RapidET: a MEMS-based platform for label-free and rapid demarcation of tumors from normal breast biopsy tissues

The rapid and label-free diagnosis of malignancies in ex vivo breast biopsy tissues has significant utility in pathology laboratories and operating rooms. We report a MEMS-based platform integrated with microchips that performs phenotyping of breast biopsy tissues using electrothermal sensing. The microchip, fabricated on a silicon substrate, incorporates a platinum microheater, interdigitated electrodes (IDEs), and resistance temperature detectors (RTDs) as on-chip sensing elements. The microchips are integrated onto the platform using a slide-fit contact enabling quick replacement for biological measurements. The bulk resistivity (ρb), surface resistivity (ρs), and thermal conductivity (κ) of deparaffinized and formalin-fixed paired tumor and adjacent normal breast biopsy samples from N = 8 patients were measured. For formalin-fixed samples, the mean ρb for tumors showed a statistically significant fold change of 4.42 (P=0.014) when the tissue was heated from 25 °C to 37 °C compared to the adjacent normal tissue, which showed a fold change of 3.47. The mean ρs measurements also showed a similar trend. The mean κ of the formalin-fixed tumor tissues was 0.309 ± 0.02 W m^-1 K^-1 compared to a significantly higher κ of 0.563 ± 0.028 W m^-1 K^-1 for the adjacent normal tissues. A similar trend was observed in ρb, ρs, and κ for the deparaffinized tissue samples. An analysis of a combination of ρb, ρs, and κ using Fisher's combined probability test and linear regression suggests the advantage of using all three parameters simultaneously for distinguishing tumors from adjacent normal tissues with higher statistical significance.