How to Control the Microfluidic Flow and Separate the Magnetic and Non-Magnetic Particles in the Runner of a Disc.

Biochips play an important role in both medical and food industry safety testing. Moreover, magnetic activated cell sorting is a well-established technology for biochip development. However, biochips need to be manufactured by precision instruments, resulting in the high cost of biochips. Therefore, this study used magnetic-activation and mechanics theories to create a novel disc that could manipulate the microfluidic flow, mixing, reaction, and separation on the runner of the disc. The goal of the research was to apply in the field of biomedical detection systems to reduce the cost of biochips and simplify the operation process. The simulation and experimental investigation showed that the pattern of the reaction chamber was stomach-shaped and the reservoir chamber was rectangular-shaped on the disc. The microfluid could be controlled to flow to the reaction chamber from the buffer and sample chamber when the disc spun at 175~200 rpm within three minutes. This was defined as the first setting mode. The microfluid could then be controlled to flow to the reservoir chamber from the reaction chamber when the disc spun at 225 rpm within five to ten minutes. This was defined as the second setting mode. This verified that the pattern design of the disc was optimized for control of the microfluid flow, mixing, reaction, and separation in the runner of the disc by different setting modes.

Prenatal ultrasonographic findings of esophageal atresia: potential diagnostic role of the stomach shape.

OBJECTIVE: We investigated prenatal sonographic characteristics of esophageal atresia (EA) with advancing gestation. We focused on the degree of polyhydramnios and the stomach shape. METHODS: This study included 27 EA cases (EA group) and 81 idiopathic polyhydramnios cases (non-EA group). The non-EA group consisted of cases without any fetal structural anomaly, musculoskeletal disorder, chromosomal abnormality, or maternal diabetes. Both groups included only singleton pregnancies. Amniotic fluid index (AFI) and width/length (W/L) ratio as well as the product of width and length (W×L) of stomach were serially assessed during gestation and compared between the 2 groups. To predict EA using W/L ratio and W×L, receiver operating characteristic curve analysis was performed. RESULTS: Polyhydramnios was evident in 77.8% of EA cases. We observed 25.9% and 22.2% EA cases with an absent stomach and a small visible stomach, respectively. After 28 weeks, the EA group manifested significantly higher AFI than the non-EA group. After 32 weeks, W/L ratio in the EA group tended to be lower than that in the non-EA group (32-36 weeks: 1.36 vs. 1.72, P=0.092; >36 weeks: 1.43 vs. 1.63, P=0.024). To predict EA, the calculated area under the curve for W/L ratio was 0.651 after 32 weeks. The diagnosis of EA using a cut-off value of W/L ratio <1.376 showed sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio to be 84.6%, 52.9%, 1.796, and 0.081, respectively. CONCLUSION: A low W/L ratio of stomach after 32 weeks with progressive idiopathic polyhydramnios may be used to predict EA.