An IC-compatible polyimide pressure sensor with capacitive readout

A capacitive differential pressure sensor has been developed. The process used for the fabrication of the sensor is IC-compatible, meaning that the device potentially can be integrated on one chip with a suitable signal-conditioning circuit. A sensor for a differential pressure of ±1 bar has been fabricated and tested with a frequency-modulated detection circuit, and good agreement is found with the theoretical model of the sensor. A nominal sensitivity ¿C/C of 17% has been measured for a positive differential pressure of 1 bar. The resolution of the complete detection system is 2.5 mbar (250 Pa)

Computer assisted design study of a low-cost pressure sensor

The application of numerical techniques for the design of a low cost pressure sensor is described. The numerical techniques assist in addressing issues related to the thermo-mechanical performance of the sensor. This comprises the selection of the materials and dimensions used for the sensor itself and the substrate on which it is mounted. Moreover, simulations are applied to aid in the selection of suitable solder interconnect materials and dimensions. Where possible, the accuracy of the numerical predictions is assessed by comparing them to experiments on physical prototypes. The application of numerical simulations allowed for a reduction in the number of physical tests and thereby a reduction in design time and costs

A capacitive differential pressure sensor with polyimide diaphragm

A capacitive differential pressure sensor has been developed. The process used for the fabrication of the sensor is IC-compatible, meaning that the device can potentially be monolithically integrated on one chip with a suitable signal conditioning circuit. A sensor for a differential pressure range of ±1bar was fabricated and tested with a frequency modulated detection circuit, and good agreement was found with the theoretical model of the sensor. A nominal sensitivity ΔC/C of 18% has been measured for a positive differential pressure of 1 bar

Gas-Dependent Field Effect Transistor with an Electrodeposited Conducting Polymer Gate Contact

Field effect transistor structures with a conducting polymer gate contact have been realized. An electrodeposition technique, suitable for a wide range of conducting polymers, was used. This is illustrated with the deposition of two different types of polypyrroles. The sensors show responses to organic vapors due to partial charge transfer between the sorbed vapor and the conducting polymer, and can be used for electronic nose applications. Due to the measuring principle, based on work function instead of resistance changes, this sensor is also believed to be useful for fundamental research on gas-polymer interactions. ©1999 The Electrochemical Societ

The influence of a metal stent on the distribution of thermal energy during irreversible electroporation

Purpose: Irreversible electroporation (IRE) uses short duration, high-voltage electrical pulses to induce cell death via nanoscale defects resulting from altered transmembrane potential. The technique is gaining interest for ablations in unresectable pancreatic and hepatobiliary cancer. Metal stents are often used for palliative biliary drainage in these patients, but are currently seen as an absolute contraindication for IRE due to the perceived risk of direct heating of the metal and its surroundings. This study investigates the thermal and tissue viability changes due to a metal stent during IRE. Methods: IRE was performed in a homogeneous tissue model (polyacrylamide gel), without and with a metal stent placed perpendicular and parallel to the electrodes, delivering 90 and 270 pulses (15-35 A, 90 μsec, 1.5 cm active tip exposure, 1.5 cm interelectrode distance, 1000-1500 V/cm, 90 pulses/min), and in-vivo in a porcine liver (4 ablations). Temperature changes were measured with an infrared thermal camera and with fiber-optic probes. Tissue viability after in-vivo IRE was investigated macroscopically using 5-triphenyltetrazolium chloride (TTC) vitality staining. Results: In the gel, direct stent-heating was not observed. Contrarily, the presence of a stent between the electrodes caused a higher increase in median temperature near the electrodes (23.2 vs 13.3°C [90 pulses]; p = 0.021, and 33.1 vs 24.8°C [270 pulses]; p = 0.242). In-vivo, no temperature difference was observed for ablations with and without a stent. Tissue examination showed white coagulation 1mm around the electrodes only. A rim of vital tissue remained around the stent, whereas ablation without stent resulted in complete tissue avitality. Conclusion: IRE in the vicinity of a metal stent does not cause notable direct heating of the metal, but results in higher temperatures around the electrodes and remnant viable tissue. Future studies should determine for which clinical indications IRE in the presence of metal stents is safe and effective