Showing posts with label sensor. Show all posts
Showing posts with label sensor. Show all posts

Monday, December 17, 2018

Highly Sensitive ALD SnO2 Sensors and the Role of its Thickness in Gas Sensing Capabilities

Highly Sensitive ALD SnO2 Sensors and the Role of its Thickness in Gas Sensing Capabilities Published on Dec 4, 2018
Authors: Akhilesh Tanneeru, Zachary Taylor, Bongmook Lee, Veena Misra Abstract: 
We report superior gas sensing properties of nano-layered atomic layer deposited - tin oxide thin films with room temperature operation and discuss the role of thickness on the sensing response of the films. 25, 50, 100 cycles of tin oxide ALD films have been evaluated for response with ozone gas in the concentration range of 25ppb-100ppb. At 75ppb of ozone, relevant concentration indicated for an Asthma attack, a remarkable increase in sensitivity by 22 times is seen with the 50 cycles ALD SnO2 sensor over the 100 cycles sensor and an increase of 58 times, with the 25 cycles sensor over the 50 cycles sensor. The operating power per sensor was under 200uW including the power consumed by an UV LED (385nm wavelength) used for resetting the sensors’ baseline resistances. 

Tuesday, August 1, 2017

ALD helps searching for traces of drugs and bomb-making components

BUFFALO, N.Y. — Scientists searching for traces of drugs, bomb-making components and other chemicals often shine light on the materials they’re analyzing.

This approach is known as spectroscopy, and it involves studying how light interacts with trace amounts of matter. 

The image above depicts a new device for surface enhanced infrared absorption spectroscopy. Infrared light (the white beams) is trapped by tiny gaps in the metal surface, where it can be used to detect trace amounts of matter. Credit: University at Buffalo.
One of the more effective types of spectroscopy is infrared absorption spectroscopy, which scientists use to sleuth out performance-enhancing drugs in blood samples and tiny particles of explosives in the air.

Friday, April 24, 2015

DTU & ITMO present ultracompact all-dielectric refractive index sensors by ALD

A new type of ultracompact all-dielectric refractive index sensors with much lower losses compared to plasmonics-based sensors fabricated by ALD has been published recnetly by DTU - Technical University of Denmark and ITMO University St Petersburg. The presented results will be useful for ellipsometric characterization of multilayer stacks, as well as for a variety of sensing applications.

Nanotechweb reports: Surprising optical properties of ultra-thin dielectric multilayer films

Ultra-thin dielectric films could act as a new type of chemical sensor. This is thanks to a minute variation in layer thickness and ordering on the light reflection in a very narrow range of incident angles. Surprisingly, this new discovery reported in Nanotechnology has a high influence. The same sensitivity can be utilized for the in-situ monitoring of multilayer deposition and for the development of new high-precision models for ellipsometry.

Anomalous effective medium approximation breakdown in deeply subwavelength all-dielectric photonic multilayers FREE ARTICLE Focus on Nanophotonics

Andrei Andryieuski1, Andrei V Lavrinenko1 and Sergei V Zhukovsky1,2

1 DTU Fotonik, Technical University of Denmark, Ørsteds pl. 343, Kongens Lyngby, 2800 Denmark
2 ITMO University, Kronverkskiy pr. 49, St. Petersburg, 197101 Russia
Andrei Andryieuski et al 2015 Nanotechnology 26 184001
We present a comprehensive analysis of the applicability of the effective medium approximation to deeply subwavelength (period all-dielectric multilayer structures. We demonstrate that even though the dispersion relations for such multilayers differ from the effective medium prediction only slightly, there can be regimes when an actual multilayer stack exhibits significantly different properties compared to its homogenized model. In particular, reflection near the critical angle is shown to strongly depend on even very small period variations, as well as on the choice of the multilayer termination. We identify the geometries for which the influence of the subwavelength features is maximized and demonstrate that the difference between the reflectance from the actual multilayer and the effective medium prediction can be as great as 0.98. The results of this analysis can be useful for high-precision multilayer ellipsometry and in sensing applications.


Figure 6 from Anomalous effective medium approximation breakdown in deeply subwavelength all-dielectric photonic multilayers (Andrei Andryieuski et al 2015 Nanotechnology 26)


Wednesday, January 14, 2015

ALD ZrO2 protects Photonic crystal nanolaser biosensor for DNA detection

As reported by : A simple method to sense DNA, as well as potential biomarker proteins of cancer or other diseases such as Alzheimer's, may soon be within reach thanks to the work of a team of Yokohama National Univ. researchers in Japan.

As the team reports in Applied Physics Letters, they created a photonic crystal nanolaser biosensor capable of detecting the adsorption of biomolecules based on the laser's wavelength shift.

Equally impressive, the nanolaser biosensor enables detection of the surface charge from its laser emission intensity, which in turn can also be used to sense the adsorption of biomolecules. Using laser intensity to detect biomolecules is potentially less expensive than the fluorescent tagging or spectroscopy techniques typically used in biosensors because it is a simpler procedure.

