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Abstract

A CMOS digital ROIC is presented for multi-channel and differential piezo-resistive sensing, as part of the positioning system of a liquid dispensing MEMS. New very low-voltage and single-battery compatible circuit techniques are proposed for digital gain tuning, pre-amplification and A/D conversion. Also, overall low-power consumption is achieved by operating key devices in subthreshold to prevent from heating the fluidic MEMS. The complete system has been integrated in 0.35 mum CMOS 2-polySi 4-metal technology.

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Abstract

Electro-osmotic flows are used to actuate the surrounding fluid and bring particles in the solution at the proximity of a biosensor surface. This phenomenon allows the local increase in particle number and should decrease the biosensors response time. To predict concentration rate and efficiency, we compute the electric field and the flow velocity above the electrodes. Spectral collocation is used to solve the electrical and fluidic governing equations of the phenomenon. Theoretical results are proposed and experimental measurements are compared with the calculations.

Abstract

Most of review articles or even books dedicated to biosensing issues are organized by the generally admitted scheme of a biosensor. Subsequently, biological receptors, modified surfaces (and ways to specifically modify those surfaces using established biological and/or chemical recipes) and transduction techniques are thoroughly addressed in this precise order. In this review, we deliberately decided to break the conventional way of providing biosensing review by uniquely addressing biomolecules immobilization methods onto a solid surface and biosensing-related transduction techniques. The aim of this review is to provide a contemporary snapshot of the biosensing landscape without neglecting the seminal references or products where needed. The main guiding line of the review is the downscaling (from the macro- to the nanoscale) of biosensors and their respective most known applications. To conclude, a brief overview of the most popularized nanodevices applied to biology is given before attempting to comment on biosensors comparison criteria in terms of targeted applications.

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This work reports the combination of liquid contact deposition using a MEMs system on interdigitated nanoelectrode devices. Our methodology and tools allows the deposition of different biological solutions on 103 nanoelectrode devices in less than one hour on a 4 inch wafer.

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For the purpose of biochip miniaturization, we developed a liquid spotter-based on silicon microcantilevers incorporating in-plane nanotips as a MEMS nanopatterning tool. We present new fabricated cantilevers with added piezoresistors for the contact force control during deposition. Matrices of droplets of 1 ¼m in diameter were achieved with a 10 ¼m interspot distance with high uniformity and high reproducibility by the nanotip cantilever with piezoresistive force controller.

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The methods presented can be used for non-photostructurable polymers and where spin-coating cannot be performed. As demonstrator of the viability of the proposed fabrication process, they have been applied for the definition of hydrophobic barriers on a microfluidics network, which is dedicated to selectively dispense liquid to a spotting device consisting of 12 silicon microcantilevers.

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