text: 1. Field
  Apparatuses and methods consistent with exemplary embodiments relate to a microfluidic device and a method of detecting a sample supplied to the same, and more particularly, a microfluidic device having an improved structure capable of determining whether an appropriate amount of sample is inserted or not, and a method of detecting a sample supplied to the same.
  2. Description of the Related Art
  Various methods for analyzing samples have been developed in various fields of application, such as environmental monitoring, food inspection, and medical diagnostic field, but related art test methods require a significant amount of manual labor and various devices. In order to perform a test according to a defined protocol, a skilled experimenter should proceed with a variety of steps, such as performing a number of reagent injections, mixing, separation and moving, reaction, and centrifugation, and this test method may become a critical cause of inducing errors in the test results.
  In order to perform the test quickly, skilled medical technologists are needed. However, there may be difficulties for the skilled medical technologist to run several tests at the same time. In the diagnosis of an emergency, rapid test results are very important to provide fast first aid. Thus, an apparatus may be needed that is capable of rapidly and accurately performing a number of pathological tests required according to situations, at the same time.
  In the related art pathological tests, large and expensive automatic apparatuses may be used, and a sample, such as a relatively large amount of blood, may be needed. In addition, it may take a lot of time, e.g., from 2˜3 days to 1˜2 weeks, to obtain the results after samples are taken from the patient.
  To relieve these difficulties, a miniaturized and automated apparatus capable of analyzing a sample taken from one patient or a small number of patients quickly as needed may be used. For example, blood is inserted into a disc type microfluidic device, and serum is separated from blood by the centrifugal force generated by the rotation of the microfluidic device. The separated serum is mixed with a certain amount of diluent, and then moved to a plurality of reaction chambers in the disc type microfluidic device. In the plurality of reaction chambers, different reagents different from each other according to blood test items are injected in advance, and thus, the reagent makes a color by reacting with the serum. By detecting the change of the color, the blood analysis may be performed.
  When an amount of a sample injected into a microfluidic device is insufficient, it may be difficult to perform centrifugation and metering and thus the wrong test results may be calculated. Therefore, whether the amount of a sample injected into the microfluidic device is sufficient may enormously influence the test results. For example, whether the amount of a sample injected into the microfluidic device is sufficient may be confirmed by measuring the optical density. In general, when an amount of a sample is sufficient, the optical density may be measured to be higher than the reference optical density, and when the amount of a sample is insufficient, the optical density may be measured to be lower than the reference optical density. However, although the amount of a sample is sufficient, the optical density may be measured to be lower than the reference optical density and thus it may be determined that the amount of a sample is insufficient.