When the team first set out to explore photonic crystal nanolaser sensors, they weren't focusing on the intensity of the laser emission because it's sensitive to the quality of the fabricated laser and, frankly, they didn't expect it to show sensing signals.

"In the beginning we focused on wavelength behavior, but quickly noticed that [the laser emission] intensity is influenced by both pH and polymers," noted Toshihiko Baba, a professor in Yokohama National Univ.'s Dept. of Electrical and Computer Engineering. "Our results were very reproducible and, interestingly, we found that the behaviors of the wavelength and intensity are independent." 
This image shows a top view of the group's nanolaser, in which the center narrow slot (horizontal line) is the main part of the sensor. The periodic holes form a photonic crystal, and although the size of the holes appears to fluctuate they've been intentionally modified so the laser's emission is effectively extracted to the top. Image: Toshihiko Baba/Yokohama National Univ.

The team was surprised by these results, which they discovered when they deposited a protective film of thin zirconium dioxide (ZrO2) over the device using atomic layer deposition, and then tried sensing in liquids of high or low pH and liquids containing charged polymers. The coating was necessary to protect the nanolaser from damage and unwanted wavelength drift.

The nanolaser device can sense surface charge because the surface charge changes the occupancy rate of electrons at the surface states in the semiconductor of the nanolaser, Baba explained. "This modifies the semiconductor's emission efficiency." 

Keisuke Watanabe, Yoji Kishi, Shoji Hachuda, Takumi Watanabe, Mai Sakemoto, Yoshiaki Nishijima and Toshihiko Baba
Appl. Phys. Lett. 106, 021106 (2015)

The emission intensity of a GaInAsP photonic crystal nanolaser is affected by the pH of the solution, in which the nanolaser is immersed. This phenomenon can be explained by the change in the redox potential, which modifies the filling of electrons at surface states of the semiconductor and hence the nonradiative surface recombination. This phenomenon allows the nanolaser to simultaneously and independently detect the refractive index and electric charges near the surface on the basis of the variation in emission wavelength and intensity, respectively. This paper demonstrates this function through alternate deposition of charged polyelectrolytes and hybridization of deoxyribonucleic acids.

Wednesday, November 12, 2014

Colnatec Unveils All-Inclusive Thin Film Controller

Colnatec is expanding its portfolio of high-precision, thin film measurement and control devices, Colnatec today announced the debut of a compact controller that unites the leading-edge technology of its Eon™ series of PC-based controllers with the modular efficiency of rackmount instrumentation.

Thin Film Controller with Integrated Display
Adaptable. Affordable. Unconventional.

With its integrated display, intuitive user interface, and durable architecture, Eon-ID™ offers a versatile design that adapts easily to a variety of settings - ranging from industrial to laboratory to clean room to research environments - matching or surpassing the capabilities of Inficon™ XTC/3™ and IC6™.

“We’ve identified a growing demand for a stand-alone thin film control solution that incorporates hardware, display, and software into a single enclosure,” said Colnatec CTO Scott Grimshaw. “In answering this demand, Eon-ID™ has exceeded our expectations. Making thin film control more accessible through affordability and efficiency of design, Eon-ID™ has the potential of not only broadening thin film science in general but driving thin film manufacturing opportunities into completely new and unexpected areas of industry.”

Among its numerous features, Eon-ID™ offers the latest Eon Software™ interface, an integrated display allowing for a greater variety of settings and applications, rackmount capability, a temperature compensation system that maintains crystal to within +/- 1°C of preset temperatures, advanced technology that increases reliability and durability in industrial environments.

"Eon-ID™ employs the same temperature-centric technology used in our Eon™ and Eon-LT™ series controllers," noted Colnatec CEO Wendy Jameson. "Eon-ID™ will specifically benefit industries using atomic layer deposition (ALD), optics, OLED, and any other process that requires precision control over very thin layers, especially at temperatures higher than 100°C. Combining precision, simplicity, and cost effectiveness, Eon-ID™ represents nothing less than the state-of-the-art in thin film science."

About Colnatec

Taking a revolutionary approach to thin film design, development, and manufacturing, Colnatec ( manufactures the only commercially available heated quartz crystal microbalances (QCM) for process control of film thickness measurement in high temperature processes such as atomic layer deposition (ALD) or chemical vapor deposition (CVD). Through the use of patented and patent-pending Colnatec technology, researchers, manufacturers, and system-builders have reduced production and run times and costs to improve overall performance - ultimately achieving higher yields and improved process control. Colnatec technology is also frequently used in, encapsulation and high flux deposition of organic light emitting diodes (OLED), optical coatings such as for anti-reflection (PVD), next generation food packaging, and medical device coating, etc. Launched in 2009, Colnatec is the recipient of Department of Energy Phase I and Phase II SBIR awards for high temperature sensors, and one of eight winners of the inaugural Arizona Commerce Authority Innovation Challenge Grant. Colnatec has built a reputation as a bold innovator and a formidable player in a tough, highly competitive marketplace.