Modern microfluidic approaches for determination of ions

Lab-on-a-chip technology has enabled the development of disruptive detection and analysis methods for life sciences and beyond. The miniaturization of existing (and sometimes well established) analysis techniques within microfluidic devices has the potential of resulting in the development of inexpensive, user-friendly and portable devices. This has been the case with ions detection from liquid samples, including water or biological samples like urine, blood and sweat, to name a few. We provide a critical review on recent microfluidic approaches for measurement of ions using microfluidic devices, covering sample treatment (pre-concentration and separation), various ion chelating mechanisms (immunoassay, nucleic acid and chemical chelating) and varying ion detection strategies (optical, electrochemical and colorimetric). It identified areas of development and opportunities mostly in water quality and environment monitoring but also in healthcare diagnostic testing, including detection with smartphones and wearable microfluidic devices.