Low-tech vs. high-tech approaches in PADs as a result of contrasting needs and capabilities of developed and developing countries focusing on diagnostics and point-of-care testing

Paper-based analysis has captivated scientists' attention in the field of analytical chemistry and related areas for the last two decades. Arguably no other area of modern chemical analysis is so broad and diverse in its approaches spanning from simple 'low-tech' low-cost paper-based analytical devices (PADs) requiring no or simple instrumentation, to sophisticated PADs and microfluidic paper-based analytical devices (mu PADs) featuring elements of modern material science and nanomaterials affording high selectivity and sensitivity. Correspondingly diverse is the applicability, covering resource-limited scenarios on the one hand and most advanced approaches on the other. Herein we offer a view reflecting this diversity in the approaches and types of devices. The core idea of this article rests in dividing mu PADs according to their type into two groups: A) instrumentation-free mu PADs for resource-limited scenarios or developing countries and B) instrumentation-based mu PADs as futuristic POC devices for e-diagnostics mainly aimed at developed countries. Each of those two groups is presented and discussed with the view of the main requirements in the given area, the most common targets, sample types and suitable detection approaches either implementing high-tech elements or low-tech low-cost approaches. Finally, a socioeconomic perspective is offered in discussing the fabrication and operational costs of mu PADs, and, future perspectives are offered.