Optofluidic marine phosphate detection with enhanced absorption using a Fabry–Pérot resonator

Abstract

Real-time detection of phosphate has significant meaning in marine environmental monitoring and forecasting the occurrence of harmful algal blooms. Conventional monitoring instruments are dependent on artificial sampling and laboratory analysis. They have various shortcomings for real-time applications because of the large equipment size and high production cost, with low target selectivity and the requirement of time-consuming procedures to obtain the detection results. We propose an optofluidic miniaturized analysis chip combined with micro-resonators to achieve real-time phosphate detection. The quantitative water-soluble components are controlled by the flow rate of the phosphate solution, chromogenic agent A (ascorbic acid solution) and chromogenic agent B (12% ammonium molybdate solution, 80% concentrated sulfuric acid and 8% antimony potassium tartrate solution with a volume ratio of 80 : 18 : 2). Subsequently, an on-chip Fabry-Pérot microcavity is formed with a pair of aligned coated fiber facets. With the help of optical feedback, the absorption of phosphate can be enhanced, which can avoid the disadvantages of the macroscale absorption cells in traditional instruments. It can also overcome the difficulties of traditional instruments in terms of size, parallel processing of numerous samples and real-time monitoring, etc. The absorption cell length is shortened to 300 μm with a detection limit of 0.1 μmol L. The time required for detection is shortened from 20 min to 6 seconds. Predictably, microsensors based on optofluidic technology will have potential in the field of marine environmental monitoring.

An Integrated Optofluidic Platform Enabling Total Phosphorus On-Chip Digestion and Online Real-Time Detection

“…When measuring the phosphate in water, the phosphate is usually converted into PMo heteropoly blue by the chromogenic reaction, which has a strong characteristic absorption peak at about 890 nm [5]. First, the light source used for the detection is calibrated and measured by spectrometer.…”

“…Thus, the effect of temperature was investigated in the experiment. A miniheater was placed under spiral microchannel of the digestion to adjust the reaction temperature, and the different typical phosphates solution samples including inorganic phosphate and organic phosphate with the same concentration of 0.3 mg/L (by weight of P) were prepared and pumped into the optofluidic device with the flow rate of 50 µL/min [5]. Meanwhile, the concentration of K 2 SO 4 was prepared as 50 g/L and the flow rate of K 2 SO 4 and chromogenic agent A and B was set as 15 µL/min.…”

“…The traditional digestion time of several hours is greatly reduced to less than 10 s, and the content of total phosphorus can be obtained in a few minutes. The integrated optofluidic device can significantly shorten the test time and reduce the sample amount, and also provides a versatile platform for the real-time detection and analysis of many biochemical samples.Micromachines 2020, 11, 59 2 of 12 so on [4,5]. Here, as one of the most popular optical methods, UV-visible (UV-Vis) spectrophotometry has been employed for the Chinese national standard method (Water-Quality-Determination of total phosphorus-ammonium molybdate spectrophotometric method (GB 11893-89)) because of its simple detection mechanism [6].…”

“…Micromachines 2020, 11, 59 2 of 12 so on [4,5]. Here, as one of the most popular optical methods, UV-visible (UV-Vis) spectrophotometry has been employed for the Chinese national standard method (Water-Quality-Determination of total phosphorus-ammonium molybdate spectrophotometric method (GB 11893-89)) because of its simple detection mechanism [6].…”

Silver Nanoprism Enhanced Colorimetry for Precise Detection of Dissolved Oxygen

“…This new field provides lots of unique advantages for enhancing the performance and simplifying the design of micro-electromechanical systems [17]. Over the past decades, this new field has been developing rapidly, and it has been applied in many areas such as biosensor [18], water purification [19], optical devices [20,21] and water sensing [22]. Nowadays, the field of soft optical materials has received wide attention [23].…”