Development of Low-Cost Remote Control Photometer for Solution Concentration Determination

摘要

Researchers usually use spectrophotometers to analyze the compositions of the unknown solution and estimate the concentration according to its light absorbance. Although spectrophotometers could provide a wide range of spectrum for "spectro-scanning" purposes, most spectrophotometers were not suitable for outdoor measurements and expensive because of elaborate optical components. For some biochemical inspection or clinical analysis applications, only a few specific wavelengths of light are applied to examine the light absorbance of ascertaining chemical analyte regularly. The light emitting diode (LED) is a kind of superior light source that brings an excellent monochromatic light beam profile and delivers wavelengths from ultraviolet to near infrared. In this work, a low-cost and remote control photometer is developed by use of the LED. Four different wavelengths of LEDs are installed inside the photometer as the inspecting light directly to substitute for the complicated diffraction grids or the delicate optical components to low down the cost of the photometer. These four LEDs are collimated by a single collimator lens to make all the light beams be able to irradiate the analyte entirely in the cuvette. Each time only one LED can be switched on, according to the wavelength requirements of the inspections. The proposed photometer is controlled by personal handheld devices, such as smartphones and tablets that are equipped the exclusive application program (APP). The APP is designated to communicate with the photometer via the interface of Bluetooth Low Energy protocol (BLE). The photometer establishes the excellent linearity relationship between sample concentrations and their absorbance in the testing experiments. As a result, the low cost photometer proves itself to determine the concentration of the sample preliminarily for industrial inspections as well as to be basic tutorial equipment in laboratory courses.