Lab-on-a Chip platforms for manipulation and sensing of biological entities

The advent and continuous scaling of micro-fabrication technology has offered new capabilities in realization of Lab-on-a-Chip (LoC) platforms. More specifically, they offer the potential to perform spatial control and manipulation of biological targets with embedded transducers to sense and process them. If such platforms can be integrated transistors and readout circuitry, it has the potential to offer truly miniaturized solution. From a standpoint of LoC platform design, we present two platforms for biosensing and manipulation of cells.;First, I present a CMOS LoC platform for DEP trapping and repositioning of cells and microorganisms. Given the need to perform the operation in real-time, in-situ impedance monitoring of the trapping function is demonstrated. We present EM simulation results for DEP force and reorientation by novel three-dimensional (3D) octapole electrode geometry, all realized in a commercial 0.5mum CMOS process. This CMOS LoC platform integrates an analog front end for impedance monitoring of biological targets as they are repositioned on electrodes due to DEP in real-time. Experimental results with yeast cells validate the design.;Second, I present a compact AC susceptometer for biosensing based on Brownian relaxation of magnetic nanoparticle (MNP). A novel multiplexed sensing scheme based on the measurement of the magnetic susceptibility of the affinity captured target molecules on magnetic nanoparticles in liquid suspension is proposed. The AC magnetic susceptibility provides a measurement of Brownian relaxation behavior of biomolecules bound to MNPs that is related to its hydrodynamic size. The miniaturized AC susceptometer exhibits high sensitivity in magnetic fields as low as 10 muT for 1 mg ml--1 concentration and 5 mul volume, and is fully software programmable. The capability of biological sensing using the proposed scheme has been demonstrated in proof of principle using the binding of biotinylated horseradish peroxidase (HRP) to streptavidin-coated MNPs. The technique and instrument are readily compatible with lab-on-chip applications for point-of-care medical applications.