Centre for Sensors, Instruments and Systems Development

Universitat Politècnica de Catalunya

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A photonics based biosensor with plasmon...

Image of cantilever during measurement
Experimental setup
Displacement of the cantilever, reference
Displacement of the cantilever, sample


A photonics based biosensor with plasmonic accuracy and low cost.

Principal investigator

Santiago Royo Royo [+info]


The project aims to develop a proof of concept pre-prototype capable of delivering results with comparable or superior accuracy to those obtained by plasmonic techniques using differential self-mixing interferometry techniques (DSMI) as the basis technology, and to explore options for its exploitation using the preprototype as demonstrator. 

DSMI is a method developed and patented at CD6 from UPC, which can measure changes in the optical path with a resolution of just a few nanometers. Potentially, therefore, overcomes the resolution and cost of plasmonic sensors while it measures the same parameter. The technique is based on classical self-mixing interferometry (SMI), where the effect of interference occurs inside the cavity of a laser diode as a result of the backscatter of the beam of a partially reflective target. This interference modulates the power emitted by the laser. It is possible to process this power modulation ot extract data on the changes in the optical path covered. This is an extremely economical method, self-aligned, compact and robust, which works just pointing the laser diode to the region to be measured. The method has been already used to measure various biological and physical constants.

External links

LLAVOR Program


Comunicació a congrés internacional (en anglès): "Azcona, F.; Atashkhooei, R.; Royo, S.; Mendez Astudillo, J.; Jha, A. (2013): "A method to measure sub nanometric amplitude displacements based on optical feedback interferometry." Modeling Aspects in Optical Metrology IV, 13-14 Maig 2013. Munich, Germany. Proc. of SPIE Vol. 8789, 878908" (2013)

Comunicació a congrés internacional (en anglès): "R.Atashkhooei, S.Royo, F.Azcona, U.Zabit “Analysis and control of speckle effects in self-mixing interferometry” IEEE Sensors Conference, Limerick, 28-31 October 2011, Oral " (2011)

Paper: "Atashkhooei, R., Royo, S., Azcona, F.J. (2014): "Adaptative autofocus technique for speckle control in optical feedback interferometry". Sensors and Actuators A 216. P. 243-248"

Patent: "A method of measuring a displacement-related parameter using a laser self-mixing measuring system, and a laser self-mixing measuring system"

CD6 Centre for Sensors, Instruments and Systems Development
Rambla de Sant Nebridi, 10  ·  08222  ·  Terrassa (Barcelona)