Self-transport and self-alignment of microchips using microscopic rain

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© 2015 Nature Publishing Group. This is the accepted version of the following article: Chang, Bo & Shah, Ali & Zhou, Quan & Ras, Robin & Hjort, Klas. 2015. Self-transport and self-alignment of microchips using microscopic rain. Scientific Reports 5. 14966/1-8. DOI: 10.1038/srep14966, which has been published in final form at http://www.nature.com/articles/srep14966.
Final published version

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Journal Title

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Volume Title

School of Electrical Engineering | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2015

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Mcode

Degree programme

Language

en

Pages

14966/1-8

Series

Scientific Reports 5

Abstract

Alignment of microchips with receptors is an important process step in the construction of integrated micro- and nanosystems for emerging technologies, and facilitating alignment by spontaneous self-assembly processes is highly desired. Previously, capillary self-alignment of microchips driven by surface tension effects on patterned surfaces has been reported, where it was essential for microchips to have sufficient overlap with receptor sites. Here we demonstrate for the first time capillary self-transport and self-alignment of microchips, where microchips are initially placed outside the corresponding receptor sites and can be self-transported by capillary force to the receptor sites followed by self-alignment. The surface consists of hydrophilic silicon receptor sites surrounded by superhydrophobic black silicon. Rain-induced microscopic droplets are used to form the meniscus for the self-transport and self-alignment. The boundary conditions for the self-transport have been explored by modeling and confirmed experimentally. The maximum permitted gap between a microchip and a receptor site is determined by the volume of the liquid and by the wetting contrast between receptor site and substrate. Microscopic rain applied on hydrophilic-superhydrophobic patterned surfaces greatly improves the capability, reliability and error-tolerance of the process, avoiding the need for accurate initial placement of microchips, and thereby greatly simplifying the alignment process.

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Keywords

microassembly, self-alignment, self-transport, self-assembly

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Citation

Chang, Bo & Shah, Ali & Zhou, Quan & Ras, Robin & Hjort, Klas. 2015. Self-transport and self-alignment of microchips using microscopic rain. Scientific Reports 5. 14966/1-8. DOI: 10.1038/srep14966.