Tag Archives: temperature

A Robust High-Temperature Semiconducting Carbon Monoxide (CO) Sensor

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Summary:

In many combustion-related industries, monitoring CO levels is critical for estimating the efficiency of the combustion process. With the ideal balance of oxygen to fuel, pollution is also minimized. Existing gas sensors based on metal oxide materials typically operate at 200-300 degrees C. Researchers at The Ohio State University have developed a CO sensor for hostile industrial environments (450-800 degrees C) that responds to CO at concentrations approaching one part per million. These sensors can be miniaturized with minimal electrical power requirements, and exhibit stable baseline resistance and good response and recovery times. To the best of our knowledge, we know of no existing solid state sensors that equal the performance of these sensors.

Potential Applications:

  • Combustion control
  • Heat treating
  • Metal processing and casting
  • Glass and ceramics manufacturing
  • Food processing
  • Power plant operations
  • Automotive applications

Advantages:

  • Responds to CO at ppm levels
  • Can be used in high-temperature, hostile environments (450-800 degrees C)
  • Minimal drift
  • Quick recovery times
  • More economical than existing high-temperature sensor technologies

Room-Temperature NDR Polymer Diodes for Flexible, Low-Power Electronics

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Summary:

Devices that exhibit a phenomenon known as negative differential resistance (NDR) have tremendous potential to deliver the kind of low-power circuitry needed in a variety of electronics applications. To understand NDR, it is instructive to recall Ohm’s Law, V=IR. For a fixed resistance (R), as voltage (V) increases, current (I) increases in a linear fashion. In NDR, there is a voltage range where increasing voltage actually results in a decreasing current. This behavior has many beneficial design properties, one of which is the design of low power memory and logic or even energy scavenging from the environment, eliminating the need for a self-contained battery.

Until now, successful demonstrations of NDR have been limited to rigid, inflexible semiconductor-based devices that are unsuitable for certain applications. Researchers at The Ohio State University have developed a polymer-based device that exhibits NDR and has the flexibility needed for advanced applications such as smartcards and wearable electronics. These devices enjoy very fast operation, which leads to high performance while consuming very little power. Furthermore, these devices can be manufactured in a very cost-effective manner using simple printing techniques.

Potential Applications:

  • Smartcards
  • Energy Scavenging
  • Development of advanced logic and memory circuits on flexible substrates

Advantages:

  • Large and reproducible NDR, at room temperature, in a flexible polymer device!
  • Low cost and simple solution processing
  • Fast operation at low power

Humidity-Interference Free, High-Temperature CO2 Sensor

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Summary:

Carbon dioxide sensors are becoming increasingly important in many applications including monitoring air quality, CO2 sequestration, measuring metabolic activity in animals, and controlling combustion. While commercial sensors for such applications exist, there is nothing currently on the market designed for reliability and effectiveness in high temperature and high humidity environments. Researchers at The Ohio State University have developed a reliable, high-performance carbon dioxide electrochemical sensor that works across a wide range of temperatures, is insensitive to humidity, and detects CO2 across a wide range of concentrations. These sensors can be manufactured by thin and thick film processing techniques, and can therefore be miniaturized resulting in a sensor with milliwatt power requirements for operation.

Potential Applications:

  • Combustion control
  • Monitoring of metabolic activity
  • CO2 monitoring in harsh environments
  • Power plant and industrial emissions monitoring
  • Automotive and aerospace emissions monitoring
  • CO2 sequestration applications

Advantages:

  • Humidity-interference free
  • Fast response and recovery
  • Long-term sensor stability in humid conditions over a wide range of temperature
  • Solid-state device

Low Temperature Working Carbon Monoxide (CO) Sensor Based on Au/SnO2 Core-Shell Nanoparticles

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Summary:

SnO2-based CO sensors are widely used in domestic and industrial applications and belong to the class of metal-oxide semiconductor (MOS) sensors. This class of sensor is easy to manufacture and miniaturize, and sensitivity and selectivity are both tunable. Also, electrochemical measurements are easily realized, require simple electronics, and integration into electronic devices is straightforward. However, since sufficient oxygen vacancies are needed for conduction, MOS sensors typically operate at elevated temperatures, which requires energy consumption and reduces sensor lifetimes. Researchers at The Ohio State University have developed a MOS CO sensor based on Au/SnO2 core-shell nanoparticles that is operable in the 25 to 150 deg. C range. Sensor response is highly reproducible and recovery is fast in this temperature range, and high sensitivity was exhibited.

Potential Applications:

  • Home, office, and industrial CO monitoring for occupant and fire safety
  • Low temperature and low power requirement makes it compatible with mobile devices

Advantages:

  • A MOS electrochemical CO sensor that operates in the 25 to 150 deg. C range!
  • Increased safety and sensor longevity as no heating device is needed
  • Greatly reduced energy consumption
  • Extremely low cost and easy manufacturing
  • Simple electronics for easy device integration