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Ultra-High-Frequency Surface-Acoustic-Wave microfluidics and biosensors

Venerdì 7 dicembre 2018, ore 11.00, aula Seminari, terzo piano, edificio Fisica, Dipartimento FIM, Modena

Relatore: Marco Cecchini (NEST - Istituto Nanoscienze CNR and Scuola Normale Superiore di Pisa)

Abstract: Rayleigh Surface acoustic waves (SAWs) are an effective means to interact with fluids and activate a number of microfluidic phenomena, such us mixing, droplet actuation, microparticle manipulation, nebulization and micropumping, to name but a few. Moreover, in a different configuration, SAWs can also be exploited for sensing applications. The SAW operation frequency is a fundamental parameter that sets the relevant length-scales of the device, and that can importantly limit the miniaturization and portability of the devices, as well as multiplexing operation and the integration of many operational blocks on the same chip. Here, I discuss the relevant length scales in sub-nanometer amplitude SAW-driven acoustic streaming and illustrate the absence of any physical limitations beyond fabrication capabilities preventing the downscaling of SAW-driven internal streaming to nanoliter microreactors and beyond[1]. GHz-SAWs are experimentally shown to importantly allow the reduction of droplet volume in digital microfluidics, and of the microchannel size in case of acoustic counterflow[2]. Finally, GHz-SAW acoustic resonators are fabricated and proposed for biosensing applications (Fig. 1), demonstrating biomolecular detection in liquid after drying with a limit of detection far better than that of standard commercial gravimetric sensors (i.e., quartz-crystal-microbalances)[3].


Figure 1. Biosensor Chip design and biosensing performance. a) Exploded scheme of the biosensor chip. b) Photo of the mounted biosensor chip with external connections for electrical measurements. c1) and c2) Representative optical microscope images of a resonator. Scale bars are 200 um (c1) and 40 um (c2). c3) Representative scanning electron microscopy detail of a Positive Negative Reflector (scale bar is 2 um).
Figure 2. (d) Biosensor performance characterization: resonance shifts for different streptavidin concentrations. The sensor was functionalized with biotin-PEG-SH.

[1] RJ. Shilton, V. Mattoli, M. Travagliati, M. Agostini, A. Desii, F. Beltram, M. Cecchini, Advanced Functional Materials 25 (37), 5895-5901 (2015)
[2] RJ. Shilton, M. Travagliati, F. Beltram, M. Cecchini. Advanced Materials 26 (29), 4941-4946 (2014)
[3] M. Agostini, G. Greco, M. Cecchini. Sensors and Actuators B: Chemical, 254, 1–7 (2018)

Host: Giorgia Brancolini giorgia.brancolini@nano.cnr.it

[Ultimo aggiornamento: 01/04/2021 12:55:28]