Integration of field effect transistor-based biosensors with a digital microfluidic device for a lab-on-a-chip application

Abstract

A new platform for lab-on-a-chip system is suggested that utilizes a biosensor array embedded in a digital microfluidic device. With field effect transistor (FET)-based biosensors embedded in the middle of droplet-driving electrodes, the proposed digital microfluidic device can electrically detect avian influenza antibody (anti-AI) in real time by tracing the drain current of the FET-based biosensor without a labeling process. Digitized transport of a target droplet enclosing anti-AI from an inlet to the embedded sensor is enabled by the actuation of electrowetting-on-dielectrics (EWOD). A reduction of the drain current is observed when the target droplet is merged with a pre-existing droplet on the embedded sensor. This reduction of the drain current is attributed to the specific binding of the antigen and the antibody of the AI. The proposed hybrid device consisting of the FET-based sensor and an EWOD device, built on a coplanar substrate by monolithic integration, is fully compatible with current fabrication technology for control and read-out circuitry. Such a completely electrical manner of inducing the transport of bio-molecules, the detection of bio-molecules, the recording of signals, signal processing, and the data transmission process does not require a pump, a fluidic channel, or a bulky transducer. Thus, the proposed platform can contribute to the construction of an all-in-one chip.

A Versatile Automated Platform for Micro-scale Cell Stimulation Experiments

“…Figure 3); use of flat-surfaced (rather than rounded) microcapillaries for the perfusion chamber module would facilitate this type of analysis. Additionally, cells can be imaged on the DMF hub 14,15 …”

“…2. Using metal compression frames, fix the DMF plates into a polymer cast 14,30 with recesses that maintain a 400 μm spacing between the plates; this spacing, combined with the actuation electrode size (2.5 mm each to extend to the edge of its cognate actuation electrode. 4.…”

“…As described previously 14,29 , pattern the bottom plate of the DMF device with forty-six indium tin oxide (ITO) electrodes (drivers of droplet actuation) by photolithography and etching, and coat with 5 μm of Parylene-C and 50 nm of Teflon-AF. Form the top plate of the DMF device by coating an unpatterned ITO glass substrate with Teflon-AF, as above.…”

“…The platform architecture (Figure 1) is modular in design: a set of fibronectin-coated microcapillaries ("cell perfusion chambers" module) serves as the site for establishment, maintenance, and stimulation of micro-scale cultures; and a digital microfluidics (DMF) 12,13 device outfitted with "transfer" microcapillaries ("central hub" module) 14,15 routes cells and reagents to and from the perfusion chambers. DMF enables the user to individually address multiple droplets simultaneously and to change or re-order the manipulations (i.e.…”

Medical Devices Development: The Bottom-Up or The Top-Down Approach?

“…As explained in reference [11], the idea of using microfabrication techniques is to reduce the volume of the biological sample under analysis. Indeed, different microfluidic principles are described together with examples of applications involving immunoassays among others [12][13][14]. It is explained that the smallest sample volumes can be achieved using digital microfluidics.…”