Flexible Ultrathin Temperature Sensor Array as a Patch for Early Breast Cancer Detection

Early detection for breast cancer is crucial for improving survival rates. This paper presents the development of a flexible temperature sensor array designed for non-invasive breast cancer detection. The system leverages temperature mapping to identify thermal changes associated with malignancies in the breast. The array includes single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (SWCNT/PEDOT:PSS)-based temperature sensors. The array is fabricated on a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \mu ~\mathrm{m}$</tex>-thick polyimide substrate and encapsulated with a 500 nm-thick polydimethylsiloxane (PDMS) layer. The array conforms well to any surface due to its thinness and has a high temperature sensitivity (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-0.71 \%^{\circ} \mathrm{C}^{-1}$</tex>), rapid response (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.5 \pm 0.1$</tex> s), and recovery times (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4.1 \pm 0.3 ~\mathrm{s}$</tex>) across a linear detection range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$20-45^{\circ} \mathrm{C}$</tex>. Experimental validation using a silicone-based breast phantom demonstrates the array's ability to detect temperature differences and map distributions across varying silicone thicknesses, simulating shallow and deep tumors. This work aims to contribute to advancing wearable sensor technology for early-stage breast cancer detection.