Hybrid Devices for Molecular Systems and Factories Monitoring

  • Schematics representing a vision for a future integrated silicon nanowire ion sensor. Arrays of nanowires with different functionalization schemes allow for the specific and spatially-resolved detection of different ions as well as pH.
    Schematics representing a vision for a future integrated silicon nanowire ion sensor. Arrays of nanowires with different functionalization schemes allow for the specific and spatially-resolved detection of different ions as well as pH.

When it comes to designing, interconnecting and testing functionality in molecular systems built from different molecular modules, interfaces between the different system elements play a critical role. Using arrays of charge-sensitive Si nanoribbon transistors, we aim at characterizing ionic and molecular transport processes through membranes to monitor the behaviour of molecular systems and factories.  On the long term, we will monitor cross-communication between molecular factories to provide feedback mechanisms able to regulate biochemical processes.

An important aspect in studying molecular systems is the monitoring of the activity of biochemical systems functioning thanks to ion exchange processes. The exchange of ionic species e.g. via cellular transmembrane channels, and the associated arising electrochemical gradients play a crucial role in biochemical processes. Using arrays of silicon nanowire-based ISFETs, time and spatially correlated measurements of the ionic concentrations are possible at the microscale.

We have successfully demonstrated pH sensing using arrays of silicon nanowires with Al2O3 or HfO2 as proton-sensitive layers. A first step towards a multifunctional sensing platform has been achieved by modifying the surface of the nanowires with self-assembled monolayers of ion-specific receptors. Using this hybrid system, the selective detection of Na+, K+, Ca2+ and F- has been demonstrated. By independently functionalizing nanowires arrays in a single device, simultaneous sensing of multiple analytes was achieved. 

We are expanding the application of ISFETs towards the monitoring of transport mechanisms involved in molecular systems. In collaboration with different NCCR partners, we are investigating novel methods for the deposition of membranes on the surface of silicon nanowires. Using our ISFET platform, we aim at measuring and characterizing ionic transport through membranes engineered with molecular channels. On the long term, our SiNWs platform will serve as an analytical tool to monitor and regulate the activity of on-chip molecular compartments. By interconnecting these compartments or factories via direct fluidic channels or via membrane flows, we foresee the integration of exchange and feedback mechanisms between the factories.

Articles

R. L. Stoop, K. Thodkar, M. Sessolo, H. J. Bolink, C. Schönenberger, M. CalameCharge Noise in Organic Electrochemical Transistors“ Phys. Rev. Appl. 7, 014009 (2017). [Link]
C. E. HousecroftC. G. PalivanK. GademannW. MeierM. CalameV. Mikhalevich, X. Zhang, E. PielM. SzponarskiA. WieslerA. Lanzilotto, E. C. Constable, A. Fanget, R. Stoop “‘Active surfaces’ as Possible Functional Systems in Detection and Chemical (Bio) Reactivity“ Chimia 6, 402 (2016). [Link]
M. Wipf, R. L. Stoop, G. Navarra, S. Rabbani, B. Ernst, K. Bedner, C. Schönenberger, M. CalameLabel-Free FimH Protein Interaction Analysis Using Silicon Nanoribbon BioFETs“ ACS Sens., DOI: 10.1021/acssensors.6b00089 (2016). [Link]
R. L. Stoop, M. Wipf, S. Müller, K. Bedner, I. A. Wright, C. J. Martin, E. C. Constable, A. Fanget, C. Schönenberger, M. CalameImplementing Silicon Nanoribbon Field-Effect Transistors as Arrays for Multiple Ion Detection“ Biosensors 6, 21 (2016). [Link]
R. L. Stoop, M. Wipf, S. Mueller, K. Bedner, I. A. Wright, C. J. Martin, E. C. Constable, W. Fu, A. Tarasov, M. Calame, C. Schönenberger “Competing surface reactions limiting the performance of ion-sensitivefield-effect transistors“ Sens. Actuators, B 220, 500 (2015). [Link]

Who works with whom?

Dr. habil. Michel Calame from EMPA (Transport at Nanoscale Interfaces Laboratory) leads this project and works with PhD-students Yves Mermoud, and with postdoc Masoud Baghernejad.

Group

Read more about the Calame-Group here.

Collaborations

We collaborate with Dimitrios Fotiadis (light-triggered ion pumps in artificial and biomembranes), Catherine Housecroft (surface functionalization and ion receptors), Wolfgang Meier and Cornelia Palivan (ion channels in artificial membranes), Francesco Stellacci (surface functionalization and ion receptors), and with Oliver Wenger (charge transfer in molecular systems).