Ali Javey (Advisor)

Research Advised by Professor Ali Javey

Javey Group:  List of Projects | List of Researchers

BPN776: Wearable Electronic Tape

Hiroki Ota
Kevin Chen
2015

We demonstrate a high-performance wearable piezoelectric electronic-tape (E-tape) for motion sensing based on a carbon nanotube (CNT)/silver nanoparticle (AgNP) composite encased in PDMS and VHB flexible thin films. E-tape sensors directly attached to human skin exhibit fast and accurate electric response to bending and stretching movements which induce change in conductivity with high sensitivity. Furthermore, E-tape sensors for a wide range of applications can be realized by the combination of controlling the concentration of AgNPs in the CNT network and designing appropriate...

BPN746: Liquid Heterojunction Sensors

Hiroki Ota
Kevin Chen
2015

In recent years, mechanically deformable devices and sensors have been widely explored for various applications such as paper-thin displays and electronic skin for prosthetics and robotics. Liquids are extremely deformable and have shown promise for these applications, with previous works demonstrating pressure sensors with the ability to be stretched by up to 250% before failure.However, current technology is limited to a single liquid material as liquids tend to intermix when placed together, limiting the range of sensors that can be achieved. Here, in this work, we show a new...

BPN821: 3D Printed Smart Application with Embedded Electronics Sensors and Systems

Yuji Gao
2016

Our goal is the development of personalized applications using a 3D printed process which integrates liquid-state printed components and interconnects with readily available silicon IC chips layered across all three dimensions with various orientations to deliver fully integrated system-level functionalities. Our process allows for personalization of objects with electronic capabilities through the incorporation of advanced IC components and various sensing and actuation functionalities within complex 3D architectures. As an example application, our process can be used to develop...

BPN850: Wearable Sweat Rate Sensor

Li-Chia Tai
Wei Gao
2016

Wearable sensor is a growing area in which real-time monitoring of an individual’s health status can be realized. Recently, skin-worn sensors capable of screening biomarkers in human body fluids have been developed. Since human sweat contains physiologically insightful information, it is a wonderful candidate for non-invasive health monitoring. In particular, sweat rate information is highly desired as it can provide a more complete picture for sweat analysis. Hence, the objective of this work is to develop a wearable sensor capable of monitoring sweat rate.

Project end...

BPN694: Monolayer Semiconductor Devices

Matin Amani
2016

Transition metal dichalcogenides (TMDCs) have the potential to be used in the future generation of electronic and optoelectronic devices due to their superior material properties compared to the conventional semiconductors. Although many proof of concept devices have been shown using TMDCs, the presence of large contact resistances are still a fundamental challenge to be able to realize the full potential of this material family in the functional devices. In this work, we study defect engineering by using a mild H2 plasma treatment to create defects in the WSe2 lattice. Material...

BPN747: Electronic Skin: Fully Printed Electronic Sensor Networks

Kevin Chen
2016

Large area networks of sensors which are flexible and can be laminated conformally on nonplanar surfaces can enable many different applications in areas such as prosthetics, display technology, and remote stimuli monitoring. For large area applications, printed electronics are favorable over traditional photolithography and shadow mask technology from a cost and throughput point of view and we demonstrate proof-of-concept for such a printed “electronic skin” system by printing a carbon nanotube based thin film transistor (TFT) active matrix backplane using a reverse roll to plate...

BPN832: Gold-Mediated Exfoliation of Ultralarge Optoelectronically-Perfect Monolayers

Sujay B. Desai
Mark Hettick
2016

Gold-mediated exfoliation of ultralarge optoelectronically perfect monolayers with lateral dimensions up to ≈500 μm is reported. Electrical, optical, and X-ray photo­electron spectroscopy characterization show that the quality of the gold- exfoliated flakes is similar to that of tape- exfoliated flakes. Large-area flakes allow manufacturing of large-area mono­layer transition metal dichalcogenide electronics. Further work involves automating and mechanizing the transfer process for more controlled exfoliation and transfer of TMDC monolayers onto desired substrates.

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BPN777: Nonepitaxial Growth of Single Crystalline III-V Semiconductors onto Insulating Substrates

Kevin Chen
Sujay Desai
2017

III-V semiconducting materials have many characteristics such as high electron mobilities and direct band. gaps that make them desirable for many electronic applications including high performance transistors and solar cells. However, these materials generally have a high cost of production which significantly limits their use in many commercial applications. We aim to explore new growth methods which can grow high quality crystalline III-V films, using InP as an example substrate, onto non-epitaxial substrates. In addition to excellent crystal quality, critical considerations...

BPN883: Microchannel Contacting of Crystalline Silicon Solar Cells

James Bullock
Mark Hettick
2017

There is tremendous interest in reducing losses caused by the metal contacts in silicon photovoltaics, particularly the optical and resistive losses of the front metal grid. One commonly sought after goal is the creation of high aspect-ratio metal fingers which provide an optically narrow and low resistance pathway to the external circuit. Currently, the most widely used metal contact deposition techniques are limited to widths and aspect-ratios of ~40 μm and ~0.5, respectively. In this study, we introduce the use of a micropatterned polydimethylsiloxane encapsulation layer to form...

BPN818: Fully-Integrated Wearable Sensor Arrays for Multiplexed In Situ Perspiration Analysis

Hnin Y.Y. Nyein
Wei Gao
Mallika Bariya
2017

A flexible and wearable microsensor array is described for simultaneous multiplexed monitoring of heavy metals in human body fluids. Zn, Cd, Pb, Cu, and Hg ions are chosen as target analytes for detection via electrochemical square wave anodic stripping voltammetry (SWASV) on Au and Bi microelectrodes. The oxidation peaks of these metals are calibrated and compensated by incorporating a skin temperature sensor. High selectivity, repeatability, and flexibility of the sensor arrays are presented. Human sweat and urine samples are collected for heavy metal analysis, and measured results...