Sains Malaysiana 40(1)(2011): 71–74

Fabrication Effects on Polysilicon-based Microcantilever Piezoresistivity for Biological Sensing Application

(Kesan Proses Fabrikasi Terhadap Piezorintangan Mikrokantilever Berasaskan Bahan Polisilikon untuk Aplikasi Penderiaan Biologi)

Nina Korlina Madzhi^1, *, Anuar Ahmad², Balkish Natra¹, Mastura Sidek¹ & Lee Yoot Khuan¹

¹Faculty of Electrical Engineering, Universiti Teknologi MARA

40450 Shah Alam, Selangor, Malaysia

²Faculty of Engineering, Universiti Industri Selangor

Jalan Zirkon A7/A, Seksyen 7, 40000 Shah Alam, Selangor, Malaysia

Received: 7 December 2009 / Accepted: 16 July 2010

ABSTRACT

In principle, adsorption of biological molecules on a functionalized surface of a microfabricated cantilever will cause a surface stress and consequently the cantilever bending. In this work, four different type of polysilicon-based piezoresistive microcantilever sensors were designed to increase the sensitivity of the microcantilevers sensor because the forces involved is very small. The design and optimization was performed by using finite element analysis to maximize the relative resistance changes of the piezoresistors as a function of the cantilever vertical displacements. The resistivity of the piezoresistivity microcantilevers was analyzed before and after dicing process. The maximum resistance changes were systematically investigated by varying the piezoresistor length. The results show that although the thickness of piezoresistor was the same at 0.5 μm the resistance value was varied.

Keywords: Biological sensing; piezoresistive; microcantilever; resistivity

ABSTRAK

Pada prinsipnya, jerapan molekul biologi pada permukaan yang fungsikan oleh kantilever yang telah difabrikasi akan menyebabkan tegangan permukaan dan akibatnya lenturan pada kantilever. Dalam kajian ini, empat jenis sensor piezorintangan mikrokantilever berasakan bahan polisilicon direka untuk meningkatkan sensitiviti sensor mikrokantilever memandangkan tekanan yang terlibat adalah sangat kecil. Reka bentuk dan pengoptimuman dilakukan dengan menggunakan analisis elemen hingga memaksimumkan perubahan pertahanan relatif daripada piezorintangan sebagai fungsi perpindahan menegak kantilever. Ukuran rintangan dari piezorintangan mikrokantilever dianalisis sebelum dan selepas proses ‘dicing’. Perubahan maksimum nilai rintangan diselidiki secara sistematik dengan mengubah ukuran panjang piezorintangan. Keputusan kajian menunjukkan bahawa walaupun ketebalan piezorintangan adalah sama iaitu sebanyak 0.5 μm tetapi nilai rintangan adalah berbeza.

Kata kunci: Mikrokantilever; penderiaan biologi; piezorintangan; rintangan

REFERENCES

Mohd Zahid Ansari, C.C. 2008. Design and Analysis of a high sensitive Microcantilever Biosensor for Biomedical Applications. Proceedings of International Conference on BioMedical Engineering and Informatics (BMEI'08) 593-597.

Nina Korlina Madzhi, Anuar Ahmad & Lee Yoot Khuan. 2008. Design and Fabrication of Polysilicon-based Piezoresistive Microcantilever for Biological Sensing. International Conference on Nanoscience and Nanotechnology 1136: 801-806.

Porter, T.L. & Eastman, M.P. 2001. Sensor based on piezoresistive microcantilever technology. Sensors and Actuators A: Physical 88(1): 47-51.

Sepaniak, M., P.D. & Nickolay Lavrik. 2004. Cantilever transducers as a platform for chemical and biological sensors, Review of Scientific Instruments 75(7): 2229-2253.

Tabard-Cossa, M.G. & L.Y. Beaulieu1, P. 2005. A differential microcantilever-based system for measuring surface stress changes induced by electrochemical reactions. Sensors and Actuators B 107: 233-241.

Vashist, S.K. 2007. A Review of Microcantilevers for Sensing Applications. Online Journal of Nanotechnology 3(June) DOI: 10.2240/azojono0115

Venkata Chivukula 2006. Simulation of SiO₂-based piezoresistive microcantilevers. Sensors and Actuators B 125(2): 526-533.

*Corresponding author; email: ninak654@salam.uitm.edu.my