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A novel design based on electric field-free open microwell arrays for the automated continuous-flow sorting of single or small clusters of cells is presented. The main feature of the proposed device is the parallel analysis of cell-cell and cell-particle interactions in each microwell of the array. High throughput sample recovery with a fast and separate transfer from the microsites to standard microtiter plates is also possible thanks to the flexible printed circuit board technology which permits to produce cost effective large area arrays featuring geometries compatible with laboratory equipment. The particle isolation is performed via negative dielectrophoretic forces which convey the particles’ into the microwells. Particles such as cells and beads flow in electrically active microchannels on whose substrate the electrodes are patterned. The introduction of particles within the microwells is automatically performed by generating the required feedback signal by a microscope-based optical counting and detection routine. In order to isolate a controlled number of particles we created two particular configurations of the electric field within the structure. The first one permits their isolation whereas the second one creates a net force which repels the particles from the microwell entrance. To increase the parallelism at which the cell-isolation function is implemented, a new technique based on coplanar electrodes to detect particle presence was implemented. A lock-in amplifying scheme was used to monitor the impedance of the channel perturbed by flowing particles in high-conductivity suspension mediums. The impedance measurement module was also combined with the dielectrophoretic focusing stage situated upstream of the measurement stage, to limit the measured signal amplitude dispersion due to the particles position variation within the microchannel. In conclusion, the designed system complies with the initial specifications making it suitable for cellomics and biotechnology applications.

We present the development and application of a microfluidic device that can efficiently and reproducibly isolate a programmable number of cells into microwells. The chip consists of a 3x4 array of 100 µm microwells drilled through a flex-PCB substrate along microchannels. Negative DEP focusing of particles is used to axially centre particles within the channel and also to shield the microwell entrance for flowing particles. An optical detection routine analyses and selects the cells to be delivered with single cell resolution. Cell viability results based on a calcein release assay performed on single cells are within the range of physiological loss of fluorescence intensity.

We present a novel method for the isolation, functional analysis and sorting of single cells or small cellular aggregates. In- verted open microwells featuring a microchannel on top, an open air-fluid interface on bottom side and embedded electrodes were implemented on flexible-PCB technology. Microwell arrays in pitch with standard microtiter plates were implemented. K562 cells were delivered to the microwells and trapped at the air-flow interface. Cell delivery and aggregate formation were controlled by dielectrophoresis. Continuous fluid replacement around the cells during the experiment was demonstrated. After analysis, live cells were easily recovered to standard plates where cell growth was demonstrated.

We present here an innovative architecture based on negative-dielectrophoresis (nDEP) to perform the controlled isolation and patterning of a programmable number of cells inside microwells. The high efficiency solution we propose features electrodes placed on the floor and sidewalls of the microfluidic channels where microwells are realized and allows for the successful isolation, patterning and live-cell imaging of both single cells and cell clusters, with single cell resolution. Cell viability was assessed after delivery performing a calcein release assay in the microwells.

In this work we present a method for delivering small fluid volumes possibly containing cells and particles over a flexible large area substrate. Particles are deposited by a dispensing device that performs serial delivery of liquid volumes in the range of 200 pL. Due to the required precision, the alignment and the calibration of the spotting system are crucial for the proper performance of the delivery process. The system provides automated motion of mechanical parts with micrometric precision. To address the problem of the device deformation caused by the flexibility of the substrate, the 3D coordinates of each site need to be known, but the serial acquisition of all the coordinates would be highly time consuming for high-throughput arrays and large devices. We solved this problem by sampling the coordinates of a small subset and interpolating the positions of the remaining sites by means of a custom algorithm. System calibration for%2