Josephine B. Chang

Printable polythiophene gas sensor array for low-cost electronic noses

A route for generating arrays of printable polythiophene-based gas sensor materials suitable for low-cost manufacturing is demonstrated. Materials with complementary sensor responses are synthesized by incorporating functional groups into the molecule, either along the polymer backbone or as end-capping groups. Using these materials as printable sensor inks, a functional, integrated gas sensor array chip is fabricated using additive deposition techniques. The sensor array shows sensitivity to a range of volatile organic compounds down to concentrations of 10ppm. A three-terminal thin film transistor structure is used, allowing the extraction of multiple parameters that help to elucidate the mechanisms responsible for sensor response and the role of the functional groups in this response.

Improved superconducting qubit coherence using titanium nitride

We demonstrate enhanced relaxation and dephasing times of transmon qubits, up to ∼60u2009μs, by fabricating the interdigitated shunting capacitors using titanium nitride (TiN). Compared to qubits made with lift-off aluminum deposited simultaneously with the Josephson junction, this represents as much as a six-fold improvement and provides evidence that surface losses from two-level system (TLS) defects residing at or near interfaces contribute to decoherence. Concurrently, we observe an anomalous temperature dependent frequency shift of TiN resonators, which is inconsistent with the predicted TLS model.

Effect of active layer thickness on bias stress effect in pentacene thin-film transistors

The bias stress effect in pentacene thin-film transistors is characterized for different active layer thicknesses. We show that the shift in threshold voltage under applied bias is accelerated as the pentacene semiconductor layer thickness is increased from 10to80nm, and that this trend is not correlated with current, initial threshold voltage, or turn-on voltage. This study sheds light on the role of active material above the conductive channel in thin-film devices and describes effects that are important to consider when optimizing the structure of organic thin-film transistors.

Printed electronics for low-cost electronic systems: Technology status and application development

In recent years, printing has received substantial interest as a technique for realizing low cost, large area electronic systems. Printing allows the use of purely additive processing, thus lowering process complexity and material usage. Coupled with the use of low-cost substrates such as plastic, metal foils, etc., it is expected that printed electronics will enable the realization of a wide range of easily deployable electronic systems, including displays, sensors, and RFID tags. We review our work on the development of technologies and applications for printed electronics. By combining synthetically derived inorganic nanoparticles and organic materials, we have realized a range of printable electronic ldquoinksrdquo, and used these to demonstrate printed passive components, multilayer interconnection, diodes, transistors, memories, batteries, and various types of gas and biosensors. By exploiting the ability of printing to cheaply allow for the integration of diverse functionalities and materials onto the same substrate, therefore, it is possible to realize printed systems that exploit the advantages of printing while working around the disadvantages of the same.

Electronic Noses Sniff Success

E-nose technology has quietly advanced during the past two decades. Commercial models equipped with sensor arrays came to market in the mid-1990s, and today theyre used to distinguish wines, analyze food flavors, and sort lumber. Benchtop systems are also used in the pharmaceutical, food, cosmetics, and packaging industries, while smaller, portable units are used to monitor air quality. But these noses cost in the range of US

Initial evaluation and comparison of plasma damage to atomic layer carbon materials using conventional and low Te plasma sources

5000 to

First realization of the piezoelectronic stress-based transduction device.

100 000. A coming convergence between e-nose technology and advances in printed electronics will finally bring the price down; way down. Within a decade well see e-noses that cost tens of dollars and appear in smart packaging for high-end items like pharmaceuticals or as part of intelligent or interactive appliances- picture a refrigerator that knows when milk has gone bad. Prices could easily drop to under a dollar by 2020. The secret? Conducting polymers. Developers of both electronic noses and printed electronics are exploiting these materials, which can be sensitive to the chemicals that make up odors and are also capable of producing electrical signals. E-nose developers are concentrating on honing the sensing properties of conducting polymers, while the printed-electronics people are investigating ways of using these materials to fabricate ultralow-cost electronics. Combining the fruits of these two separate efforts will finally bring e-noses into our supermarkets, homes, and daily life.

Printed organic transistors for low-cost tagging and sensing applications

The ability to achieve atomic layer precision is the utmost goal in the implementation of atomic layer etch technology. Carbon-based materials such as carbon nanotubes (CNTs) and graphene are single atomic layers of carbon with unique properties and, as such, represent the ultimate candidates to study the ability to process with atomic layer precision and assess impact of plasma damage to atomic layer materials. In this work, the authors use these materials to evaluate the atomic layer processing capabilities of electron beam generated plasmas. First, the authors evaluate damage to semiconducting CNTs when exposed to beam-generated plasmas and compare these results against the results using typical plasma used in semiconductor processing. The authors find that the beam generated plasma resulted in significantly lower current degradation in comparison to typical plasmas. Next, the authors evaluated the use of electron beam generated plasmas to process graphene-based devices by functionalizing graphene with...

Off-state modulation of SOI floating-body

We present the first realization of a monolithically integrated piezoelectronic transistor (PET), a new transduction-based computer switch which could potentially operate conventional computer logic at 1/50 the power requirements of current Si-based transistors (Chen 2014 Proc. IEEE ICICDT pp 1-4; Mamaluy et al 2014 Proc. IWCE pp 1-2). In PET operation, an input gate voltage expands a piezoelectric element (PE), transducing the input into a pressure pulse which compresses a piezoresistive element (PR). The PR resistance goes down, transducing the signal back to voltage and turning the switch on. This transduction physics, in principle, allows fast, low-voltage operation. In this work, we address the processing challenges of integrating chemically incompatible PR and PE materials together within a surrounding cage against which the PR can be compressed. This proof-of-concept demonstration of a fully integrated, stand-alone PET device is a key step in the development path toward a fast, low-power very large scale integration technology.

Printed transistors and passive components for low-cost electronics applications

Printing is considered an attractive technology for realizing electronic functionality at low cost. Inkjet printing, in particular is very attractive for applications requiring low material consumption and spatially-specific material deposition. We report on inkjet-printed transistors offering performance approaching that of amorphous silicon, fabricated using nanoparticle-based metallization and organic-based semiconductors and dielectrics. The performance of these devices is among the highest reported for fully-printed transistors. We explore the optimization of the various printing parameters to maximize device performance and film properties. We also demonstrate the use of organic devices in arrayed electronic nose gas sensors and biosensors, exploiting the unique spatially-specific material deposition capabilities offered by inkjet printing.