Nanowire sensors monitor bacterial growth kinetics and response to antibiotics

Miniaturized and cost-efficient methods aiming at high throughput analysis of microbes are of great importance for the surveillance and control of infectious diseases and the related issue of antimicrobial resistance. Here we demonstrate a miniature nanosensor based on a honeycomb-patterned silicon nanowire field effect transistor (FET) capable of detection of bacterial growth and antibiotic response in microbiologically relevant nutrient media. We determine the growth kinetics and metabolic state of Escherichia coli cells in undiluted media via the quantification of changes in the source-drain current caused by varying pH values. Furthermore, by measuring the time dependent profile of pH change for bacterial cultures treated with antibiotics, we demonstrate for the first time the possibility of electrically distinguishing between bacteriostatic and bactericidal drug effects. We believe that the use of such nanoscopic FET devices enables addressing parameters that are not easily accessible by conventional optical methods in a label-free format, i.e. monitoring of microbial metabolic activity or stress response.

Microfluidic alignment and trapping of 1D nanostructures – a simple fabrication route for single-nanowire field effect transistors

Microfluidic trapping of 1D nanostructures at predefined positions for subsequent facile contacting via UV-lithography.

A simple two-step silane-based (bio-) receptor molecule immobilization without additional binding site passivation

Immobilizing (bio-) receptor molecules via 3-(triethoxysilyl)propylsuccinic anhydride makes subsequent binding site blocking dispensable, while maintaining receptor specificity for target analytes.

Multifunctional reversibly sealable microfluidic devices for patterned material deposition approaches

We present reversibly sealable microfluidic devices with versatile channel designs, withstanding pressures up to 600 kPa, which can be applied for direct printing of electronic interconnects on flexible surfaces as well as micropatterning the UV curable materials.

Copper nanowire synthesis by directed electrochemical nanowire assembly

The growth of high aspect ratio copper nanowires with lengths of up to several micrometers and diameters of about 100 nm via directed electrochemical nanowire assembly (DENA) is presented.

Characterization of magnetic colloids by means of magnetooptics

A new, efficient method for the characterization of magnetic colloids based on the Faraday effect is proposed. According to the main principles of this technique, it is possible to detect the stray magnetic field of the colloidal particles induced inside the magnetooptical layer. The magnetic properties of individual particles can be determined providing measurements in a wide range of magnetic fields. The magnetization curves of capped colloids and paramagnetic colloids were measured by means of the proposed approach. The registration of the magnetooptical signals from each colloidal particle in an ensemble permits the use of this technique for testing the magnetic monodispersity of colloidal suspensions.