▎ 摘　　要

NOVELTY - Biosensor comprises a field effect transistor (FET) comprising a source electrode, a drain electrode, where the source and drain electrodes are separated from each other by an electrode separation distance, a channel layer between the source electrode and the drain electrode, where the channel layer has a crumpled geometry, a sample reservoir in fluidic contact with the channel layer, where the sample reservoir is configured to hold a sample solution, and a gate electrode configured to electrically contact the sample solution in the sample reservoir, and the crumpled geometry of the channel increases a detection limit of the biosensor to molecules in an ionic solution. USE - The biosensor is useful for detecting a biomolecule such as DNA, RNA including miRNA, protein, or a small molecule circulating in plasma or whole blood, detecting amplification of a target polynucleotide. The system is useful for detecting a target polynucleotide in a sample solution (all claimed). ADVANTAGE - The biosensor has increased sensitivity, and detects a biomolecule in a robust, reliable and cost-effective, and avoids need for labels and associated optical components. The method is performed without labels and/or without surface-functionalization. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) method for detecting a biomolecule involves (a) providing the above-mentioned biosensor, (b) introducing the sample solution to the channel layer, (c) applying a gate voltage to the sample solution, and (d) monitoring a FET electrical parameter, where a change in the FET electrical parameter corresponds to presence of the biomolecule in the sample solution; (2) method for detecting amplification of a target polynucleotide involves (a) providing a field effect transistor (FET) having a crumpled semiconductor material channel that is configured to form a p-p interaction with single stranded DNA, (b) performing an amplification reaction in an amplification solution comprising single stranded DNA (ssDNA) primers to obtain an amplified solution, (c) contacting the FET with the amplified solution, and (d) electrically detecting with the FET an amount of ssDNA primer in the amplified solution; and (3) system comprising FET having a source electrode, a drain electrode, a channel layer between the source electrode and the drain electrode, a channel layer receiving surface that forms part of a sample reservoir, where the sample reservoir is configured to hold an amplifiable sample solution, an electrical detector electrically connected to the FET, amplifiable sample solution comprising ssDNA primers and amplification reagents to amplify the target polynucleotide, where during use the amplifiable sample solution contacts the channel layer receiving surface of the sample reservoir, ssDNA primers during use bind to the channel layer receiving surface by a noncovalent p-p interaction between the crumpled semiconductor material and an aromatic ring of the ssDNA at a higher affinity than dsDNA, and the electrical detector is configured to detect a level of ssDNA primer by detection of a change in a FET electrical parameter.