After 2022, when the Moore’s law rigorously fulfilled for CMOS technology, the future electronic devices entered into the co-integration period. The Silicon CMOS parts keep the circuit complexity at a low enough price, while the integrated layers can be enzyme membranes to offer sensitive transistors to low analyte concentrations, Organic Thin Film Transistors to put in agreement the Si-circuitry with commended OLEDs for displays, or biomaterials and nano-structured oxides to co-integrate biosensors at low prices and multiple usage for Lab-On-Chip applications. Proposals are multiple, alternative bio-devices are known as work-function, while nanoscale technologies open new facilities to co-immobilize enzymes and antibodies in the CMOS proximity. This work presents solution of co-integration between an enzyme receptor and Silicon MOS device. The final biosensor that works with field effect transistors (FET) as transducers and enzyme as bio-receptor is called EN-FET device. In the actual work, a traditional MOS-FET transistor is co-integrated with the glucose-oxidase enzyme, offering a glucose biosensor. The paper is focused on the manufacturing process optimization of an ENFET. Above the MOS gate oxide, the glucose-oxidase (GOX) receptor is entrapped onto a nano-structured-TiO2 compound, as a green technological solution, instead of Polycyclic aromatic hydrocarbons PAH functionalization techniques. The paper proposes multiple details for co-integration between MOS devices with enzymatic biosensors. The Ti conversion into nanostructured layer occurs by anodization. Separate situations of GOX entrapment on nanostructured TiO2 in contact to a Si-wafer are presented. Two cross-linkers are experimental studied for a better enzyme immobilization. The final part of the report combines experimental data with analytical models to extract the calibration curve of the ENFET transistor, prescribing in the same time a design methodology.
Audience take away:
- How TiO2 layers can be attached to Si-wafers.
- How glucose-oxidase enzyme is attached onto nanostructured TiO2 layer.
- Technological process characterizations are presented.