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Antibody Immobilization in ZnO-Thin film transistors for low-cost biosensors applications
* 1 , 2 , 1 , 2
1  Centro de Investigación en Biotecnología Aplicada del Instituto Politécnico Nacional (CIBA-IPN)
2  Centro de Investigaciones en Dispositivos Semiconductores del Instituto de Ciencias de la Benemérita Universidad Autónoma de Puebla (BUAP)


The antibody immobilization with low-cost materials and label-free methods are a challenge for the fabrication of biosensor devices. In this work, it was developed a strategy for antibody immobilization on ZnO TFTs over polyethylene terephthalate (PET) as a recyclable plastic substrate. In a first approach we performed a detection of 1x108 enteropathogenic E. coli UFC/mL used as our testing model. Antibodies were biofunctionalized using a label-free strategy for bacterial detection. This strategy was able to couple the physics of transistors, the film deposition at low temperature and the binding of the biological recognition element (antibody) without affecting the functionality of the device. Fourier Infrared spectroscopy (FTIR) is a non-destructive technique used for monitoring the complete process, showing the characteristic signals (amide I, II and S-S) related to the antibody immobilization on ZnO-TFTs. Moreover, the transfer characteristics allowed us to observe the device before and after the immobilization and the changes in the shift of the threshold voltage Vt. The use of a recyclable plastic substrate PET enables the compatibility with flexible electronics that could contribute for a low-cost biosensor useful in rural communities that do not have the necessary infrastructure and trained personnel for pathogenic bacterial detection in food or water. The development of this technology has the versatility to be extrapolated to different testing models, allowing the early detection of emerging diseases (bacterial or viral), and also it provides the opportunity to end-users for self-testing.

Keywords: TFTs; biosensor; antibodies; ZnO
Comments on this paper
Andres Galdamez
Thank you for the contribution. It is a very interesting work. Have you explored the reusability of the sensor?
Rafael Antonio Salinas Domínguez
Currently different commercial biosensors (such as glucose test strips and pregnancy tests) are discarded after a single use. At this stage the study develops pilot tests in a real environment to make the development more complete and be compatible with international standards, however, once these conditions are established, the option of reuse could be explored (with the limitations of the biological recognition element ) or the perspective of a disposable biosensor with recyclable materials that covers the need for devices with low-cost and recyclable materials that can be disposed of in a safe and environmentally friendly way.