Chemical Sensor Platform Research Articles

Design and fabrication of enhanced polymer waveguide platforms for absorption-based optical chemical sensors

The development of mass-producible polymer waveguide chips as enhanced platforms for absorption-based optical chemical sensors employing thin colorimetric films is reported here. The chip design is based on a previously reported theoretical study relating to the optimization of the sensitivity of optical absorption-based sensors employing a single reflection configuration. Here, the theoretical analysis is extended to a multiple reflection configuration in order to determine the dependence of sensitivity on interaction length, and the findings are investigated experimentally. The existence of the optimum sensing conditions predicted by theory is demonstrated empirically by examining the pH response of polymer waveguide platforms coated with a sol–gel derived sensing layer doped with a colorimetric pH indicator. This work has major implications for the fabrication of miniaturized, disposable sensor platforms that demonstrate enhanced sensitivity when compared with those utilizing more commonly employed optical configurations.

SENSORIX AG: Development, Optimization, and Control of Biotechnological Processes Through Continuous Online Analytics with Chemical Sensors and Biosensors

The four-year-old ETH Zürich spinoff company SENSORIX develops, produces and sells analytical instrumentation for process development, optimization and control in biotechnology. SENSORIX successfully launched its first products for fermentation and cell culture applications last year. Based on a flexible and modular platform for biosensors and chemical sensors they can be tailored to match the changing needs of the customer quickly and easily. All the instruments are connected online to the bioprocess and deliver a continuous measurement signal.

Large Scale Production of Carbon Nanotube Transistors: A Generic Platform for Chemical Sensors

AbstractWe report our work on the fabrication of nanotube-based field effect transistors (NTFET). Nanotubes were grown by chemical vapor deposition using various approaches, including a new formulation of nanotube growth catalysts that were directly patterned using UV lithography. We also report NTFETs based on randomly oriented nanotube networks that have a modulation of one. Finally, we report that a systematical and statistical characterization of millions of devices has led to the development of a robust process that may be useful in large scale production of reproducible, nanotube-based FETs, which, in turn, can be used as a generic platform for chemical sensors.

Integrated organic light-emitting device/fluorescence-based chemical sensors

A fluorescent chemical sensor platform, integrating an organic light-emitting device (OLED) light-source with a fluorescent probe, is demonstrated for a subsecond-fast oxygen sensor. The integration results in strong light coupling and negligible heating of the sensor film or analyte. The potential in vivo operation of compact, stand-alone, battery-powered, OLED-based miniaturized sensor arrays for chemical and biological applications is discussed.

Multi-analyte optical chemical sensor employing a plasticsubstrate

A dual-analyte optical chemical sensor platform based on thesurface patterning of fluorescent dyes immobilized in sol-gel thin filmsis demonstrated as a proof of principle for a potential multi-analytedetection system with implications for lab-on-a-chip technology. Acombination of hot embossing and an eccentric spin-coating technique wasused to achieve discrete deposition of oxygen and carbon dioxide sensitivezones on a single waveguiding platform. Imaging of fluorescence from theoxygen and carbon dioxide sensing areas was performed using a low-cost CCDcamera and fluorescence quenching on analyte exposure was characterized.

Advanced Sensor Technology Based on Oxide Thin Film—MEMS Integration

Many of the most significant advances in achieving improved sensor performance have been tied to the integration of thin film oxides with micromachined and microelectronic technologies (MEMS). Arrays of microcantilever beams or microhotplates show great promise as chemical sensor platforms exhibiting enhanced selectivity and markedly reduced power dissipation. Microcantilever beams demonstrate exceptional sensitivity to chemical, thermal and other physical stimuli. Microhotplates, provide the opportunity to discriminate between chemical species by control of reaction rates. We review recent key developments in the micromachining of suitable structures, the means for incorporating active oxide films and the performance of individual and arrays of sensor devices.

Technical Aspects of Microscale Flight Systems

Micro Air Vehicles (MAVs) have excellent potential utility as flight platforms for optical, acoustic, electronic and chemical sensors for operation in hazardous sites with aerial access. The dimensions and performance specifications call for a 100 g take-off mass with 100-200 mm wingspan that must fly at 5-20 m/s for approximately 30 minutes. Owing to the low operating Reynolds number (Re), the aerodynamic performance of all lifting surfaces is degraded. The small scales and speeds also mean that atmospheric turbulence has a severe effect, and small thermal cycle engines that could profit from the high energy densities of fossil fuels are unavailable. It is thus difficult to obtain good performance. Studies have been made of wing plus propeller systems, rotor systems and flapping wing systems. In all cases, LID is in the range of 5-10. Flapping is about as efficient as propeller motion at this Re, but more complicated mechanically. The ThrustWing is a configuration derivative of the dragonfly, with characteristics lying between a helicopter and an ornithopter. It has both zero and forward flight capabilities, and appears to have good potential as a MAV configuration. Finally, the effects of atmospheric turbulence are described and shown to fall into four qualitatively different categories as turbulence intensity increases. Due to favourable scaling, the stresses in MAVs will be very low, and although turbulence will cause large G loads on the MAV, no structural damage will result.

Inorganic sensors utilizing MEMS and microelectronic technologies

The most significant recent advances in achieving sensor sensitivity and selectivity has been tied to the integration of thin film sensors with micromachined and/or microelectronic technologies. Arrays of micro-hotplates, microcantilever beams and metal oxide semiconductor devices show great promise as chemical sensor platforms exhibiting enhanced selectivity and markedly reduced power dissipation. Microcantilever beams, presently under development, demonstrate exceptional sensitivity for thermal, optical and magnetic stimuli.

Glucose Biosensor Based on a Sol-Gel-Derived Platform

Sol-gel-derived glasses have emerged as a new class of materials wells suited for the immobilization of biomolecules. As a consequence, they are also finding new applications as platforms for chemical sensors. Room temperature (or lower) processing conditions, chemical inertness, negligible swelling effects, tunable porosiy, and the high purity of sol-gel-derived glasses make them ideal for many types of sensor applications. We report here on the characterization of tetraethyl orthosilicate-(TEOS-) derived thin sol-gel films, doped with glucose oxidase (GOx), as a sensing platform for a prototypical biosensor