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. 2014 Dec 30;15(1):547–564. doi: 10.3390/s150100547

Table 2.

Important criteria for sample preparation processes considerations for the development of electrochemical (micro) sensors.

Criteria Specific to Electrochemical Sensors Examples Additional Important Criteria and Those Specific to Microfluidic Electrochemical Sensors Examples
Removal of electrochemically active compounds

  • In serum/plasma [31]:

    • -

      Uric acid

    • -

      Ascorbic acid

    • -

      Dopamine

    • -

      L-cysteine

    • -

      Acetaminophen

    • -

      Salicylic acid

  • In urine [32]:

    • -

      Urea

    • -

      Tartaric acid

    • -

      Citric acid

    • -

      Glucose

    • -

      Leucine

    • -

      Proline

    • -

      Tyrosine

  • In saliva [33]:

    • -

      Uric acid

    • -

      Ascorbic acid

 Removal of particulate to avoid clogging of microchannels and microvalves [34] Blood cells may form aggregates clogging the microchannels during separation of plasma from blood [35]
Adjustment of ionic strength and temperature [36,37]
  • -

    Variable ionic strength influence potentiometric, conductimetric and also voltammetric measurements. In addition, ionic strength and nature affects biological reactions [36]

  • -

    Temperature affects the slope of the electrode response according to the Nernst equation [37]

 Reducing non specific absorption of hydrophobic material such as PDMS [38] Adsorption of fluorescence markers can cause a drift in the background fluorescence intensity [38]
Removal of surface fouling compounds [39] Fouling cause by plasma proteins, lipids, and other biochemical components of the biological fluids [39] Removal of compounds interfering with the biorecognition or signal amplification mechanisms [40] PCR inhibitors in blood sample such as heme, hemoglobin, lactoferrin and immunoglobulin G [40]
Adjustment of pH [41] A pH buffer can be used to reduce hydroxyl ion (OH−) effects that interfere ISE electrodes [41] Adjustment of pH [42] Surface charge (Zeta potential) of the microchannels' walls is generally a function of the pH thus, the electroosmotic pumping process can be enhanced or degraded by changes in pH [42]