The MEMS technology has been widely applied to bio-sensing. The resonant frequency of micro-cantilevers shows positive correlation with mass changes by target adherence. The literature reveals the low-aspect-ratio cantilever is advantageous for bio-detection. This study investigates the cantilever of hollowed structure, which can improve both the production rate and pattern precision. Three chosen geometric shapes of cantilevers are rectangle, triangle, and half-ellipse. Due to the limit of pattern line-width of 3μm, and the smallest laser reflection diameter 20×20μm2, the dimensions of cantilever are designed with the aspect ratio of 0.5, 1, 2 and the aspect ratio of inner cut 0, 0.5, 1, 2 at the same surface area 5000μm2. The simulation results indicate the optimum cantilevers among three geometric shapes are those of aspect ratio 0.5 with inner cut of aspect ratio 2 in half-ellipse, which improve the fabrication performance and maintain high sensitivity. In the bio-sensing test, the highest resonant frequency shift is 3.6 kHz and the mass loading of Thiobacillus ferrooxidans is 2.4×10-9g associated with the optimum cantilever at the concentration of bacteria 106 cell/ml.

微機電製程技術已經廣泛地運用在生物感測方面，由生物體附著改變微懸臂樑質量，可以利用共振頻率的變化來檢測出相對應的目標數。低長寬比(尤以長度越短彈性係數越大)的懸臂樑在同質量變化下，有更明顯的頻率轉變。本論文所提出的中空式微懸臂樑結構，可以提昇在懸臂樑製程中的蝕刻效率，以及圖型定義的精確度。使用三種基礎幾何形狀的中空式懸臂樑：長方形、三角形及半橢圓形在雷射光點大小與圖型線寬的限制下，以感測表面積為5000μm2為準，分別由長寬比0.5、1、2，配合相似形狀中空結構長寬比0(無中空)、0.5、1、2予以分析。固定感測表面積尺寸，可以提供相同的生物附著檢測機率。高長寬比中空結構與低長寬比懸臂樑，對於製程時間及感測靈敏度助益最大。經由模擬分析，發現長寬比0.5半橢圓形懸臂樑及中空結構長寬比2，為最佳形狀設計。再透過實驗與模擬對照驗證下，此最佳的半橢圓形在Thiobacillus ferrooxidan 檢測濃度為106 cell/ml的專一性生物反應後，獲得平均頻率變化為3.6 kHz 及質量變化為2.4×10-9 公克。

