Afg3011c

Both acoustofluidic devices were driven by sinewave signals from Tektronix AFG3011C function generator. IDTs-based acoustofluidic enrichment device was mounted on the stage of an inverted microscope (Eclipse Ti-U, Nikon, Japan), which is equipped with a CCD camera for recording the motion of the particles inside the glass capillary. For the acoustofluidic sharp-edge mixer device, the reagents were delivered to the microchannels by BD Bioscience syringes, which were operated by an external automated neMESYS syringe pump.

The acoustic transducer was driven by sinewave signals supplied from a
function generator (AFG3011C, Tektronix, USA) with an applied voltage and
frequency of 10 V and 4.3 kHz, respectively. The reagents were delivered to the
inlets of PDMS microchannel by 1 mL syringes (BD Bioscience, NJ), which were
independently operated by an external automated syringe pump (neMESYS, Cetoni,
Germany). The mixing videos were recorded on the stage of an inverted microscope
(Eclipse Ti-U, Nikon, Japan) and then processed with ImageJ
software (NIH, Bethesda, MD) for making the stacked images.

Every experiment was conducted on a microscope (TE2000-U, Nikon, Japan). Individual C. elegans were stably injected into the microchannel through 1 mL syringes (BD Bioscience, USA) administered by an automated syringe pump (neMESYS, Germany). A function generator (AFG3011C, Tektronix, USA) and an amplifier (25A250A, Amplifier Research, USA) were used to drive the IDTs. The resonant frequency of the device was first identified using a network analyzer (Vector Network Analyzer 2180, Array Solutions, USA). Upon identifying the resonant frequency, we then compared the acoustic streaming intensity in the microchannel within a frequency range (±1 MHz) around the resonant frequency at the same amplitude. An optimal driving frequency of 19.32 MHz was chosen because at this frequency the IDTs generated the strongest acoustic streaming in the microchannel. Images and videos were captured by a fast camera (Fastcam SA4, Photron, USA) through Photron FASTCAM Viewer (PFV, Photron, USA). A Nikon filter cube (excitation: 470 nm; emission: 515 nm), a CCD digital camera (CoolSNAP HQ2, Photometrics, USA), and a fiber optic illumination system (Intensilight, Nikon, Japan) were used to record the fluorescent images and videos. All acquired images and videos were analyzed by ImageJ (NIH, USA).

The device was designed to allow cells suspended in DEP buffer to flow through the channels and be attracted to the BPE tips in pDEP mode. AC voltage to drive the DEP response was applied to the driving electrodes (outer rows of electrodes) using a Tektronix AFG3011C waveform generator (Tektronix, Beaverton, OR) and Trek model 2205 amplifier (Trek, Lockport, NY). The AC frequency was maintained at 70 kHz to ensure the MDA-MB-231 cells experienced strong pDEP, based on crossover frequencies (25-50 kHz) reported by Shim et al.^{21 (link)} and corroborated by our previous work.^{22 (link)} The devices were imaged using a Nikon AZ100 microscope (Nikon, Tokyo, Japan). Flow was induced using a Pico Plus Elite syringe pump (Harvard Apparatus, Holliston, MA) paired with a 500 μL glass syringe (Hamilton Company, Reno, NV) in withdrawal mode. Cell counting was assisted through labeling of a cell surface antigen (EpCAM) with a phycoerythrin-linked antibody (PE/anti-EpCAM). The resolution of these fluorescence images, obtained over the entire array, is too low to determine cell volume. Higher resolution micrographs were obtained during DEP capture for limited sections of the array. Since cell volume influences the total quantity of enzyme contained in each cell, strategies for rapidly and accurately determining cell volume through imaging will be pursued in our future work.