Extended Solution Gate OFET‐Based Biosensor for Label‐Free Glial Fibrillary Acidic Protein Detection with Polyethylene Glycol‐Containing Bioreceptor Layer

Abstract

A novel organic field effect transistor (OFET) -based biosensor is described for label-free glial fibrillary acidic protein (GFAP) detection. We report the first use of an extended solution gate structure where the sensing area and the organic semiconductor are separated, and a reference electrode is not needed. Different molecular weight polyethylene glycols (PEGs) are mixed into the bio-receptor layer to help extend the Debye screening length. The drain current change was significantly increased with the help of higher molecular weight PEGs, as they are known to reduce the dielectric constant. We also investigated the sensing performance under different gate voltage (Vg). The sensitivity increased after we decreased Vg from -5 V to -2 V, because the lower Vg is much closer to the OFET threshold voltage and the influence of attached negatively charged proteins become more apparent. Finally, the selectivity experiments toward different interferents were performed. The stability and selectivity are promising for clinical applications.

Influence of Bioreceptor Layer Structure on Myelin Basic Protein Detection using Organic Field Effect Transistor‐Based Biosensors

“…The chamber pressure during deposition was <6 × 10 −6 Torr. Next, gold electrodes (50 nm) and tetratetracontane (CH 3 (CH 2 ) 42 CH 3 , denote as C 44 ) protection layers were thermally evaporated through an interdigitated shadow mask, the structure of which was shown in our previous paper . The rates of all depositions were 0.4 Å s −1 and the channel width/length ratio was 28 ( W = 7 mm, L = 0.25 mm).…”

“…OFET‐based biosensors are being widely studied for potentially fast clinical diagnostics, with the advantages of flexibility, sensitivity, and low cost . Particularly, OFET‐based biosensors for protein sensing have progressed remarkably for label‐free analyte detection based on the specific immune binding property innate to particular antibodies . By the adjustment of device structures, various challenges have been successfully overcome.…”

“…The diblock copolymer polystyrene‐ co ‐acrylic acid (PS‐PAA) was used in the receptor layer. Song et al described an OFET‐based extended solution gate structure biosensor made by spin coating polystyrene‐ co ‐methacrylic acid (PS‐MA) as a receptor layer . These materials both have hydrophobic properties and high carboxyl group number densities, which are desirable for receptor layers.…”

Recent Advances in Immobilization Strategies for Biomolecules in Sensors Using Organic Field-Effect Transistors

“…A biometric layer that is as thick as several tens of nanometers is far beyond the Debye screening length, which makes detection difficult. Therefore, biometric identification must overcome the Debye length effect [49,50] or establish smaller identification units.…”

Integration of Biomaterials into Sensors Based on Organic Thin‐Film Transistors

“…Incorporating these biomaterials into sensors will endow the devices with excellent sensitivity, high selectivity, low detection limit, ease instrumentation as well as cost‐effective fabrication for label‐free biodetection. Synthetic biopolymers including polylactide (PLA), polydimethylsiloxane (PDMS), polyethylene glycol (PEG), and polyvinyl alcohol (PVA) were also integrated into OFETs for physical, chemical, and biological sensing . In addition, the rigid silicon substrates can be further substituted by flexible plastic or paper substrates, enabling a totally “green” electronics with high biocompatibility and biodegradability …”