Microarray Probe Development for the Imaging of Human Tumors

Abstract

Tissues of different composition or type can be distinguished due to differences in electrical impedance, measured using electrochemical impedance spectroscopy (EIS). Real-time EIS measurements presented as tissue images can potentially help surgeons identify the surgical margin of human tumors during organ resection. Sufficient surgical margin is important for patient survival rates but is presently estimated by non-quantitative methods such as visual inspection and physical palpation, and is verified for accuracy only post-surgery. Tumor images produced by existing impedance devices require the use of cumbersome stages and extensive supporting electronics to generate only coarse images of tumors in timespans of over 30 minutes. Consequently, existing impedance devices are impractical as real-time surgical tools for the verification of surgical margins. A rapid, non-translational electrode array probe is in development that will allow for the real-time imaging of human tumors, especially at the tumor/non-tumor interface. The newly developed measurement device has shown that physical probe translation can be eliminated through the use of a microarray as a probe and a multiplexing circuit as an electrode-switching mechanism. The custom designed probe and multiplexer enables successful imaging of tissue heterogeneity as demonstrated both in tissue phantoms and excised human liver tissue with metastatic colorectal cancer. Tissue images made from 26 serial EIS measurements can now be generated in just over two minutes. Additionally, the spatial resolution of the probe is now reaching almost 1 mm, not currently achieved by any other tissue electrical-characterization method in real-time. Therefore, the microarray probe can define a precise surgical margin in a time more acceptable for an active surgical environment.