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Sacrificial adhesive bonding: a powerful method for fabrication of glass microchips.

Lima RS, Leão PA, Piazzetta MH, Monteiro AM, Shiroma LY, Gobbi AL, Carrilho E - Sci Rep (2015)

Bottom Line: This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests.Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature.Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Microfabricação, Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil.

ABSTRACT
A new protocol for fabrication of glass microchips is addressed in this research paper. Initially, the method involves the use of an uncured SU-8 intermediate to seal two glass slides irreversibly as in conventional adhesive bonding-based approaches. Subsequently, an additional step removes the adhesive layer from the channels. This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests. Named sacrificial adhesive layer (SAB), the protocol meets the requirements of an ideal microfabrication technique such as throughput, relatively low cost, feasibility for ultra large-scale integration (ULSI), and high adhesion strength, supporting pressures on the order of 5 MPa. Furthermore, SAB eliminates the use of high temperature, pressure, or potential, enabling the deposition of thin films for electrical or electrochemical experiments. Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature. Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives.

No MeSH data available.


Related in: MedlinePlus

Effect of the remaining SU-8 layer on the surface properties of the microfluidic channel.The Ohm’s law plots were obtained by using 20 mmol L−1 phosphate at pH 8.0 for glass (yellow) and glass/SU-8/glass (red) microdevices. Each value represents a global average current which was achieved from four microchips (real-time monitoring for 2 min).
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f8: Effect of the remaining SU-8 layer on the surface properties of the microfluidic channel.The Ohm’s law plots were obtained by using 20 mmol L−1 phosphate at pH 8.0 for glass (yellow) and glass/SU-8/glass (red) microdevices. Each value represents a global average current which was achieved from four microchips (real-time monitoring for 2 min).

Mentions: Under the same ionic strength conditions, the glass and SU-8 surfaces generate similar electroosmotic mobility26 and electrokinetic experiments were not necessary to study the effect of the SU-8 on the channel surface properties. Conversely, the thermal conductivity values for SU-8 and glass are 0.2 and 1.5 W mK−1, respectively. It yields a substantial difference in the heat dissipation capacity for glass and glass/SU-8 walls. Analyses with 20 mmol L−1 phosphate buffer at pH 8.0 showed some Joule heating with linearity deviation in the current/potential relationship at electric fields higher than 580 and 730 V cm−1 for microfluidic channels of glass/SU-8 and glass, respectively21. Under such conditions, chips obtained by SAB had similar thermal behaviour when compared to glass, as illustrated in the Ohm’s law plots of Fig. 8. In both cases, Joule heating was observed only at electric fields greater than 730 V cm−1. This data indicates that the residual layers of SU-8 after the SAB did not interfere on surface properties of the glass channel walls.


Sacrificial adhesive bonding: a powerful method for fabrication of glass microchips.

Lima RS, Leão PA, Piazzetta MH, Monteiro AM, Shiroma LY, Gobbi AL, Carrilho E - Sci Rep (2015)

Effect of the remaining SU-8 layer on the surface properties of the microfluidic channel.The Ohm’s law plots were obtained by using 20 mmol L−1 phosphate at pH 8.0 for glass (yellow) and glass/SU-8/glass (red) microdevices. Each value represents a global average current which was achieved from four microchips (real-time monitoring for 2 min).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543966&req=5

f8: Effect of the remaining SU-8 layer on the surface properties of the microfluidic channel.The Ohm’s law plots were obtained by using 20 mmol L−1 phosphate at pH 8.0 for glass (yellow) and glass/SU-8/glass (red) microdevices. Each value represents a global average current which was achieved from four microchips (real-time monitoring for 2 min).
Mentions: Under the same ionic strength conditions, the glass and SU-8 surfaces generate similar electroosmotic mobility26 and electrokinetic experiments were not necessary to study the effect of the SU-8 on the channel surface properties. Conversely, the thermal conductivity values for SU-8 and glass are 0.2 and 1.5 W mK−1, respectively. It yields a substantial difference in the heat dissipation capacity for glass and glass/SU-8 walls. Analyses with 20 mmol L−1 phosphate buffer at pH 8.0 showed some Joule heating with linearity deviation in the current/potential relationship at electric fields higher than 580 and 730 V cm−1 for microfluidic channels of glass/SU-8 and glass, respectively21. Under such conditions, chips obtained by SAB had similar thermal behaviour when compared to glass, as illustrated in the Ohm’s law plots of Fig. 8. In both cases, Joule heating was observed only at electric fields greater than 730 V cm−1. This data indicates that the residual layers of SU-8 after the SAB did not interfere on surface properties of the glass channel walls.

Bottom Line: This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests.Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature.Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Microfabricação, Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil.

ABSTRACT
A new protocol for fabrication of glass microchips is addressed in this research paper. Initially, the method involves the use of an uncured SU-8 intermediate to seal two glass slides irreversibly as in conventional adhesive bonding-based approaches. Subsequently, an additional step removes the adhesive layer from the channels. This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests. Named sacrificial adhesive layer (SAB), the protocol meets the requirements of an ideal microfabrication technique such as throughput, relatively low cost, feasibility for ultra large-scale integration (ULSI), and high adhesion strength, supporting pressures on the order of 5 MPa. Furthermore, SAB eliminates the use of high temperature, pressure, or potential, enabling the deposition of thin films for electrical or electrochemical experiments. Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature. Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives.

No MeSH data available.


Related in: MedlinePlus