Advances in glass Microfabrication. Femtosecond laser irradiation followed by chemical etching.

Author(s): VENTURINI F., SANSOTERA M., OSELLAME R., CERULLO G., NAVARRINI W.

Source: Chimica Oggi – Chemistry Today.

Volume: 30 Pages: 10-13. December (2012).

ABSTRACT:

Femtosecond laser irradiation followed by chemical etching (F.L.I.C.E.) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure attested in literature, which has been widely studied in the past years, consists of irradiating a glass slab and subsequently apply a chemical etching step. The results obtained by different research groups vary widely. In this paper we present a review of the most recent advancements of this technique discussing several critical factors that affect the aspect ratio, the length and the etching speed of the microchannel.

http://www.teknoscienze.com/Articles/Chimica-Oggi-Chemistry-Today-Advances-in-glass-Microfabrication-Femtosecond-laser-irradiation.aspx#.UouCWycUlZM

Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching.

Author(s): VENTURINI F., SANSOTERA M., VAZQUEZ R. M., OSELLAME R., CERULLO G., NAVARRINI W.

Sources: Micromachines

Volume: 3 (4) Pages: 604-614.

DOI:10.3390/mi3040604.

Published: Sept (2012).

ABSTRACT:

Femtosecond laser irradiation followed by chemical etching (FLICE) with hydrogen fluoride (HF) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure, as described in literature, consists of irradiating a silica slab followed by chemical etching using hydrogen fluoride. With aqueous HF the etching process is diffusion-limited and is self-terminating, leading to maximum microchannel lengths of about 1.5 mm, while the use of low-pressure gaseous HF etchant can quickly produce 3 mm long channels with an aspect ratio (Length/Diameter) higher than 25. By utilizing this methodology the aspect ratio is not constant, but depends on the length of the channel. When the microchannel is short the aspect ratio increases quickly until it reaches a maximum length at around 1400 um hereafter the aspect ratio starts to decrease slowly. In this paper we present a variation of the low-pressure gaseous HF etching method, which is based on the dynamic displacement of the etchant. This method results in a 13% increase in the aspect ratio (L/D = 29) at the expense of a low etching speed (4 um/min).

3rd Symposium on Continuous Flow Reactor Technology for Industrial Applications – October 2-4, 2011 – Como, Italy

Selective Iterative Etching of Fused Silica with Gaseous Hydrofluoric Acid.

Author(s): Venturini, Francesco; Navarrini, Walter; Resnati, Giuseppe; Metrangolo, Pierangelo; Vazquez, Rebeca Martinez; Osellame, Roberto; Cerullo, Giulio.

Source: JOURNAL OF PHYSICAL CHEMISTRY C

Volume: 114 Issue: 43 Pages: 18712-18716

DOI: 10.1021/jp107055s

Published: NOV 4 2010

ABSTRACT:

Femtosecond laser irradiation followed by chemical etching (FLICE) with hydrofluoric acid (HF) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels. With liquid HF, the etching process is diffusion-limited and is self-terminating, leading to maximum microchannel lengths of approximate to 1.5 mm. A strategy to overcome this limitation would be to perform iterative etching, periodically removing the exhausted products and replenishing the partially etched channel with fresh acid; this procedure is, however, quite cumbersome in the liquid phase. In this paper we present what is to our knowledge the first implementation of the FLICE technique with low-pressure gaseous HF etchant. The use of a gas-phase etchant naturally lends itself to the application of iterative etching techniques, since it is very easy to remove the etchant, by pumping vacuum in the reaction chamber after each etching step. We demonstrate that iterative etching in the gas phase overcomes the limitations of wet etching and allows to achieve nearly constant etching rate for a microchannel length up to approximate to 3 mm.

http://pubs.acs.org/doi/abs/10.1021/jp107055s

19th International Symposium on Fluorine Chemistry – Jackson Hole (USA) – August 23-28, 2009

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