Chemically-sensitive field effect transistors, systems, and methods for manufacturing and using the same

#The present disclosure generally relates to field effect transistors and methods of making and using the same for the analysis of biological or chemical materials or reactions and bioinformatics processing. More specifically, the present disclosure relates to two-dimensional nanomaterial-based field effect transistors useful for chemical and biological analysis.

#Certain types of transistor-based sensors have been described as useful for sensing applications. However, various existing designs have limited sensitivity and scalability.

#An apparatus includes a biosensor integrated circuit (IC) chip having one or more sensing zones within one or more well structures configured to receive a liquid comprising one or more biological analytes. The chip includes a passivation layer with an opening over a channel layer and including an array of graphene field effect transistors (gFETs). The individual gFETs include a graphene channel formed in the channel layer and form in a two-dimensional layer of carbon atoms, the graphene channel disposed on a dielectric oxide layer. A conductive drain is connected at a first end of the graphene channel and a conductive is source connected at a second end of the graphene channel. A liquid gate is formed above the top surface of the graphene channel upon receipt of the liquid. The biosensor IC chip further includes one or more reference electrodes formed in a metal layer of the biosensor IC chip and configured to contact the liquid, the one or more reference electrodes disposed at a horizontal distance apart from the graphene channels of the gFETs in the array, where at least one of the one or more reference electrodes is configured to apply a liquid gate voltage to the liquid and at least one of the one or more reference electrodes is configured to measure a liquid gate voltage of the liquid. The individual gFETs and the first and second reference electrodes are operable to enable a set of measurements to be made to sense one or more parameters of a biological analyte in the liquid based on changes in a shape of a chemical sensing Id-Vgs curve relative to a reference Id-Vgs, in response to the presence of the biological analyte in the liquid on or over the channels of the individual gFETs.

#In order that the advantages of the disclosure will be readily understood, a more particular description of the examples briefly described above will be rendered by reference to specific examples that are illustrated in the appended drawings. Understanding that these drawings depict only typical examples of the subject matter and are not therefore to be considered to be limiting of its scope, the subject matter will be described and explained with additional specificity and detail through the use of the accompanying drawings.

#FIG. 1A is a side sectional illustration of an ISFET device fabricated using traditional semiconductor FET transistor technology for the sensor transistor.

#FIG. 1B is a side sectional illustration of a substrate for use in a ChemFET, such as for a system for analysis of biological and/or chemical materials. In this instance, the substrate includes a dielectric layer having a source and a drain, and further includes a sensing zone having a graphene nanomaterial layer associated therewith.

#Reference throughout this specification to “one example,” “an example,” or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example. Thus, appearances of the phrases “in one example,” “in an example,” and similar language throughout this specification may, but do not necessarily, all refer to the same example, but mean “one or more but not all examples” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.

#Furthermore, the described features, structures, or characteristics of the disclosure may be combined in any suitable manner in one or more examples. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of examples of the subject matter. One skilled in the relevant art will recognize, however, that the claims may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

#The schematic flow chart diagrams included herein are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of one example of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Although various arrow types and line types may be employed in the flow chart diagrams, they are understood not to limit the scope of the corresponding method. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the method. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.