Osmar, the open-source microsyringe autosampler

Abstract

Microsyringe manipulation is a common approach for the automated sampling of liquids or gases. Commercial devices with this capacity are typically priced above US$30,000, despite their technology being not clearly superior to that commonly found in low-cost (commonly less than US$1,000) devices controlled using G-code (3D printers, CNC routers and laser engravers, for example). Here, we present osmar, an open-source autosampler built by combining parts of two low-cost G-code machines. Movement precision was excellent (error <1% in repeated injections, equivalent to the error reported by the microsyringe manufacturer), and system reliability was comparable to that of commercial models. Also, users do not need extensive knowledge in electronics or advanced computing to make osmar work as an autosampler, because it can easily be integrated with analytical instruments using AutoIt, a scripting language for the Windows Operating System. Therefore, osmar is a viable, low-cost, and technically-accessible alternative for automated sampling with microsyringes, and can be also adapted and expanded for more general liquid handling tasks.