Paperfuge: An ultra-low cost, hand-powered centrifuge inspired by the mechanics of a whirligig toy

Abstract

One sentence summary: By uncovering the dynamics of a classical toy, we invent a paper-based, low-cost (20 cents) centrifuge, capable of 125,000 rpm, using only hand-power. 1All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/072207 doi: bioRxiv preprint first posted online Abstract Sample preparation, including separation of plasma from whole blood or isolation of parasites, is an unmet challenge in many point of care (POC) diagnostics and requires centrifugation as the first key step. From the context of global health applications, commercial centrifuges are expensive, bulky and electricity-powered, leading to a critical bottle-neck in the development of decentralized, electricity-free POC diagnostic devices. By uncovering the fundamental mechanics of an ancient whirligig toy (3300 B.C.E), we design an ultra-low cost (20 cents), light-weight (2 g), human-powered centrifuge that is made out of paper ("paperfuge").To push the operating limits of this unconventional centrifuge, we present an experimentallyvalidated theoretical model that describes the paperfuge as a non-linear, non-conservative oscillator system. We use this model to inform our design process, achieving speeds of 125,000 rpm and equivalent centrifugal forces of 30,000 g, with theoretical limits predicting one million rpm. We harness these speeds to separate pure plasma in less than 1.5 minutes and isolate malaria parasites in 15 minutes from whole human blood. By expanding the materials used, we implement centrifugal microfluidics using PDMS, plastic and 3D-printed devices, ultimately opening up new opportunities for electricity-free POC diagnostics, especially in resource-poor settings.

Mobilefuge: A low-cost, portable, open source, 3D-printed centrifuge that can be used for purification of saliva samples for SARS-CoV2 detection

“…S1 (a) allows to step up the standard 5V output from USB ports to 12V continuously, without requiring any soldering of parts. Such a step up of the voltage helps to achieve higher RPMs which will be quite useful for applications like separation of plasma from blood to diagnose malaria [24].…”

“…Therefore, scientists and hobbyists exploited a variety of existing rotary mechanisms in consumer devices and toys to build centrifuges. These highly creative designs involve either a hand powered rotary mechanism in hand crank torch lights [11], fidget spinners [22], [23], toys [24], [25], salad spinners [26], [27], egg beaters [28] or electric motor powered rotary mechanism in consumer electronic devices such as drones [29], [30], [31], [32], [33], [34] [35], [36], computer fans [37], hard disks [38], DVD drives [39] and Dremel tools [40]. Proliferation of low-cost digital fabrication methods such as 3D printers [22], [40], CNC machines [33] and laser cutters [11], [32], [38] helped to bring the best out of these designs by providing a safety enclosure and customisable rotor for various centrifuge tubes.…”

Diagnostic Devices with Microfluidics

“…Power requirements: In the United States, there is much speculation that a manual centrifuge is better than a battery-powered centrifuge in lowresource settings (Brown et al 2011;Saad Bhamla et al 2016;Wong et al 2008). The reasoning put forward is that electrical power is unreliable and batteries are not easily available, so power-free options are required.…”

Portable sequencing as a teaching tool in conservation and biodiversity research

“…PCR machines (e.g., MiniPCR, MiniOne; range US$650-US$900) that can be controlled by smartphones and run from simple battery packs, have been field-tested [7]. Small desktop centrifuges, with either a fixed or variable speed, are available from multiple vendors (cost US$150-US$350), but it is even possible to 3D print a manually powered do-it-yourself centrifuge (e.g., the paperfuge [10]). All costs listed were sourced at the time of publication.…”