A versatile technology platform for microfluidic handling systems, part II: channel design and technology

Abstract

integrated devices. The channels can be freely suspended, and top-side, bottom-side and in-plane fluidic interfacing is possible. Transducer structures can be integrated in close proximity to the fluid using suitable materials. In these microfluidic handling systems, many different microfluidic devices can be integrated on the same chip. As a result, these devices are connected with very small internal volumes which allows for fast response times and handling of small sample sizes. Several options are proposed to add functionality to the devices. Some examples of these are: metalization, release of the channels from the bulk or a buried oxide layer to mechanically or electrically isolate parts of the chip or provide buried fluidic channels.In this paper, we discuss several channel etching methods and look at their applicability in the platform. The full fabrication process is discussed in Groenesteijn et al. (2017). The channels are etched isotropically through etch slits in a silicon-rich silicon nitride layer on top of the wafer. As a result, the size and shape of the channels can be tuned to meet the demands of any application. Here, we propose a method, based on an empirical etch model, to design the slit pattern that will result in the desired channel shape.In Sect. 4, the channel design of an integrated microfluidic handling system with multiple fluidic sensors is discussed. Fabrication outlineThe fabrication of the devices can be roughly divided into three main steps: fabrication of the microchannels, fabrication of the functional structures and fabrication of the fluidic access to the channels. In this section, an outline of the fabrication process is given where channels are etched at Abstract Microfluidic devices often require channels of a specific size and shape. These devices are then made in a fabrication process that is often specialized to produce only those (and very similar) channels. As a result, devices requiring channels of different size and shape cannot easily be integrated on the same chip. This paper presents a method to fabricate microfluidic channels in a wide range of shape and size on the same chip by using a slit pattern through which the channels are etched. The fabrication process to fabricate these channels is discussed in detail, and an empirical model is presented to find the optimal slit pattern for a required size and shape. This part of the paper focusses on the channel design and fabrication. Details on the whole fabrication process and optional functionalization of the channels are presented in part I of this paper.

A versatile technology platform for microfluidic handling systems, part I: fabrication and functionalization

“…Using many slits close together will result in a deep, round channel, while many slits spaced far apart will result in a wide, shallow cavity. The relation between the slit pattern and the resulting channel dimensions is discussed in a separate paper (Groenesteijn et al 2017).…”

“…The location and density of the slits determine the shape and size of the channels that are etched through them and is discussed in detail in a separate paper. Groenesteijn et al (2017) Note that in the figures, in the left column, the slits are spaced far apart, while in the middle and right column, sets of slits are placed close together. This will result in channels of different sizes.…”

“…The different devices that are integrated and the required functionalization steps are discussed. The designs are made using the channel-etch model described in Groenesteijn et al (2017). Details of the devices and measurement results of these systems are shown in the cited papers.…”

“…While most applications have been presented before, this is the first time that the platform itself is presented in detail. As part of the platform, in Groenesteijn et al (2017) we will present a method to find the right channel design for the required channels and discuss the fabrication of the channels in detail.…”

Integrated throughflow mechanical microfluidic sensors

“…Also research has been done on micro bypasses for pressure drop reduction [63] and resolution improvements [64]. The fabrication method has also been developed further [65,66], with support for proportional valves [67] and other microfluidic structures. An extensive overview can be found in [68].…”