The Design Of Rapid Drug-testing Investigation

In recent years, drug hazards to human more and more and serious threat to human's normal life already. Therefore the detection of drug is very important,in particular the detection of drugs in vivo. This article is a device designed for detection drug in vivo.Using urine to determine the human health in the medical field is a method widely used. Because through the analysis of urine components can basically complete the judge of health and the extraction of urine samples is aslo convenient. The basic principle is that we strip the paper into the urine sample and observe the change of the color. For collecting the change of the color, the methods used commonly is visual inspection, optical integration, and spectrophotometry. Visual inspection is carried out by our eyes, we compare the color with the standard color. The mothod needs our experience and judgement and its efficiency and accuracy is low, so it has already been eliminated. Optical integration is a method which first measure the three stimulus values X, Y, Z, in the wavelength range calculate the Chromaticity Coordinate and other parameters. It is used for low accuracy field. Spectrophotometry need spectral power distribution or the spectrum of the reflected light to calculate the tristimulus values and color parameter.This design collect color using the TCS230 color sensor. There are sixty-four photodiodes and a current-frequency converter on a single chip in this color sensor. It can complete the conversion from light to frequency and from frequency to current. These photodiodes are crosses in the ordered for minimizing the inhomogeneity of the incident light radiation, and increasing the accuracy of color identification. The sixteen photodiodes which have the same color are connected in parallel and distributed in the diode array evenly, so the error of the position of the color can be eliminated. We can select power supply mode by changing the programming pins and scaling factor in two percent,twenty percent or a hundred percent. The design of the output frequency range from 2Hz - 500kHz, the output scale factor make the output of sensor more extensive and is able to adapt to different measurement range. The adaptive capability is raised and the application domain is wider. We use S2 and S3 pin to strobe photodiode array and adjust to blue,green or yellow color filter. We use S0 and S1 pins to adjust the current - frequency converter to select the scale factor make the frequency range 2Hz - 500kHz.We use MCU to handle the current and select AT89S51 for the cost and function. The result is sent to 1602 LCD. We use LCD screen because of its light weight, small size, micro-power, long life, without the advantages of electromagnetic radiation. We need to display characters and numbers and don't need to display Chinese character and graphics. So we choose the low-cost 1602 LCD screen.Keyboard is a critical component in MCU application system. It can transmit to computer input data and command. When we use the keyboard we need to consider the jitter. To take away the jitter we can use the hardware circuit or software delay. This design use a software delay to take away the jitter. When we detect a button is pressed we call a 10ms delay and detect again. If the two judgments of the result is same. The key is closed. If the results are different, it is the jitter. We can use the keyboard interrupt to detect whether the button is pressed. This option would avoid the low efficiency of query mode. We use a three-input AND gate in this design to save microcontroller port and interrupt source.Due to time constraints and my ability, I did't Verificat reliability through lots of experiments. There are also some deficiencies in details. For example, in the selection of light source we can use integrating sphere to get more focused light source. It is helpful for the accuracy. All in all, this device can detect drug fastly and conveniently and is a practical,rapid device for detecting drugs.