5.1 Problem Description and Proposed Approach
65
Especially the fluidic resistance of the meander is important as it impacts the
flow state (i.e., the pressure-flow relation). Recall, the fluidic resistance R for a
(meander) channel with a rectangular cross section depends on its length l, width w,
height h, and the viscosity μ of the fluid passing through and is defined by Eq. 3.2
(cf. page 24). Besides embodying a particular resistance value, a meander needs
to comply with specific design rules and ideally make full use of a given chip
space while providing needed connectivity to the rest of the design. Designing a
meander with a desired fluidic resistance and additionally considering all those
constraints makes the design a cumbersome task. For example, already a slight
change in the length of the meander significantly affects the desired resistance
(cf. Eq. 3.2).
In an effort to automate this task (and, by this, to aid the designer), this chapter
proposes a method, which allows to automatically generate meander designs for
the designer’s specific needs and constraints. Therefore, the designer only has to
provide
• the desired resistance,
• the viscosity of the used fluid,
• the desired width/height ratio of the meander boundary,
• the channel width and height (information of the channel cross section),
• the fabrication constraints such as a lateral channel distance and a minimum bend
radius,
• the inlet and outlet positions, as well as
• an optional correction factor in the form of a constant or first-order function.
Using this input, the proposed method generates a meander design in a fully
automatic fashion. This includes
• the meander design as a Scalable Vector Graphics (SVG) file (which is supported
by all commonly used design tools),
• the resulting channel length,
• the resulting channel volume,
• the resulting boundary size of the meander (the width and height), as well as
• the logging file, which serves as a documentation of the generated meander.
Furthermore, the method allows to account for actual and non-ideal fabrication
results in the form of a correction factor. For example, in the process of soft
lithography, the fabrication result, e.g., of the channel width depends on a variety of
parameters. Main influences are the photomask, the exposure step, the development
step, and various tempering steps. The channel height also underlies variation
due to coating, tempering, and development steps. Therefore, the fabrication
result can vary and depends on a series of influences. This complexity of dependent and independent influences makes it difficult to account for in the design
process.
65
Especially the fluidic resistance of the meander is important as it impacts the
flow state (i.e., the pressure-flow relation). Recall, the fluidic resistance R for a
(meander) channel with a rectangular cross section depends on its length l, width w,
height h, and the viscosity μ of the fluid passing through and is defined by Eq. 3.2
(cf. page 24). Besides embodying a particular resistance value, a meander needs
to comply with specific design rules and ideally make full use of a given chip
space while providing needed connectivity to the rest of the design. Designing a
meander with a desired fluidic resistance and additionally considering all those
constraints makes the design a cumbersome task. For example, already a slight
change in the length of the meander significantly affects the desired resistance
(cf. Eq. 3.2).
In an effort to automate this task (and, by this, to aid the designer), this chapter
proposes a method, which allows to automatically generate meander designs for
the designer’s specific needs and constraints. Therefore, the designer only has to
provide
• the desired resistance,
• the viscosity of the used fluid,
• the desired width/height ratio of the meander boundary,
• the channel width and height (information of the channel cross section),
• the fabrication constraints such as a lateral channel distance and a minimum bend
radius,
• the inlet and outlet positions, as well as
• an optional correction factor in the form of a constant or first-order function.
Using this input, the proposed method generates a meander design in a fully
automatic fashion. This includes
• the meander design as a Scalable Vector Graphics (SVG) file (which is supported
by all commonly used design tools),
• the resulting channel length,
• the resulting channel volume,
• the resulting boundary size of the meander (the width and height), as well as
• the logging file, which serves as a documentation of the generated meander.
Furthermore, the method allows to account for actual and non-ideal fabrication
results in the form of a correction factor. For example, in the process of soft
lithography, the fabrication result, e.g., of the channel width depends on a variety of
parameters. Main influences are the photomask, the exposure step, the development
step, and various tempering steps. The channel height also underlies variation
due to coating, tempering, and development steps. Therefore, the fabrication
result can vary and depends on a series of influences. This complexity of dependent and independent influences makes it difficult to account for in the design
process.