With fast recovery time and effective in situ tumor tissue killing ability, thermal ablation has become a popular treatment for tumors compared with chemotherapy and radiation. The thermal dose measurement of current technology is usually accompanied by monitoring a large area impedance across two ablation catheters and the localized impedance measurement is difficult to achieve.In this work, thermal-resistive sensor and impedance sensor are fabricated on the curved surface of a capillary tube with 1 mm outer diameter. The device is applied for real-time in situ tissue impedance monitoring during thermal ablation. The calibrated thermal-resistive sensors have an average temperature coefficient of resistance (TCR) of 0.00161 ± 5.9% • C -1 with an accuracy of ±0.7 • C. By adding electro-polymerized PEDOT:PSS (poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate)) on the 300 µm diameter gold electrodes, the interface impedance reduces two orders from 408 to 3.7 kΩ at 100 Hz. The Randles equivalent circuit model fittings show a two-order improvement in the electrode capacitance from 7.29 to 753 nF. In the ex vivo porcine liver laser ablation test, the temperature of the porcine liver tissue can reach 70 • C and the impedance would drop by 50% in less than 5 minutes. The integration of laser ablation fiber with the impedance and temperature sensors can further expand the laser ablation technique to smaller scale and for precise therapeutics.
Solution-processed organic semiconductors (OSCs) promote the development of the next generation of large-area, low-cost flexible electronics. To date, the properties of the flexible substrates such as chemical compatibility, roughness, and surface energy are still big challenges for the solution process, especially for high-performance ultrathin monolayer OSCs. Herein, van der Waals assembled organic field-effect transistors (OFETs) with layerby-layer lamination processes are reported. The active layer is an ultrathin single molecular layer 2,9-Didecyldinaphtho[2,3-b:2′,3′-f ]thieno[3,2-b] thiophene (C 10 -DNTT) which maintains decent electrical fidelity with mobility of 10.4 cm 2 V -1 s -1 after transfer. With the active layer transfer technique, the bias stability of OFETs can be significantly improved by tuning diverse hydrophobic self-assembly monolayers (SAMs) onto the dielectric which is a challenging task before the solution processing organic monolayer. A small subthreshold swing (SS) of 63 mV decade −1 is achieved by low surface energy phosphonic acid SAMs on high-κ AlO x dielectric. We further demonstrate a high-gain organic inverter amplifier that can be powered up by a coin cell on the 1.5 µm conformal parylene substrate and apply it for high-resolution electrocardiograph (ECG) sensing. The ECG sensors can provide a signal-tonoise ratio as high as 34 dB. It is believed that our device demonstrates the prospect of continuous monitoring for human health management.
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