RESUMEN
Microfluidic flow generation plays a fundamental role in microfluidic systems and shows potential for applications in basic biology and clinical medicine. In this study, an enabling technology is proposed to quantitatively generate microfluid flow through the automatic movement of a microsphere in liquid by using optical tweezers. A closed-loop control strategy with visual servoing feedback is introduced to achieve high precision and robustness. The theoretical solution of the generated microfluid is obtained on the basis of Stokes equations. An experimental method is proposed, and experiments are performed to verify the effectiveness of our approach. This method does not impose any dedicated fabrication of microtool, and the microfluidic flow can be dexterously adjusted by controlling the direction, speed, and distance of the microsphere from a target location. To the best of our knowledge, this is the first demonstration of optically actuating liquids through the translational movement of microspheres with closed-loop control. The proposed method will be useful in various biomedical applications needing quantitative, precise and controllable localized microfluid.
RESUMEN
Applying ultrasound for scoliosis assessment has been an attractive topic over the past decade. This study proposed a new fast 3-D ultrasound projection imaging method to evaluate the spine deformity. A narrow-band rendering method was used to generate the coronal images based on B-mode images and their corresponding positional data. The non-planar reslicing method, which followed the natural spine curve, was used to project the complete spine data into the coronal image. The repeatability of the new method was tested. A comparison experiment on the reconstructed images and the processing time between the conventional 3-D rendering method and the developed projection imaging method was also performed among 70 patients with scoliosis. The intra- and inter-operator tests results demonstrated very good repeatability (ICC ≥ 0.90). The mean processing times for the developed projection method and conventional rendering method were 15.07 ± 0.03 s and 130.31 ± 35.07 s, respectively. The angle measurement results showed a high correlation (y = 0.984x, r = 0.954) between the images obtained using the two methods. The above results indicated that the developed projection imaging method could greatly decrease the processing time while preserving the comparative image quality. It can be expected that this novel method may help to provide fast 3-D ultrasound diagnosis of scoliosis in clinics.