Assembly and Characterization of an External Driver for the Generation of Sub-Kilohertz Oscillatory Flow in Microchannels

摘要

The protocol demonstrates a convenient method to produce harmonic oscillatory flow from 10-1000 Hz in microchannels. This is performed by interfacing a computer-controlled speaker diaphragm to the microchannel in a modular manner.

摘要

Microfluidic technology has become a standard tool in chemical and biological laboratories for both analysis and synthesis. The injection of liquid samples, such as chemical reagents and cell cultures, is predominantly accomplished through steady flows that are typically driven by syringe pumps, gravity, or capillary forces. The use of complementary oscillatory flows is seldom considered in applications despite its numerous advantages as recently demonstrated in the literature. The significant technical barrier to the implementation of oscillatory flows in microchannels is likely responsible for the lack of its widespread adoption. Advanced commercial syringe pumps that can produce oscillatory flow, are often more expensive and only work for frequencies less than 1 Hz. Here, the assembly and operation of a low-cost, plug-and-play type speaker-based apparatus that generates oscillatory flow in microchannels is demonstrated. High-fidelity harmonic oscillatory flows with frequencies ranging from 10-1000 Hz can be achieved along with independent amplitude control. Amplitudes ranging from 10-600 µm can be achieved throughout the entire range of operation, including amplitudes > 1 mm at the resonant frequency, in a typical microchannel. Although the oscillation frequency is determined by the speaker, we illustrate that the oscillation amplitude is sensitive to fluid properties and channel geometry. Specifically, the oscillation amplitude decreases with increasing channel circuit length and liquid viscosity, and in contrast, the amplitude increases with increasing speaker tube thickness and length. Additionally, the apparatus requires no prior features to be designed on the microchannel and is easily detachable. It can be used simultaneously with a steady flow created by a syringe pump to generate pulsatile flows.

引言

The precise control of liquid flow rate in microchannels is crucial for lab-on-a-chip applications such as droplet production and encapsulation¹, mixing^2,3, and the sorting and manipulation of suspended particles^4,5,6,7. The predominantly used method for flow control is a syringe pump that produces highly controlled steady flows dispensing either a fixed volume of liquid or a fixed volumetric flow rate, often limited to entirely unidirectional flow. Alternativ....

方案

1. Rapid prototype mold design and fabrication

1. Open AutoCAD on a PC. Select File on the taskbar, then select Open and browse to and click on a three-dimensional (3D) model file of the channel mold having .dxf or .dwg extension.
2. Select the entire model by clicking and dragging a box around it. Export the design as a .stl file by selecting File | Export, then Other formats and choosing .stl from the dropdown box.
3. Upload the file to a high precision resin stereolithographic (SLA) printer such as Formlabs FORM3. Pour the resin into the resin chamb....

结果

To illustrate the capability and performance of the above setup, representative results of oscillatory flow in a simple linear microchannel with a square cross-section are presented. The width and height of the channel are 110 µm and its length is 5 cm. First, we describe the motion of spherical polystyrene tracer particles and how these can be used to check the fidelity of the oscillatory signal as well as the range of oscillation amplitudes achievable. We then discuss the effect of specific fluid properties or microflu.......

讨论

We have demonstrated the assembly (see protocol critical steps 3 and 4) and operation (see protocol critical steps 5 and 6) of an external speaker-based apparatus for the generation of oscillatory flow with frequencies in the range of 10 to 1000 Hz in microfluidic devices. Particle tracking of suspended tracer particles is required to determine the fidelity of the harmonic motion as well as for calibrating the range of oscillation amplitudes achievable over the range of operating frequencies. The amplitude-frequency curv.......

材料

本文使用的材料清单

姓名	公司	目录编号	评论
<强>振荡驱动器组件
鳄鱼对针线	Adafruit	3255	小鳄鱼夹到公跳线 （12）
辅助电缆	Adafruit	2698	3.5 毫米公/公立体声电缆 1 m
控制器芯片	Damgoo	TPA3116	50w+50w 2 通道音频放大器（蓝牙和 AUX）
直流适配器	Adafruit	798	12 V DC 1A 稳压开关电源适配器
微量移液器吸头	VWR Signature	37001-532	200 ul 微量移液器吸头
硅酮密封剂	Loctite	908570	透明硅胶防水密封剂 （80 ml）
扬声器	Drok	6843996	4.5 英寸 4 欧姆 40 W 扬声器
扬声器支架			从补充文件中的"speakermount.stl"3D 打印
补充文件中的"speaketubeadapter.stl"3D 打印	扬声器到电子管适配器
微通道制造
活检打孔器	Miltex	15110	带柱塞的活检打孔器 （1 - 4 mm）
脱气机
一次性杯子
一次性勺子
玻璃滑轨	VWR Signature	16004-430	3" x 1" 预清洁 1 毫米厚
模具			Si - SU-8 或 3D 打印
	Oven Fischer Scientific		Isotemp
PDMS 树脂和交联剂	Dow Chemical	4019862	Sylgard 184 PDMS 树脂和交联剂 （500 g）
聚乙烯管	Becton Dickinson Intramedic	427440	聚乙烯管 （PE 60 - PE 200）
剃须刀片	VWR	55411-050	单刃工业剃须刀片
射频等离子发生器	Electro-Technic Products	BD - 20	高频发生器
硅胶脱模	CRC	03301	食品级硅脱模剂（16盎司）
<强>观察和表征
相机	Edgertronic		SC2+
镜头	尼康		Plan Fluor 10x
显微镜	尼康		Ti Eclipse手动舞台
针	Becton Dickinson	305175	PrecisionGlide 20G
注射器	Becton Dickinson	1180100555	Monoject 1 ml
注射泵	Harvard Apparatus		双注射器可编程注射泵
示踪颗粒	Spherotech	PP-10-10	聚苯乙烯示踪颗粒 1 um