The sensing capabilities of Carbon nanotubes [CNTs] are often reported in the literature [1,2] but we describe here a commercial sensor based on an amperometric detection method using CNT electrodes. The commercial availability means that it has been thoroughly vetted not only for sensitivity, but also for practical response time, selectivity, and stability in T, P, RH and time dimensions. The CNT-composite electrodes are robust, and while not as inert as the sp4 diamond, they exhibit chemical stability >sp3 carbons. The significant advantage is the extremely high surface area with virtually every atom a surface atom and therefore high catalytic activity at low loadings. These characteristics are important in high volume sensors so that small size and low cost are enabled along with the inherent low power of electrochemical sensors. This combination of characteristics along with the practical manufacturing by using printed electronics approaches is our key to bridge the cost-performance gap and penetrate into high volume consumer and environmental markets with these sensors. The first two environmental gases that use the nano-catalyst electrodes are NO₂ and O₃ in air at ppb levels.  

In order to address global problems with sensors, we know that we will need millions to billions of sensors. This implies a low cost and a sensor design amenable to high volume production. The solution to the World Health Organization’s recognized air quality crisis is accelerated by a global air quality network and this network will need Ozone and nitrogen dioxide sensors as these are lung irritants produced by anthropogenic activity. Business models for the practicality of trillions of connected devices and sensors are emerging in the IoT. Our manufacturing process for the nano-catalyst electrodes involves screen printing for low cost and high volume and it combines the best practices of the semiconductor microfabrication industry with the speed and low cost of the Printed Electronics revolution. This approach can meet the needs for new high volume low cost sensors and accelerate our fight against climate change. Many more sensor products and applications are expected as crowd-sourced pollution measurements are enabled and IoT connected devices allow instant communication of vital information.

 

1] J. R. Stetter and G. J, Maclay, “Carbon Nanotubes and Sensors: A Review,” in Advanced Micro and Nano Systems, Volume I, Chapter 10, Baltes et al., eds. Wiley-VCH Verlag-GmbH and Co., Weinheim, Germany, pp357-382, 2004 ISBN 3-527 30746-X, [Invited].

2] A. Star, T-R.Han, V. Joshi, and J.R. Stetter, “Sensing with Coated Carbon Nanotube Field Effect Transistors,” Electroanalysis 2004, 16 (1-2), 108-112.