Recently, Thies and Urbanski et al. replaced these limited approaches with the pioneering idea of making LoCs fully programmable. In their work, they focus on a new programming language for microfluidics called BioStream.

We further explore the idea of programmable LoCs (PLoCs) and propose a comprehensive instruction set and hardware organization. PLoCs intend to offer the capability of executing a large suite of assays by integrating components that are common to most assays within a set of related domains. An example of a PLoC chip is shown in Figure 1. The chip consists of two main parts: a dry, electronic control part, and a wet fluidic part. The fluidic part integrates: reservoirs for storage, mixers, incubators (reactors), and other fluidic functional units (FFUs) such as capillary electrophoresis separation channels and fluorescence detectors, and optical sensors. These FFUs are interconnected by one or more channels, where the fluid path is defined by opening and closing the appropriate microfluidic valves, and fluid movement is achieved using peristaltic pumps or through other fluid transportation means. The dry part consists of an electronic microcontroller and necessary wiring connections to control the individual microfluidic components (e.g., opening and closing of valves, mixer operation, and incubator temperature). The assay protocol is programmed using an English-like, high-level language and downloaded onto the PLoC controller, similar to software being downloaded on a computer. An example of a programmed assay is shown in Figure 2. The PLoC controller monitors, controls and executes the programmed statements of the assay on the PLoC. Once a PLoC has been designed and tested, the same chip can be used by multiple assays, only requiring the assay user to write a different program for each assay.  This approach results in reduced design/redesign cycles for assay users, and allows them to focus on assay development rather than microfluidic integration. We believe that the PLoC approach may revolutionize microfluidics by enabling versatility, automation and ease of use.

Programmable Lab on a Chip

ploc

Figure 1: A high level diagram of a PLoC

Programmable Lab on a Chip

Labs on a Chip (LoCs) have been used in a multitude of applications, and the US microfluidic industry has matured into a multi-billion dollar industry. The advancement in microfluidic and LoC technology has led to a dramatic increase in the degree of integration of these chips, allowing increasingly larger and more complex chips to be realized. However, LoCs have generally been designed as assay-specific chips (ASC), where microfluidic components are carefully arranged on the chip to map the sequence of operations dictated by the assay protocol. Chip development cycles include significant effort in placement of microfluidic components, prototyping, and testing the new chip for every new assay. Minor modifications to assay specifications typically require similar efforts in redesigning the chip. Such long design cycles result in increased cost and time to market. Further, perhaps a limiting factor to the wide-spread use of LoCs is that the ASC approach requires extensive interaction between the assay user and chip designer, which further hinders productivity. Life scientists must either get sufficient training in microfluidic technology and component design, or must correctly communicate assay requirements to a microfluidic engineer.

This work is supported by the National Science Foundation (NSF) under Grant Numbers CCF-0726821 and CCF-0726694. This work was also supported in part by the Purdue Research Foundation (PRF) and Birck Nanotechnology Center.