Generation of droplets for lab-on-a-piezoelectric-substrate utilizing surface acoustic wave

A method for a droplet transportation by jumping a obstacle on piezoelectric substrate is presented, and a device for the droplet transportation is implemented on a 128° yx-LiNbO3 piezoelectric substrate. An interdigital transducer and a reflector are fabricated on the piezoelectric substrate using microelectric technology. Hydrophobic film is coated on the area free of electrodes and a polydimethylsilicone obstacle is mounted on it. A radio frequency signal amplified by a power amplifier is applied to the interdigital transducer to generate surface acoustic wave. When the surface acoustic wave meets with the droplet on the piezoelectric substrate during transportation, part of acoustic wave enegy is radiated into the droplet, leading to internal acoustic streaming. Once the radio frequency signal with appropriate amplitude is suddenly decreased, part of the droplet will jump the obstacle due to interial force. Red dye solution drops are demonstrated for transportation experiments. Results show that a droplet can be transported from one side to another of the obstacle on piezoelectric substrate by help of surface acoustic wave. The presented method is helpful for microfluidic system on a piezoelectric substrate.

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Paper Based Microfluidic Device Using Surface Acoustic Wave as Driving Source

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.1658 ◽

2011 ◽

Vol 130-134 ◽

pp. 1658-1662

Author(s):

An Liang Zhang ◽

Qing Jiang Han

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Chemical Reaction ◽

Microfluidic Device ◽

Filter Paper ◽

Microfluidic System ◽

Analyte Concentration ◽

Interdigital Transducer ◽

Driving Source ◽

Piezoelectric Substrate

It is necessary to implement pretreatment operations for a paper based microfluidic device. A paper based microfluidic device with SAW driving microfluid has been implemented. Trance analyte to be detected was absorbed into a filter paper at first, and mounted on PDMS blocks on a piezoelectric substrate to ensure that the indicting filter paper has a little gap with the piezoelectric substrate. Reagents were then pipetted on the piezoelectric substrate and transported by surface acoustic wave excited by an interdigital transducer, which was fabricated on a 1280-yx LiNbO3 using micro-electrical technology. A color was developed due to chemical reaction, and the analyte concentration was evaluated by its grey value. Nitrate ion was detected using the microfluidic system.

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Splitting Drops on a Piezoelectric Substrate by Help of Surface Acoustic Wave

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.336-338.80 ◽

2013 ◽

Vol 336-338 ◽

pp. 80-83

Author(s):

Ai Liang Zhang ◽

Xiang Ting Fu ◽

Yan Zha

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Biochemical Analysis ◽

Acoustic Streaming ◽

Microfluidic System ◽

Preparation Technique ◽

Sample Preparation Technique ◽

Interdigital Transducer ◽

Red Dye ◽

Piezoelectric Substrate

A new method for splitting drops on a piezoelectric substrate is presented. An interdigital transducer with the period of 144μm is fabricated on a 128° yx-LiNbO3piezoelectric substrate using microelectric technology. Intermittent surface acoustic wave is generated by an on-to-off radio frequency signal, which is applied to the interdigital transducer, and then radiates into a drop on the acoustic path of the piezoelectric substrate, leading to discontinuous acoustic streaming. A part of the drop is split due to inertia when the surface acoustic wave is suddenly disappeared. Red dye solution drops are demonstrated for fission experiments, and mixture operation of two drops is also implemented using the fission method. Results show that a drop can be split by help of surface acoustic wave, and the distance of two daughters is determined on the volume of the drop. The presented drop fission method provides a new sample preparation technique, which is helpful for microfluidic biochemical analysis in a microfluidic system.

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Transportation of Droplets within Two Substrates by Help of Surface Acoustic Wave

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.160.92 ◽

2012 ◽

Vol 160 ◽

pp. 92-96

Author(s):

An Liang Zhang ◽

Yan Zha

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Biochemical Analysis ◽

Good Option ◽

New Method ◽

Curvature Radius ◽

Hydrophobic Property ◽

Red Dye ◽

Piezoelectric Substrate

It is usually difficult to integrate all operation units of complicated biochemical analysis systems into a micro-fluidic substrate. A multi substrate micro-fluidic system (MSMS) is a good option, in which operation units can be integrated into two or more substrates. Thus, it is necessary to transport droplets between two substrates. In this paper, a new method for transporting droplets between two substrates has been proposed based on surface acoustic wave (SAW). It is composed of a 128°YX-LiNbO3 piezoelectric substrate (substrate 1) and an arc-shaped polymer. The arc-shaped polymer is seamlessly adhered to the piezoelectric substrate, and the lowest end is above another a substrate (substrate 2) with some distances. After a droplet in the substrate 1 is propelled to the arc-shaped polymer by SAW, it will slide off the polymer due to its gravity, and transported onto the substrate 2. Theoretical formulas of forces acted on the droplet have been deduced and the condition of the droplet sliding off the arc-shaped has also been obtained. Red dye solution droplets were used in the transporting experiments. Results show that the transportation of droplets is decided on curvature radius and hydrophobic property of the arc-shaped polymer and the droplet volumes. As applications, mixture operations have been implemented in substrate 2 after droplets have been transported from the substrate 1.

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