Polysilicon nanowire biosensors have been fabricated using a top-down process and were used to determine the binding constant of two inflammatory biomarkers. A very low cost nanofabrication process was developed, based on simple and mature photolithography, thin film technology, and plasma etching, enabling an easy route to mass manufacture. Antibody-functionalized nanowire sensors were used to detect the proteins interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) over a wide range of concentrations, demonstrating excellent sensitivity and selectivity, exemplified by a detection sensitivity of 10 fM in the presence of a 100 000-fold excess of a nontarget protein. Nanowire titration curves gave antibody−antigen dissociation constants in good agreement with low-salt enzyme-linked immunosorbent assays (ELISAs). This fabrication process produces high-quality nanowires that are suitable for low-cost mass production, providing a realistic route to the realization of disposable nanoelectronic point-of-care (PoC) devices.

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Abstract-Biosensors are commonly produced using an SOI CMOS process and advanced lithography to define nanowires. In this work, a simpler and cheaper junctionless 3-mask process is investigated, which uses thin film technology to avoid the use of SOI wafers, in-situ doping to avoid the need for ion implantation and direct contact to a low doped polysilicon film to eliminate the requirement for heavily doped source/drain contacts. Furthermore, TiN is used to contact the biosensor source/drain because it is a hard, resilient material that allows the biosensor chip to be directly connected to a printed circuit board without wire bonding. pH sensing experiments, combined with device modelling, are used to investigate the effects of contact and series resistance on the biosensor performance, as this is a key issue when contacting directly to low doped silicon. It is shown that in-situ phosphorus doping concentrations in the range 4×10

Silicon nanowires are label-free sensors that allow real-time measurements. They are economical and pave the road for point-of-care applications but require complex readout and skilled personnel. We propose a new model and technique for sensing nanowire sensors using alternating currents (AC) to capture both magnitude and phase information from the sensor. This approach combines the advantages of complex impedance spectroscopy with the noise reduction performances of lock-in techniques. Experimental results show how modifications of the sensors with different surface chemistries lead to the same direct-current (DC) response but can be discerned using the AC approach.

We present the structure of an open microwell, i.e. a microwell open at both the top and bottom ends, which enables single-cells to be handled, processed and recovered after the experiment. The microwell has a novel architecture which allows particles to be trapped and forced to interact by means of a cylindrical negative dielectrophoretic cage. Particles are aligned along a horizontal axis where the electric field minimum is placed. Arrays of open microwells are fabricated using flexible printed circuit board (PCB) technology providing cheap and disposable devices. Levitation and precise positioning of both polystyrene beads and K562 cells were experimented, confirming the results of physical simulations. Assessment of cell viability after 20 min exposure to the electric field was performed through a standard calcein-release assay.