摘要:
A FET gas sensor having a relatively low operating temperature, for example, room temperature, is free from cross sensitivities from interfering gases by a preceding in-line filter. The sensor's service life is substantially stabilizable by using fabric-like activated charcoal filters which can be regenerated by a moderate temperature increase, and by limiting the diffusion of the analyte gas, which is made possible by the relatively small amount of gas detectable on the sensitive layer of the sensor. This substantially increases the service life of the filters. The gas sensor eliminates cross sensitivities to thereby increase the detection reliability thereof. Also, the gas sensor has relative long term stability and is economical to build. The gas sensor can read relatively weak signals generated by gas-sensitive layers, for example, without other stronger gas signals interfering with the weak signals.
摘要:
A gas sensitive field effect transistor comprises a semiconductor substrate that includes a capacitance well, and source and drain regions of a field effect transistor. A gate of the field effect transistor is separated from the semiconductor substrate by an insulator, and a gas sensitive layer separated from the gate by an air gap. The field effect transistor provides an output signal indicative of the presence of a target gas within the air gap to an amplifier, which provides an amplified output signal that is electrically coupled to the capacitance well.
摘要:
A gas-sensitive field-effect transistor (GasFET) for the detection or measurement of an amount of hydrogen sulfide present in ambient air includes a raised gate electrode and a transistor structure. The raised gate electrode may be formed from or coated with a gas-sensitive material such as tin oxide, or silver, silver oxide or mixtures thereof. An insulator layer may be disposed on top of the transistor structure. An air gap is formed between the gas-sensitive layer of the raised gate electrode and the insulator layer on top of the transistor structure.
摘要:
The invention relates to an FET-based gas sensor comprising a gas channel for diffusing a measuring gas to a gas-sensitive layer which is actively connected to a FET for signal readout. According to the invention, an electrochemical element is at least partially inserted into the gas channel for the electrochemical conversion of interfering gases. The arrangement is permeable to the target gas.
摘要:
Method of effecting a readout of a gas-sensitive field-effect transistor having an air gap between a gate electrode with a gas-sensitive layer and the readout transistor, in which a potential occurring on the gas-sensitive layer in the presence of a target gas is passed through a noncontacting floating gate electrode to the transistor, wherein the potential of a reference electrode, which together with the floating gate electrode generates a capacitance Cw, is tracked to the potential of the floating gate electrode in order to eliminate the capacitance Cw during the measurement.
摘要翻译:在具有气体敏感层的栅电极和读出晶体管之间进行气体敏感场效应晶体管的读出的方法,其中在存在目标的情况下在气敏层上发生电位 气体通过非接触式浮栅电极到达晶体管,其中参考电极的电位与浮动栅电极一起产生电容C w i被追踪到浮置栅极的电位 电极,以便在测量期间消除电容C W>。
摘要:
A gas sensor based on a field effect transistor (“FET”) evaluates both a change in work function of a gas-sensitive layer of the FET and a change in the capacitance of the layer. Thus, two physically independent signals are read from the gas-sensitive layer, each signal representing a sensitivity to a different gas. This reduces the effect of cross-sensitivities; that is, of one gas on the target gas. The underlying physical mechanisms, the first causing a change in the work function in a reaction with gases and the second causing a change in the capacitance of the sensitive layer, are widely different. Because of this, the two parameters demonstrate different gas sensitivities. If the reactions to both gases are known, the effect of the interfering gas on the sensor signal can be compensated for, and with this the concentration of the target gas can be determined.
摘要:
A FET gas sensor having a relatively low operating temperature, for example, room temperature, is free from cross sensitivities from interfering gases by a preceding in-line filter. The sensor's service life is substantially stabilizable by using fabric-like activated charcoal filters which can be regenerated by a moderate temperature increase, and by limiting the diffusion of the analyte gas, which is made possible by the relatively small amount of gas detectable on the sensitive layer of the sensor. This substantially increases the service life of the filters. The gas sensor eliminates cross sensitivities to thereby increase the detection reliability thereof. Also, the gas sensor has relative long term stability and is economical to build. The gas sensor can read relatively weak signals generated by gas-sensitive layers, for example, without other stronger gas signals interfering with the weak signals.
摘要:
An operating method is disclosed for the selective detection of a target gas in a gas mixture to be measured by a field effect transistor with a gas-sensitive layer disposed on a carrier substrate, wherein the gas mixture to be measured is prepared by an electrochemical element such that the measured gas mixture includes minimal amounts of interfering gases that interfere with the measurement of the target gas, and/or at least one target gas is activated such that it is detected by the gas-sensitive layer.
摘要:
A gas-sensitive field-effect transistor may be formed from a substrate with a gas-sensitive layer and a transistor processed separately and then assembled. The substrate may be patterned to form spacers by which the height of an air gap between the transistor and the sensitive layer may be adjustable to a relatively precise degree. Formation of the spacers can be achieved by patterning the substrate using material-removal techniques. The height of the spacers may be adjusted in the layer thickness of the gas-sensitive layer and for the transistor fabricated using a CMOS process. Suitable techniques for producing recesses between the spacers include, for example, polishing, cutting, sandblasting, lithographic dry etching, or wet-chemical etching. Suitable materials for the substrate may include, for example, glass, ceramic, aluminum oxide, silicon, or a dimensionally stable polymer. Following preparation of the substrate and the transistor, the two elements of the transistor are joined, for example, using flip-chip methods or adhesive-bonding technology.
摘要:
A gas-sensitive field-effect transistor may be formed from a substrate with a gas-sensitive layer and a transistor processed separately and then assembled. The substrate may be patterned to form spacers by which the height of an air gap between the transistor and the sensitive layer may be adjustable to a relatively precise degree. Formation of the spacers can be achieved by patterning the substrate using material-removal techniques. The height of the spacers may be adjusted in the layer thickness of the gas-sensitive layer and for the transistor fabricated using a CMOS process. Suitable techniques for producing recesses between the spacers include, for example, polishing, cutting, sandblasting, lithographic dry etching, or wet-chemical etching. Suitable materials for the substrate may include, for example, glass, ceramic, aluminum oxide, silicon, or a dimensionally stable polymer. Following preparation of the substrate and the transistor, the two elements of the transistor are joined, for example, using flip-chip methods or adhesive-bonding technology.