Low-Cost Sensors for Detection of Volatile Compounds for Breath Analysis

Yerushalmi Roie, HUJI, Faculty of Science, The Institute of Chemistry
Paltiel Yossef, HUJI, School of Computer Science and Engineering, Applied Physics


Highly sensitive, self formed and simple to fabricate nano junction devices changing resistance in the presence of minute concentration of volatile gases:



  • Detectors of volatile gas, including combustible gases, are essential safety tools in the industry as well as in environmental, homeland security and military applications.
  • Common catalytic sensors, based on heated catalysts which react with hydrocarbon gases,  require routine calibration because the catalysts material may become poisoned or inactive due to contamination. Also, extended exposure to high concentrations of many volatile gases, including combustible gases, may degrade the sensor performance.
  • Other common gas sensors are based on detecting absorption variations of IR radiation in the presence of volatile and combustible gases. Here, the initial cost of the optical system is high, and the need to tailor optical properties of the light source and detector setup to the specific monitored gas are significant drawbacks of this method.
  • Our detectors are highly sensitive to variety of volatile gases and can be produced using low cost, large scale nano-technology production techniques.


Nano-particle Electronic Junction Sensors

Optical image of nanoswitch junctions array grown selectively in lithographically defined switch shapes. Scanning Electron Microscope image of the junction:Conductive nano-wires are bridging the gap between the two metal electrodes. (b) Schemaic diagram of the nano-switch.


Our Innovation

  • Our solution is targeting to produce large scale, cheap yet  flexible, indicators based on a simple nano-switch electrical device.  We developed a simple self-organized, highly sensitive detectors of volatile molecules based on molecular nano-crystal electronics.
  • The nanoswitches are made of hybrid gold-tipped semiconducting nanowires connected to macroscopic electrodes. A molecular scale gap is formed and is used for adsorbing the analyte molecules, thereby causing a prominent change in the (normally closed) nano-junction conductance.
  • Our bottom-up approach is fast and scalable enabling simple fabrication of multitude electronic nanojunctions, confined in devices shaped using classical robust lithographic-chemical methods.
  • This method is the basis of a platform for molecular detectors as well as for fundamental research in molecular electronics.



Our devices are designed to detect minute traces of potentially dangerous compounds of volatile /combustible and organic compounds through simple, low cost technology.

Widely spread industrial applications, growing military and home-security threats, including variety of toxic chemical agents proliferation, all require sensitive affordable volatile gas detectors.

Ever-growing environmental awareness and uses require sensitive yet simple, low cost detectors.


The Opportunity

  • Nano-structures are becoming primary components of future electronic devices. The use of mass fabrication techniques in nano technology enables mass production of our new volatile molecular detectors at low cost.
  • The nano devices proposed here can be sensitive enough to detect small changes in the surface properties of the device components. Our method of preparing the nanoswitches can also serve as a platform for fundamental research in molecular electronics.
  • The unique hybrid nanostructure method shows a potential for realizing a wide range of molecular detectors by altering the conductance of each part of the hybrid structure.
  • Last but not least, the new nanostructure based detectors may become a solution of choice for mass producing of sensitive, low cost sensors of volatile gas detectors for the consumers market.


Researcher Information:

Patent Status

Granted US 11/078,073