Research

Spintronics with chiral molecules Sensors – Molecular Controlled Semi-conductor Resistor (MOCSER)  Interaction of electrons with organic and bio-molecules Nanoparticles based hybird systems Chemical Surface Patterning

Sensors – Molecular Controlled Semi-conductor Resistor (MOCSER)

We established that the organization of self-assembled monolayers on a semiconductor substrate induces charge transfer, which is not the property of the single adsorbed molecule but is a result of cooperative effect. This charge transfer process affects the electronic properties of the substrate and may induce variations in conductivity, magnetic properties, or superconductive properties.

Based on the “organization induced charge transfer” concept a device has been developed together with the group of Prof. David Cahen, the Molecular Controlled Semiconductor Resistor (MOCSER). The group investigated the principle of operation of the device and developed, based on this concept, a sensor for analyte in gases and liquid and even an infra-red light sensor.

The MOCSER is a FET- like device (field-effect transistor), only that here, the gate electrode is removed and molecules are adsorbed on top of the conducting channel (see cartoon below). Upon the molecules adsorption, the surface potential is modified and therefore a change in the device’s current is observed.

                            

• D. Cahen, R. Naaman, Z. Vager, Adv. Func. Mater. 2005, 15, 1571.
• R. Naaman, Phys. Chem. Chem. Phys. 2011, 13, 13153.

 

Gas sensing

We developed a chemical vapor sensor, based on the MOCSER device. The surface of the devices is covered with self-assembled monolayers that interact with different analytes. We further utilize these devices in an array- based structure to implement the electronic nose concept and to increase the selectivity and sensitivity of the sensor. An example of a sensor for the TATP explosive, based on this concept, is exhibited on the right.

• E. Capua, R. Cao, C. N. Sukenik, R. Naaman, Sens. Actuators B., 2009, 140, 122.
• E. Capua, A. Natan, L. Kronik, R. Naaman, ACS Appl. Mater. Interfaces, 2009, 1, 2679.

 

Bio-molecules sensing

Based on the MOCSER approach, we recently developed a bio-sensor working in aqueous conditions. We showed that such a device is stable (due to a polymerized protection layer on its surface) and very sensitive to biological processes that occur on its surface. Furthermore, the MOCSER is capable of sensing complex antigen-antibody interactions through a lipid-membrane. This work opens a new promising way for developing biosensors for in-vivo detection and studying biological processes in living cells.

• D. Bavli, M. Tkachev, H. Piwonski, E. Capua, I. de Albuquerque, D. Bensimon, G. Haran, R. Naaman, Langmuir 2012, 28, 1020.

 

Light sensing (Infra-red light sensor)

An IR sensor based on the MOCSER was developed by covering the surface of the device with a monolayer of InAs nanoparticles. Irradiation with IR leads to photo-excitation of the nanoparticles, followed by charge transfer between the nanoparticles and the substrate. This process is monitored by change in the current at the conducting channel.

 


• T. Aqua, R. Naaman, A. Aharoni, U. Banin, Y. Paltiel, Appl. Phys. Lett., 2008, 92, 223112.

 


For more details on specific projects, see the following:

  Electron spin and chiral molecules

  Sensors – Molecular Controlled Semi-conductor Resistor MOCSER
  Interaction of electrons with organic and bio-molecules
  Charge and energy transfer in hybrid organic-inorganic systems
  Chemical Surface Patterning