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Conventional strategies for biological sensing require complex workflows to capture, isolate, and prepare biomolecules for specific and high-sensitivity detection. Instruments that facilitate these processes are usually cumbersome, reducing user-friendliness and accessibility. Here, we present a multichannel acoustic separator with biospecific and acoustically responsive microparticles to simplify workflows and shorten the time needed to isolate and detect biomarkers from complex fluids. The multichannel acoustic separator is 3D-printed and supports 12 acoustofluidic trapping channels that isolate the biospecific particles from off-target contaminants in the fluid. Fluid flow through the channels is driven by a semi-continuous siphon, which eliminates the need for fluid pumps. We tested the system for purifying three disparate biomolecules in individual and multiplexed formats, as well as the purification of IgA from whole blood for detection in approximately 70 min. 

Most biosensing techniques require complex processing steps that generate prolonged workflows and introduce potential points of error. Here, we report an acoustic pipette to purify and label biomarkers in 70 minutes. A key aspect of this technology is the use of functional negative acoustic contrast particles (fNACPs), which display biorecognition motifs for the specific capture of biomarkers from whole blood. Because of their large size and compressibility, the fNACPs robustly trap along the pressure antinodes of a standing wave and separate from blood components in under 60 seconds with >99% efficiency. fNACPs are subsequently fluorescently labeled in the pipette and are analyzed by both a custom, portable fluorimeter and flow cytometer. We demonstrate the detection of anti-ovalbumin antibodies from blood at picomolar levels (35 to 60 pM) with integrated controls showing minimal nonspecific adsorption. Overall, this system offers a simple and versatile approach for the rapid, sensitive, and specific capture of biomolecules. 

Active particles, or micromotors, locally dissipate energy to drive locomotion at small length scales. The type of trajectory is generally fixed and dictated by the geometry and composition of the particle, which can be challenging to tune using conventional fabrication procedures. Here, we report a simple, bottom-up method to magnetically assemble gold-coated polystyrene Janus particles into “locked” clusters that display diverse trajectories when stimulated by AC electric fields. The orientation of particles within each cluster gives rise to distinct modes of locomotion, including translational, rotational, trochoidal, helical, and orbital. We model this system using a simplified rigid beads model and demonstrate qualitative agreement between the predicted and experimentally observed cluster trajectories. Overall, this system provides a facile means to scalably create micromotors with a range of well-defined motions from discrete building blocks.