Optical systems to evaluate volume of medical samples in opaque test tubes.

摘要

Measuring volume in medical samples without removing the cap of the tube is an important first step in highly automated biomedical laboratories. The variations of liquid properties, tube material, and number as well as location of labels attached to the outside of the test tube are the key points that prevent use of most traditional methods. Research into optical level detection was conducted to resolve the above issues. The research focuses on the optical detection of liquid level and volume of medical samples in the test tubes that are covered by an unknown number of labels. It has been carried out at the Precision Design Laboratory in the Department of Mechanical Engineering at University of Utah since 2006. The project is funded by the ARUP Institute for Clinical and Experimental PathologyRTM (ARUP).;This research mainly investigates optical methods that detect the liquid level through the side of the test tube. By analyzing the change of power of transmitted light, which passes through the sample, the location of the interface between air and liquid inside the test tube is determined.;To study the effect of loss of light through sample tubes, the propagation process is modeled and simulated through a ray tracing method. Experiments were conducted to verify the modeling and simulation.;In this research, two detection principles based on the light propagation principle were developed, and their application systems were prototyped. The first one is a Max/Min Level Detection System, which can verify the minimum and maximum liquid levels in test tubes by computing the power ratio of two wavelengths. The second system is referred to as a Volume Detection System, which takes into account the volume of the meniscus by identifying the height and position of the meniscus.;In order to determine the liquid volume in different types of test tubes by the liquid level, a machine vision system was developed to identify the type of tube and retrieve the relevant geometric data from a database. An experimental prototype was set up and experiments were conducted to verify the functionality of the system.