Integrated sensor networks with error correction for multiplexed particle tracking in microfluidic chips.

Spatial manipulation of suspended cells based on their properties is an essential part of numerous microfluidic assays. To further read and analyze the manipulation result, a microscopy system is typically required, which, however, increases the cost and reduces the portability of the entire system. As an alternative, a network of integrated Coulter sensors, distributed over a microfluidic chip, provide rapid and reliable detection of spatially-manipulated cells. Code-multiplexing of distributed Coulter sensors enables simplification of such integration by offloading the hardware complexity into advanced signal processing techniques that are needed to interpret the coded sensor outputs. In this work, we combine code-multiplexed Coulter sensor networks with an error-correction technique, a strategy typically used in telecommunication systems for controlling errors in data over unreliable communication channels. Specifically, we include redundancy in the physical sensor design to alleviate the ambiguity in the signal-decoding process, so that interfering sensor signals due to coincidently-detected cells can be resolved reliably. The presented sensor technology not only tracks the spatiotemporal state of cells under test but also measures their sizes and flow speeds. To demonstrate the sensor concept experimentally, we fabricated a microfluidic device with 10 distributed Coulter sensors designed to produce distinct signal waveforms and performed experiments with suspended human cancer cells to characterize the performance of the sensor platform.