Development of Portable Fiber-Optic Laser Doppler Velocimetry Sensor for Measurement of Local Flow Velocity of Blood and Opaque Multi-Phase Fluids

为了测量血液和/或多相流体等不透明流体中的局部速度场，研制了一种新型光纤激光多普勒测速传感器。在获得几种不同稀释率的牛血和白色色素与水的混合物中的激光消光特性后，用本光纤传感器测量了装在旋转圆盘上的环形开口通道中的稀释牛血的流速。它的拾波器是由一个直径为2毫米的分布折射率透镜连接在两个并排平行连接的光纤的尖端。虽然传感器能够精确测量稀释血液的局部速度高达20%，但它不能测量较厚血液的速度，因为所使用的血液被认为具有比体内完整血液更差的质量。 关于我们 得到改善;首先，其尖端被成形为具有斜截圆锥，以便减少头部对流动的干扰，并且还减少从头部尖端散射的不期望的光。其次，采用直径为1mm的较小DIL透镜代替直径为2mm的DIL透镜，使其插入皮下注射器的针头内。第三，采用单光纤光学系统代替双光纤光学系统，提高了对不透明流体的灵敏度。第四，在光纤和DIL透镜之间使用通过紫外光硬化的粘合剂，以减少不希望的散射光。结果，半透明悬浮液的最大可测量浓度增加到原来的四倍。通过将结合在注射器针头内的改进的传感器头插入到硅橡胶的模拟血管中，测量了作为在管中流动的模拟血液的高浓度白色颜料悬浮液。结果，准确地获得了描述发展稳定层流的旋转抛物面的速度分布。因此，可以得出结论，成功的前景是良好的测量局部血流速度在体内血管直接插入传感器头。少

In order to measure the local velocity field in opaque fluids like blood and/or multi-phase fluids, a new fiber-optic laser Doppler velocimetry sensor has been developed. In the course of the present research for the development the followings have been elucidated :After obtaining the characteristics of laser light extinction in bovine blood of several different dilution rates and in mixtures of white pigment and water, the flow velocity of diluted bovine blood contained in an annular open channel which is placed on a rotating disc has been measured by using the present fiber optic sensor. Its pickup consists of a distributed index lens of 2mm in diameter attached at the tip of two fibers being joined side by side in parallel. Although the sensor is capable of making a accurate measurement of local velocity of diluted blood up to 20%, it cannot measure the velocity of thicker blood, because the blood used is considered to has worse quality than intact blood in vivo.The sensor head has … More been improved ; Firstly, its tip is shaped to have an obliquely truncated cone in order to decrease a disturbance of flow by the head and also to diminish undesirable light scattered from the tip of the head. Secondly, a smaller DIL lens of 1mm in diameter is adopted instead of the 2mm- diameter DIL lens to make it inserted inside of the needle of a hypodermic syringe. Thirdly, a mono-fiber optical system is adopted instead of the dual-fiber optical system to increase the sensitivity for opaque fluid. Fourthly, a bonding agent of being hardened by ultraviolet light is used between the fiber and the DIL lens to diminish an undesirable scattered light. As a result, the maximum measurable concentration of the semi-opaque suspension fluid is increase to be four times greater than the original one.By inserting the improved sensor head incorporated inside the syringe needle into a modeled blood vessel of silicone rubber, a high concentration suspension fluid of white pigment as a model blood flowing in the tube has been measured. As a result, the velocity distribution of a paraboloid of revolution characterizing the developed steady laminar flow is accurately obtained. Hence, it can be concluded that the prospect of success is good to measure the local blood velocity in blood vessel in vivo by directly inserting the sensor head into the vessel. Less