1.2. The Presented Work
The work presented at the 4th Microfluidic Handling Systems conference and which is extended in this paper aims at the development of a disposable, polymer-based DNA amplification lab-on-chip system with integrated resistive heater based on the World Health Organization (WHO) Sexually Transmitted Diseases Diagnostics Initiative (SDI) ASSURED criteria. Devices which are ASSURED are (A) affordable, (S) sensitive, (S) specific, (U) user-friendly, (R) robust and rapid, (E) equipment-free, and (D) deliverable to those who need them [20,49]. The first step towards such a device is the development of the chip itself. This paper focuses on the choice of substrate material, metal deposition method, and type of metal. Although, it is mentioned above that PCR and HDA are sequence specific, the reaction chosen is the isothermal multiple displacement amplification (MDA) [50]. This reaction is more straightforward [51], as it amplifies any present DNA, and is therefore better suitable as a proof-of-principle amplification reaction to show the functioning of the integrated heater and the biocompatibility of the substrate after the fabrication process. The use of an isothermal amplification technique also simplifies the final device and lowers its footprint, as there are no pumps required. In this research, external analysis methods are used which do not contribute to the WHO-SDI ASSURED criteria due to their bulkiness, costs, and difficulty. However, suggestions and comments on the integration of low-cost detection methods, which are ASSURED, are given in Section 5.