Bergoi Ibarlucea

Light Weight and Flexible High‐Performance Diagnostic Platform

A flexible diagnostic platform is realized and its performance is demonstrated for early detection of avian influenza virus (AIV) subtype H1N1 DNA sequences. The key component of the platform is high-performance biosensors based on high output currents and low power dissipation Si nanowire field effect transistors (SiNW-FETs) fabricated on flexible 100 μm thick polyimide foils. The devices on a polymeric support are about ten times lighter compared to their rigid counterparts on Si wafers and can be prepared on large areas. While the latter potentially allows reducing the fabrication costs per device, the former makes them cost efficient for high-volume delivery to medical institutions in, e.g., developing countries. The flexible devices withstand bending down to a 7.5 mm radius and do not degrade in performance even after 1000 consecutive bending cycles. In addition to these remarkable mechanical properties, on the analytic side, the diagnostic platform allows fast detection of specific DNA sequences of AIV subtype H1N1 with a limit of detection of 40 × 10(-12) m within 30 min suggesting its suitability for early stage disease diagnosis.

High-Performance Three-Dimensional Tubular Nanomembrane Sensor for DNA Detection

We report an ultrasensitive label-free DNA biosensor with fully on-chip integrated rolled-up nanomembrane electrodes. The hybridization of complementary DNA strands (avian influenza virus subtype H1N1) is selectively detected down to attomolar concentrations, an unprecedented level for miniaturized sensors without amplification. Impedimetric DNA detection with such a rolled-up biosensor shows 4 orders of magnitude sensitivity improvement over its planar counterpart. Furthermore, it is observed that the impedance response of the proposed device is contrary to the expected behavior due to its particular geometry. To further investigate this difference, a thorough model analysis of the measured signal and the electric field calculation is performed, revealing enhanced electron hopping/tunneling along the DNA chains due to an enriched electric field inside the tube. Likewise, conformational changes of DNA might also contribute to this effect. Accordingly, these highly integrated three-dimensional sensors provide a tool to study electrical properties of DNA under versatile experimental conditions and open a new avenue for novel biosensing applications (i.e., for protein, enzyme detection, or monitoring of cell behavior under in vivo like conditions).

Compact Nanowire Sensors Probe Microdroplets

The conjunction of miniature nanosensors and droplet-based microfluidic systems conceptually opens a new route toward sensitive, optics-less analysis of biochemical processes with high throughput, where a single device can be employed for probing of thousands of independent reactors. Here we combine droplet microfluidics with the compact silicon nanowire based field effect transistor (SiNW FET) for in-flow electrical detection of aqueous droplets one by one. We chemically probe the content of numerous (∼10(4)) droplets as independent events and resolve the pH values and ionic strengths of the encapsulated solution, resulting in a change of the source-drain current ISD through the nanowires. Further, we discuss the specificities of emulsion sensing using ion sensitive FETs and study the effect of droplet sizes with respect to the sensor area, as well as its role on the ability to sense the interior of the aqueous reservoir. Finally, we demonstrate the capability of the novel droplets based nanowire platform for bioassay applications and carry out a glucose oxidase (GOx) enzymatic test for glucose detection, providing also the reference readout with an integrated parallel optical detector.

Ultrasensitive detection of Ebola matrix protein in a memristor mode

We demonstrate the direct biosensing of the Ebola VP40 matrix protein, using a memristor mode of a liquid-integrated nanodevice, based on a large array of honeycomb-shaped silicon nanowires. To shed more light on the principle of biodetection using memristors, we engineered the opening of the current-minima voltage gap VGAP by involving the third gap-control electrode (gate voltage, VG) into the system. The primary role of VG is to mimic the presence of the charged species of the desired sign at the active area of the sensor. We further showed the advantages of biodetection with an initially opened controlled gap (VGAP ≠ 0), which allows the detection of the lowest concentrations of the biomolecules carrying arbitrary positive or negative charges; this feature was not present in previous configurations. We compared the bio-memristor performance, in terms of its detection range and sensitivity, to that of the already-known field-effect transistor (FET) mode by operating the same device. To our knowledge, this is the first demonstration of Ebola matrix protein detection using a nanoscaled electrical sensor.

Human α-thrombin detection platform using aptamers on a silicon nanowire field-effect transistor

We present a silicon nanowire-based field-effect transistor biosensor with Schottky barriers for highly specific and sensitive human α-thrombin detection. The active sensor area is decorated with thrombin-binding aptamers as receptor molecules. Each sensor chip is integrated into a microfluidic device for flow-through measurements. Instantaneous detection is provided by real-time monitoring of FET transfer curves. With this approach, thrombin concentrations between 200 pM and 200 nM are detected in a label-free, real-time manner, covering a wide dynamic range and enabling to distinguish between healthy and pathological levels. The development of simple, miniaturized devices for blood protein detection is highly interesting for medical diagnostics.

Lab-In-A-Tube: From Molecule to Cell Detection

The intriguing properties of self-assembled microtubular architectures open new possibilities to develop three-dimensional functional devices for molecule and cell analysis. [...]