Technology Advantages

There are a broad range of gas sensing technologies currently in use. Mass spectroscopy and gas chromatography systems are among the most sensitive and selective to detect particular gases, but existing systems are too large, heavy, and expensive for many applications. These systems require appropriate training to operate, and even the so called "portable" units are the size of a small suite case.


There are other technologies that are currently available that can be use to produce more portable products. Such technologies generally depend on the sensing gas to modify electrical characteristics of materials, the most popular of which is metal oxide semiconductors. While metal oxide semiconductor technology is smaller and can operate with reduced power compared to mass spectroscopy and gas chromatography, they still do not lend themselves to integration to standard silicon fabrication. This integration issue results from their relatively high temperature of operation of about 300°C, which i nterferes with the operation of the standard Si-based circuitry. Portable units utilizing these technologies are generally the size of a walky-talky. Furthermore, the power at which they operate (300mW to 800mW) is still much higher than is desirable for many portable applications. These factors limit the ability of this technology to serve the portable sensor market.


SensorBit’s technology addresses these concerns in that the sensors operate at room temperature, they can be integrated into CMOS fabrication processes, and the power requirement is expected to be lower by one to two orders of magnitude than metal oxide semiconductor sensors. These factors enable the SensorBit sensor to be made small enough to be integrated into small portable and power sensitive devices such as cell phones or wearable buttons. The sensitivity and selectivity of SensorBit’s technology is also expected to be much improved over metal oxide semiconductors due to the higher orthogonality and additional information offered by these sensors. It should be noted, however, that gas chromatography and spectroscopy will still be more sensitive and selective that what can be achieved with SensorBit’s sensing technology in identifying specific gas species. Therefore, SensorBit’s technology is not expected to displace such sensor systems.


Though not yet found widely in commercial markets, polymer-based sensor technologies are among the most promising for an entry into a high-volume low-cost sensor market. They are attractive because they are small, low power, have no moving parts, and are sensitive to various chemicals. SensorBit’s technology addresses the limitations of existing polymer-based technologies, among which are baseline shift due to undesirable moisture absorption, broad response to many analytes requiring substantial signal analysis of analyte identification, and deposition methods incompatible with silicon fabrication processes. The SensorBit polymer technology addresses these shortcomings. The key advantages of this technology over competitive sensor technologies can be summarized as follows:


Manufacturability: The sensor cell can be integrated directly into standard CMOS silicon, and the sensing polymers are solution based allowing low cost, high volume deposition methods.


Increased signal information from each sensor cell: Electrical Signal from the cell convey information about the analyte charge (through silicon current), size (through polymer current), and activation energy (comparison between signals at two different temperatures). This increased information results in better analyte selectivity and reduces the need for signal analysis.


Control over analyte/receptor interaction: The cell structure allows the charge of the polymer to be controlled by an electric field, attracting or repelling the analyte from the sensor measurement surface.


Increased immunity from sensor drift: The measured sensor cell is compared to the same cell at a higher temperature, giving rise to a continuously updated baseline signal, increasing immunity to sensor drift.


Moisture Tolerant: One of two identical columns of sensor cells is heated while the other column is being measured, and the two columns are swapped with sufficient frequency so that moisture build-up in either column of cells becomes a problem.


Receptor Diversity: In addition to organic semiconductor polymers doped with a receptor, the cell structure can accommodate a wide variety of different polymer-based sensing materials.


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