Various nanowire or nanotube-based devices have been demonstrated to fulfill the anticipated future demands on sensors. To fabricate such devices, electric field-based methods have demonstrated a great potential to integrate one-dimensional nanostructures into various forms. This review paper discusses theoretical and experimental aspects of the working principles, the assembled structures, and the unique functions associated with electric field-based assembly. The challenges and opportunities of the assembly methods are addressed in conjunction with future directions toward high performance sensors.

A disposable cable-shaped flexible battery is presented using a simple, low cost manufacturing process. The working principle of an aluminum–air galvanic cell is used for the cable-shaped battery to power portable and point-of-care medical devices. The battery is catalyzed with a carbon nanotube (CNT)-paper matrix. A scalable manufacturing process using a lathe is developed to wrap a paper layer and a CNT-paper matrix on an aluminum wire. The matrix is then wrapped with a silver-plated copper wire to form the battery cell. The battery is activated through absorption of electrolytes including phosphate-buffered saline, NaOH, urine, saliva, and blood into the CNT-paper matrix. The maximum electric power using a 10 mm-long battery cell is over 1.5 mW. As a demonstration, an LED is powered using two groups of four batteries in parallel connected in series. Considering the material composition and the cable-shaped configuration, the battery is fully disposable, flexible, and potentially compatible with portable biosensors through activation by either reagents or biological fluids.

Rapid, low cost screening of tuberculosis requires an effective enrichment method of Mycobacterium tuberculosis (MTB) cells. Currently, microfiltration and centrifugation steps are frequently used for sample preparation, which are cumbersome and time-consuming. In this study, the size-selective capturing mechanism of a microtip-sensor is presented to directly enrich MTB cells from a sample mixture. When a microtip is withdrawn from a spherical suspension in the radial direction, the cells that are concentrated by AC electroosmosis are selectively enriched to the tip due to capillary- and viscous forces. The size-selectivity is characterized by using polystyrene microspheres, which is then applied to size-selective capture of MTB from a sample mixture. Our approach yields a detection limit of 800 cells mL(-1), one of the highest-sensitivity immunosensors to date.

PCR inhibitory substances in complex sample matrices can cause false negatives or underestimation of target concentration. This study assessed DNA heat treatment for reducing inhibition during qPCR analysis of human adenovirus (HAdV) in wastewater samples. Inhibition was reduced by heat treating DNA, where mean HAdV concentration was increased by 0.71 log 10 GC/L (and up to 3.04 log 10 GC/L in one case), and replicate variability and false negatives were reduced. DNA heat treatment should be further investigated for improving reliability of HAdV concentration estimates in water, which can support more accurate assessment of health risks associated with viral pathogen exposure.