like manuals are followed. Students lack the opportunity to conduct or experience independent research until they reach their final year, where their final year project offers them the first hand experience through apprentice-style research activity. To increase the quality and range of learning opportunities to first and second year undergraduate biology students, we launched a discovery-based molecular genetics course. This type of discovery-based education is unique in Hong Kong. It provides students anticipating a research career the opportunity to have a glimpse of the operation of a research lab. This course enabled our undergraduate students to have hands-on experience on conducting experiments with undefined outcomes. The students started with a genetic mutant screen with the nematode, C. elegans, looking for a broad spectrum of developmental defects. The use of this simple model organism offered the flexibility for the student to explore a range of biological features. They then characterized the mutant isolates of their choice by developing their own hypotheses, critically thinking of their research foci and strategy with the advice of a team of tutors made up of post-graduates. The students were all enthusiastic and self-motivated about their individual projects. Within a short space of time they learnt different genetic, molecular and cellular techniques, bioinformatics as well as how to conduct scientific literature searches.