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Arbitrary patterning of micro-objects in liquid is crucial to many biomedical applications. Among conventional methodologies, acoustic approaches provide superior biocompatibility but are intrinsically limited to producing periodic patterns at low resolution due to the nature of standing waves and the coupling between fluid and structure vibrations. This work demonstrates a near-field acoustic platform capable of synthesizing high resolution, complex and non-periodic energy potential wells. A thin and viscoelastic membrane is utilized to modulate the acoustic wavefront on a deep, sub-wavelength scale by suppressing the structural vibration selectively on the platform. Using 3 MHz excitation ( λ ∼ 500 μm in water), we have experimentally validated such a concept by realizing patterning of microparticles and cells with a line resolution of 50 μm (one tenth of the wavelength). Furthermore, massively parallel patterning across a 3 × 3 mm 2 area has been achieved. This new acoustic wavefront modulation mechanism is powerful for manufacturing complex biologic products. 

We developed a highly efficient method for patterning cells by a novel and simple technique called lift-off cell lithography (LCL). Our approach borrows the key concept of lift-off lithography from microfabrication and utilizes a fully biocompatible process to achieve high-throughput, high-efficiency cell patterning with nearly zero background defects across a large surface area. Using LCL, we reproducibly achieved >70% patterning efficiency for both adherent and non-adherent cells with <1% defects in undesired areas. 

We report a novel manufacturing approach to fabricate liquid metal-based, multifunctional microcapillary pipettes able to provide electrodes with high electrical conductivity for high frequency electrical stimulation and measurement. Four-dimensional single cell manipulation has been realized by applying multi-frequency, multi-amplitude, and multi-phase electrical signals to the microelectrodes near the pipette tip to create a 3D dielectrophoretic trap and 1D electrorotation simultaneously. Functions such as single cell trapping, transferring, patterning, and rotation have been accomplished. Cell viability and multi-day proliferation characterization has confirmed the biocompatibility of this approach. This is a simple, low cost, and fast fabrication approach that requires no cleanroom and photolithography to manufacture 3D microelectrodes and microchannels accessible to a wide user base for broad applications.