Capillary-driven toner-based microfluidic devices for clinical diagnostics with colorimetric detection.

The fabrication of toner-based microfluidic devices to perform clinical diagnostics with capillary action and colorimetric detection is described in this report. Test zones and microfluidic channels were drawn in a graphic software package and laser printed on a polyester film. The printed layout and its mirror image were aligned with an intermediary cut-through polyester film and then thermally laminated together at 150 °C at 60 cm/min to obtain a channel with ca. 100-µm depth. Colorimetric assays for glucose, protein, and cholesterol were successfully performed using a desktop scanner. The limit of detection (LD) values found for protein, cholesterol, and glucose were 8, 0.2, and 0.3 mg/mL, respectively. The relative standard deviation (RSD) values for an interdevices comparison were 6%, 1%, and 3% for protein, cholesterol, and glucose, respectively. Bioassays were successfully performed on toner-based devices stored at different temperatures during five consecutive days without loss of activity.

Microfluidic toner-based analytical devices: disposable, lightweight, and portable platforms for point-of-care diagnostics with colorimetric detection.

This chapter describes the development of microfluidic toner-based analytical devices (µTADs) to perform clinical diagnostics using a scanner or cell-phone camera. µTADs have been produced in a platform composed of polyester and toner by the direct-printing technology (DPT) in a matter of minutes. This technology offers simplicity and versatility, and it does not require any sophisticated instrumentation. Toner-based devices integrate the current generation of disposable analytical devices along paper-based chips. The cost of one µTAD has been estimated to be lower than $0.10. In addition, these platforms are lightweight and portable thus enabling their use for point-of-care applications. In the last 5 years, great efforts have been dedicated to spread out the use of µTADs in bioassays. The current chapter reports the fabrication of printed microplates and integrated microfluidic toner-based devices for dengue diagnostics and rapid colorimetric assays with clinically relevant analytes including cholesterol, triglycerides, total proteins, and glucose. The use of µTADs associated with cell-phone camera may contribute to the health care, in special, to people housed in developing regions or with limited access to clinics and hospitals.