A Phosphorescence Quenching-Based Intelligent Dissolved Oxygen Sensor on an Optofluidic Platform

Abstract

Continuous measurement of dissolved oxygen (DO) is essential for water quality monitoring and biomedical applications. Here, a phosphorescence quenching-based intelligent dissolved oxygen sensor on an optofluidic platform for continuous measurement of dissolved oxygen is presented. A high sensitivity dissolved oxygen-sensing membrane was prepared by coating the phosphorescence indicator of platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) on the surface of the microfluidic channels composed of polydimethylsiloxane (PDMS) microstructure arrays. Then, oxygen could be determined by its quenching effect on the phosphorescence, according to Stern–Volmer model. The intelligent sensor abandons complicated optical or electrical design and uses a photomultiplier (PMT) counter in cooperation with a mobile phone application program to measure phosphorescence intensity, so as to realize continuous, intelligent and real-time dissolved oxygen analysis. Owing to the combination of the microfluidic-based highly sensitive oxygen sensing membrane with a reliable phosphorescent intensity detection module, the intelligent sensor achieves a low limit of detection (LOD) of 0.01 mg/L, a high sensitivity of 16.9 and a short response time (22 s). Different natural water samples were successfully analyzed using the intelligent sensor, and results demonstrated that the sensor features a high accuracy. The sensor combines the oxygen sensing mechanism with optofluidics and electronics, providing a miniaturized and intelligent detection platform for practical oxygen analysis in different application fields.

Development of Dissolved Oxygen Sensor Based on Time‐domain Lifetime Measurement with a Sensing Film Fabricated by Embedding PtOEP in Highly Stable and Highly Hydrophobic Fluorinated Matrix

“…Our dissolved oxygen sensor had a moderate response time of 30 s and recovery time of 180 s. These times were longer than the response time of 22 s and recovery time of 94 s for a microfluidic system [31] . The fast response time can be explained by the thinner sensing membrane used in the microfluidic system thus the shorter distance that the oxygen molecules needed to permeate.…”

“…In our sensor, the cheap, compact and low‐power consuming photodiode was used to detect the fluorescence signal, therefore, our sensor had a good balance between accuracy and cost. For comparison, the typical response time of commercially available dissolved oxygen sensors based on fluorescence quenching varied from a few seconds to about 150 s [2,31] …”

Well-Designed Smartphone-Based Imaging Biosensor

“…The resolution of smartphoneembedded CMOS image sensor (CIS) cameras now exceeds 20 million pixels, and the pixel pitch has been reduced to about 1 μm. Recently, smartphone optical sensors using this high pixel density have been extensively used for bioimaging medical diagnosis in microfluidics [2][3][4][5][6][7][8][9][10][11]. For example, an optical fiber surface plasmon resonance (SPR) sensor system was reported by Bremer et al They used the flash and camera on the back of a smartphone to excite and interrogate the SPR sensor system [12].…”

Microfluidic-Based Oxygen (O2) Sensors for On-Chip Monitoring of Cell, Tissue and Organ Metabolism

“…In another development, Wang and colleagues developed a portable detector for O 2 detection using a PDMS chip and a PtTFPP film [ 79 , 80 ]. The detector ( Figure 3 C), comprised of a photomultiplier (PMT) counter (with a Charge Coupled Device (CCD) camera and an imaging spectrograph) connected to a smart-phone application and was able to detect DO levels with an LOD of 0.01 mg/L (0.37 µM) and short response time of 22 s. The simplicity, low-cost production, handling of the device, high sensitivity, short response time and portability are among important features which make this detector a desirable device for on-chip O 2 sensing, especially in medical applications.…”

“…( C ) A portable handheld photodetector device connected to a mobile app for chip-based O 2 monitoring. Reproduced with permission [ 80 ], copyright 2021, MDPI.…”