A passive flow microreactor for urine creatinine test.

Area of Science:

• Biomarker detection and microfluidics
• Point-of-care diagnostics for chronic kidney disease (CKD)

Background:

• Chronic kidney disease (CKD) poses a significant global health and economic burden.
• Current CKD diagnostic methods rely on lab-based tests for biomarkers like creatinine.
• Existing tests are regulated and lack point-of-care (PoC) accessibility for routine monitoring.

Purpose of the Study:

• To develop a passive flow microreactor for colorimetric urine creatinine measurement (uCR-Chip).
• To create a PoC assay for CKD assessment by integrating with a microfluidic urine albumin assay.
• To enable rapid, accurate, and accessible CKD biomarker quantification.

Main Methods:

• Developed a passive flow microreactor (uCR-Chip) utilizing a 2-phase pressure compensation (2-PPC) technique.
• Employed microfluidic channel network design and an optimized observation window (OW) for fluidic control and signal stability.
• Utilized custom photomask production and dry-film photoresist lithography for precise chip fabrication; detection via USB microscope platform.

Main Results:

• Achieved a uniform and stable detection signal within 7 minutes.
• Demonstrated a dynamic linear detection range up to 40 mM with a lower limit of detection (LOD) of 0.521 mM.
• Validated the assay with artificial urine, showing acceptable recovery and low matrix effects, comparable to commercial PoC systems.

Conclusions:

• The developed uCR-Chip offers a viable PoC test for chronic kidney disease (CKD) assessment.
• The microreactor provides accurate creatinine quantification, meeting clinical precision requirements.
• This technology platform has potential for measuring various disease biomarkers at the point of care.