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36 PCB007 MAGAZINE I NOVEMBER 2018 by Kenna Simmons, Georgia Institute of Technology Researchers from the Georgia Institute of Technology have designed a cellular interfac- ing array using low-cost electronics that mea- sures multiple cellular properties and respons- es in real time. This could enable more poten- tial drugs to be comprehensively tested for effi- cacy and toxic effects much faster. Hua Wang, associate professor in the School of Electrical and Computer Engineering at Georgia Tech, describes it as "helping us find the golden nee- dle in the haystack." Pharmaceutical companies use cell-based as- says—a combination of living cells and sensor electronics—to measure physiological changes in the cells. That data is used for high-through- put screening (HTS) during drug discovery. In this early phase of drug development, the goal is to identify target pathways and promising chem- ical compounds that could be developed further and to eliminate those that are ineffective or tox- ic, by measuring the physiological responses of the cells to each compound. Phenotypic test- ing of thousands of candidate compounds with the majority failing early allows only the most promising ones develop into drugs and undergo clinical trials where drug failure is much more costly. However, most existing cell-based assays use electronic sensors that can only measure one physiological property at a time and cannot obtain holistic cellular responses. That's where the new cellular sensing plat- form comes in. "The innovation of our technol- ogy is that we are able to leverage the advance of nanoelectronic technologies to create cellu- lar interfacing platforms with massively paral- lel pixels," said Wang, "Within each pixel, we can detect multiple physiological parameters from the same group of cells at the same time." The experimental quad-modality chip features extracellular or intracellular potential recording, optical detection, cellular impedance measure- ment, and biphasic current stimulation. Wang said the new technology offers four advantages over existing platforms: 1. Multimodal sensing: The chip's ability to re- cord multiple parameters on the same cellular sample gives researchers the ability to compre- hensively monitor complex cellular responses, uncover the correlations among those parame- ters, and investigate how they may respond to- gether when exposed to drugs. 2. Large field of view: The platform allows re- searchers to examine the behavior of cells in a large aggregate to see how they respond collec- tively at the tissue level. 3. Small spatial resolution: Researchers can look at cells at the tissue level and examine them at single-cell or even sub-cellular reso- lution. 4. Low-cost platform: The new array platform is built on standard complementary metal ox- ide semiconductor (CMOS) technologies— which is also used to build computer chips— and can be easily scaled up for mass produc- tion. Wang's team worked closely with Hee Che- ol Cho, associate professor and the Urowsky- New Chip Measures Multiple Cellular Responses to Speed Drug Discovery Built on standard CMOS technologies, the cellular sens- ing array chip uses a standard 35-mm cell culture dish with the bottom removed to host the cells and expose them to the sensing surface. (Source: Georgia Tech)