Anatase TiO 2 nanoparticles were produced by flame spray pyrolysis (FSP) and characterized by transmission/scanning electron microscopy, X-ray diffraction and nitrogen adsorption. Thick films (30-50 µm) of these powders were prepared by drop-coating technique and tested for sensing of acetone, isoprene and ethanol at 500 °C in dry N 2 /O 2. A high n-type sensor signal was recorded at ppm levels of these organic vapors with fast response and recovery times. Heat-treatment at 900 °C caused a nearly complete anatase to rutile transformation and a transition to p-type sensing behavior. The rutile sensor had a poor signal to all hydrocarbons tested and considerably longer recovery times.

This paper describes a sensor nanotechnology suitable for non-invasive monitoring of a signaling gas, such as acetone, in exhaled breath. This is a nanomedicine tool comprised of a selective acetone nanoprobe working on the principle of ferroelectric poling sensing, and a microelectronics circuit for comparing the actual sensor signal to a predetermined threshold value, displaying the result using LED signals. This on/off type non-invasive diagnostics platform technology is based on nanotechnology, gives a fast response, it is simple to operate and inexpensive to manufacture, and may truly revolutionize personalized medicine.

The detection and monitoring of gases in exhaled human breath up to date has been limited by the lack of appropriate materials and technologies which could rapidly and selectively identify the presence and monitor the concentration of trace levels of specific analytes-biomarkers. We present a metal oxide-based nanosensor that is highly specific to ammonia gas in breath-simulating environments at low part-per-billion concentrations. The design of a handheld breath analyzer for gas detection in exhaled human breath is described. Semiconducting ceramics are presented as suitable sensor materials for easy and affordable non-invasive diagnostics.

Measurement of NO gas in exhaled human breath may be used to monitor oxidative stress and pulmonary diseases. Until now, only bulk, expensive, chemiluminescence-based NO monitors have been available to medicine. A nanosensing probe based on WO3 selectively detecting minute nitric oxide gas concentrations in the presence of interfering volatile compounds is presented. This is possible due to the chemical affinity of rhenium trioxide based phases to oxidizing gases. The NO nanoprobe is expected to lead to portable and affordable, noninvasive, single breath sampling, NO diagnostics.