Acoustofluidic Micromixing Enabled Hybrid Integrated Colorimetric Sensing, for Rapid Point-of-Care Measurement of Salivary Potassium

Abstract

The integration of microfluidics with advanced biosensor technologies offers tremendous advantages such as smaller sample volume requirement and precise handling of samples and reagents, for developing affordable point-of-care testing methodologies that could be used in hospitals for monitoring patients. However, the success and popularity of point-of-care diagnosis lies with the generation of instantaneous and reliable results through in situ tests conducted in a painless, non-invasive manner. This work presents the development of a simple, hybrid integrated optical microfluidic biosensor for rapid detection of analytes in test samples. The proposed biosensor works on the principle of colorimetric optical absorption, wherein samples mixed with suitable chromogenic substrates induce a color change dependent upon the analyte concentration that could then be detected by the absorbance of light in its path length. This optical detection scheme has been hybrid integrated with an acoustofluidic micromixing unit to enable uniform mixing of fluids within the device. As a proof-of-concept, we have demonstrated the real-time application of our biosensor format for the detection of potassium in whole saliva samples. The results show that our lab-on-a-chip technology could provide a useful strategy in biomedical diagnoses for rapid analyte detection towards clinical point-of-care testing applications.

Au@Ag Nanorods‐PDMS Wearable Mouthguard as a Visualized Detection Platform for Screening Dental Caries and Periodontal Diseases

“…The initial surface RI of Au@Ag NRs was 1.400 since they were embedded in PDMS matrix (the RI of PDMS is 1.400). [ 43 ] When the Au@Ag NRs‐PDMS film was exposed to air or water, the surface RI of Au@Ag NRs was unaffected since the RIs of air and water are much smaller than that of PDMS. However, when it was immersed in H 2 S solution, H 2 S molecules diffused into PDMS matrix through nanopores and formed Ag 2 S on the surface of Au@Ag NRs, resulting in a significant increment in surface RI for Au@Ag NRs ($${n_{{\rm{A}}{{\rm{g}}_2}{\rm{S}}}}$$ is ≈2.9).…”

“…The initial surface RI of Au@Ag NRs was 1.400 since they were embedded in PDMS matrix (the RI of PDMS is 1.400). [43] When the Au@Ag NRs-PDMS film was exposed to air or water, the surface Figure 3. Mechanism of the color change of the Au@Ag NRs-PDMS composite to H 2 S. A) Reaction of Ag with H 2 S in air to form Ag 2 S and schematic for the formation of a Ag 2 S layer on the surface of Au@Ag NRs.…”

Survey of Saliva Components and Virus Sensors for Prevention of COVID-19 and Infectious Diseases

“…There are portable [ 30 , 31 , 32 , 33 ] and non portable [ 29 , 34 , 35 , 36 , 37 , 38 ] sensors of salivary glucose reported in the literature. These sensors are based on chemical, electrochemical and optical working principles.…”

Electroosmotic Micromixing in Physicochemically Patterned Microchannels

“…Effective mixing of fluids in microchannels holds significant importance, particularly in drug delivery systems, wherein the drug concentration needs to be precisely controlled for the proper functioning of such systems . Effective mixing can also yield more reliable and precise diagnostic results in point-of-care diagnostics . Microfluidic devices, instrumental in sample preparation and handling, play a crucial role in achieving homogeneous conditions necessary for cell proliferation and nutrition distribution, thus contributing to advancements in tissue engineering applications .…”

“…3 Effective mixing can also yield more reliable and precise diagnostic results in point-of-care diagnostics. 7 preparation and handling, play a crucial role in achieving homogeneous conditions necessary for cell proliferation and nutrition distribution, thus contributing to advancements in tissue engineering applications. 9 Proper mixing is also crucial in high-throughput screening, 12 ensuring rapid processing of samples, and in protein crystallization, 16 where the uniform mixing of precipitant solutions and proteins is important.…”