Nanomechanical Sensors” – What Is a Nanosensor and How Is It Different from a Conventional Sensor

Department of Micro and Nanotechnology

”Nanomechanical sensors” – What is a nanosensor and how is it different from a conventional sensor

Zachary J. Davis Associate Professor MIC-DTU Where is the nano world? Department of Micro and Nanotechnology What is a nanosensor? Department of Micro and Nanotechnology

• a sensor that has some physical aspect in the nano-scale regime • a sensor that utilizes/detects phenomena exhibited in the nano-scale regime

AFM – atomic force microscope

• AFM cantilevers with tip on the nano-scale (d~10nm) • Utilizes atomic forces that dominate in the nano-scale • Van der Waals • Interatomic repulsion What nanosensors can give us Department of Micro and Nanotechnology

Invaluable tools to understand and to experiment on the nano-scale → New highly improved sensor systems with unique functionalities Cantilever based sensors Department of Micro and Nanotechnology

Change of surface Change of temperature Change of mass stress

Gene/Protein Explosives Gas/particle detection detection detection Static mode sensing Department of Micro and Nanotechnology

• Integrated piezoresistive read-out • resistors are encapsulated which allows operation in liquids • large arrays → multiple recognition, redundancy Silicon devices Department of Micro and Nanotechnology

200 ImmobilisationMogens Havsteen Jakobsen 180 DNA hybridization Hybridisation 160

140

120

100 V µ 80

60 Silicon piezoresistive readout 40 20

0 100 200 300 400 500 600 700 Time (s)

• Gene detection possible •proteomics • antibody/antigen recognition Polymer Devices - immobilisation Department of Micro and Nanotechnology

Vin Vout

☺ Lower Young’s modulus Low strain gauge ☺ Low electrical noise Alicia Johansson Explosive vapour detection Department of Micro and Nanotechnology

Heated to 860 Co in It is possible to detect a few less than 0.5ms picograms of DNT

• reusable device • no functional layer needed

Anders Nanoparticle detection – dynamic mode Department of Micro and Nanotechnology

FP7 EU project: Søren ’Nanodevice’ Quantative particle detection Department of Micro and Nanotechnology

R~0.9 µm, m~60pg

S. Dohn, APL 86(26) (2005) Conclusions Department of Micro and Nanotechnology

• Nanosensors are not just small sensors, but rather sensors that utilize/detect nanoscale phenomena

• Nano-mechanical sensors have a huge potential for a range of different applications – High sensitivity – Arrays -> multiple detection/redundancy – Low power -> autonomous systems – Batch processing -> low cost