Improving quantitative control and homogeneous distribution of sample on paper-based analytical devices via drop-on-demand inkjet printing
The standard desktop printer with multiple ink cartridges can accurately deposit a broad variety of biomaterials on microfluidic paper-based analytical devices (μPADs) which have been extensively applied to environmental monitoring, screening for food and beverage contamination. How to realize sample quantitative control by tuning CMYK value, however, remains challenging. Herein, we studied the influence of CMYK value on ink volume jetted by ink cartridges. The regularity research on single-color and two-color was performed in two print mode-grayscale printing and color printing. The results demonstrated that the number of ink dots increased with the increase of gray value and opacity value, which means the amount of bio-ink enhances with the increase of CMYK value. The 3, 3’, 5,5’-tetramethylbenzidine - horseradish peroxidase - hydrogen peroxide, glucose oxidase - horseradish peroxidase and bull serum albumin - citrate buffer - tetrabromophenol blue system were chosen as examples to prove the print regularity. Samples and assay reagents can be quantitatively deposited on substrate by adjusting CMYK value with as many as four ink cartridges. The present approach has been successfully applied to assay the targets in real serum samples, showing the potential application of the most common office piezoelectric printer in μPADs.