[1] H. Hocheng, J.C. Wang, J.H. Chang, and W.C. Shen, “Laser-Guided Pattern Writing through Thiobacillus Ferrooxidans Metabolite”, Microelectronic Engineering, vol. 86, pp. 565-568, 2009.
[2] L.T. Mazzola and S.P. A. Fodor, “Imaging Biomolecule Arrays by Atomic Force Microscopy”, Affymetrix Biophysical Journal, vol. 68, pp. 1653-1660, 1995.
[3] U. Dammer, M. Hegner, D. Anselmettit, P. Wagner, M. Dreier, W. Huber, and H.J. Güntherodt,” Specific Antigen/Antibody Interactions Measured by Force Microscopy”, Biophysical Journal, vol. 70, pp. 2437-2441, 1996.
[4] T. Laurila, H. Cattaneo, T. Pöyhönen, V. Koskinen, J. Kauppinen, and R. Hernberg, “Cantilever-Based Photoacoustic Detection of Carbon Dioxide Using a Fiber-Amplified Diode Laser”, Applied Physics B, vol. 83, pp. 285-288, 2006.
[5] V. Koskinen, J. Fonsen, J. Kauppinen, and I. Kauppinen, “Extremely Sensitive Trace Gas Analysis with Modern Photoacoustic Spectroscopy”, Vibrational Spectroscopy, vol. 42, pp. 239-242, 2006.
[6] N. Abedinov, C. Popov, Zh. Yordanov, Tzv. Ivanov, T. Gotszalk, P. Grabiec, W. Kulisch, I. W. Rangelow, D. Filenko and Yu. Shirshov, “Chemical Recognition based on Micromachined Silicon Cantilever Array”, Journal of Vacuum Science Technology B, vol. 21, pp. 2931-2936, 2003.
[7] Rashid Bashir, “BioMEMS: State-of-the-art in Detection, Opportunities and Prospects”, Advanced Drug Delivery Reviews, vol. 56, pp. 1565- 1586, 2004.
[8] R. Raiteri, M. Grattarola, H.J. Butt, and P. Skládal, “Micromechanical Cantilever-based Biosensors”, Sensors and Actuators B, vol.79, pp. 115-126, 2001.
[9] E. Finot, A. Passian and T. Thundat, “Measurement of Mechanical Properties of Cantilever Shaped Materials”, Sensors, vol. 8, pp. 3497-3541, 2008.
[10] Gerald A Urban, “Micro- and Nanobiosensors - State of the Art and Trends”, Measurement Science and Technology, vol. 20, 012001, 2009.
[11] J.H. Lee, K.H. Yoon, K.S. Hwang, J. Park, S. Ahn, and T.S. Kima, “Label Free Novel Electrical Detection Using Micromachined PZT Monolithic Thin Film Cantilever for the Detection of C-reactive Protein”, Biosensors and Bioelectronics, vol. 20, pp. 269-275, 2004.
[12] A. Gupta, D. Akin, and R. Bashir, “Single Virus Particle Mass Detection Using Microresonators with Nanoscale Thickness”, Applied Physics Letters, vol. 84, pp. 1976-1978, 2004.
[13] Christiane Ziegler, “Cantilever-based Biosensors”, Analytical and Bioanalytical Chemistry, vol. 379, pp. 946-959, 2004.
[14] N. Nugaeva, K. Y. Gfeller, N. Backmann, H. P. Lang, M. Düggelin, and Martin Hegner, “Micromechanical Cantilever Array Sensors for Selective Fungal Immobilization and Fast Growth Detection”, Biosensors and Bioelectronics, vol. 21 , pp. 849-856, 2005.
[15] J.E. Sader, J.W. M. Chon, and P. Mulvaney, “Calibration of Rectangle Atomic Force Microscope Cantilevers”, American Institute of Physics, vol. 70, pp. 3967-3969, 1999.
[16] R.E. Fernandez, Ve. Hareesh, E. Bhattacharya, and A. Chadha, “Comparison of a Potentiometric and a Micromechanical Triglyceride Biosensor”, Biosensors and Bioelectronics, vol. 24, pp. 1276-1280, 2008.
[17] J.M. Neumelster and W.A. Ducker, “Later, Normal, And Longitudinal Spring Constants of Atomic Force Microscopy Cantilevers”, American Institute of Physics, vol. 65, pp. 2527-2531, 1994.
[18] C.A. Clifford and M.P. Seah, “The Determination of Atomic Force Microscope Cantilever Spring Constants via Dimensional Methods for Nanomechanical Analysis”, Nanotechnology, vol. 16, pp. 1666-1680, 2005.
[19] J.E. Sader, I. Larson, P. Mulvaney, and L.R. White, “Method for the Calibration of Atomic Force Microscope Cantilevers”, American Institute of Physics, vol. 66, pp. 3789-3798, 1995.
[20] C.T. Gibson, B.L. Weeks, J.R.I. Lee, C. Abell, and T. Rayment, “A Nondestructive Technique for Determining the Spring Constant of Atomic Force Microscope Cantilever”, American Institute of Physics, vol. 72, pp. 2340-2343, 2001.
[21] F.T. Goericke and W.P. King, “Modeling Piezoresistive Microcantilever Sensor Response to Surface Stress for Biochemical Sensors”, IEEE Sensors Journal, vol. 8, pp. 1404-1410, 2008.
[22] A. Loui, F.T. Goericke, T.V. Ratto, J. Lee, B.R. Hart, and W.P. King, “The Effect of Piezoresistive Microcantilever Geometry on Cantilever Sensitivity During Surface Stress Chemical Sensing”, Sensors and Actuators, vol. 147, pp. 516–521, 2008.
[23] J Bühlery, F-P Steiner and H Baltes, “Silicon Dioxide Sacrificial Layer Etching in Surface Micromachining”, Journal of Micromechanics and Microengineering, vol. 7, R1–R13, 1997.
[24] K.R. Williams and R.S. Muller, “Etch Rates for Micromachining Processing”, Journal of Microelectromechanical Systems, vol. 5, pp. 256-269, 1996.
[25] K.R. Williams, K. Gupta, and M. Wasilik, “Etch Rates for Micromachining Processing—Part II”, Journal Of Microelectromechanical Sysrems, vol. 12, pp. 761-778, 2003.
[26] G.T. A. Kovacs, N.I. Maluf, and K.E. Petersen, “Bluk Micromachining of Silicon”, Proceedings of the IEEE, vol. 86, pp. 1536-1551, 1998.

[27] B. Ilic, D. Czaplewski, H. G. Craighead, P. Neuzil, C. Campagnolo and C. Batt, “Mechanical Resonant Immunospecific Biological Detector”, Applied Physics Letters, vol. 77, pp. 450-452, 2000.
[28] Y. Huang, H. Liu, K. Li, Y. Chen, Q. Zhang, and X. Wu, “The Influence of Refractive Index Change on a Micro-Cantilever Bio/Chemical Sensor System based on Optical Lever Read-Out Method”, Sensors and Actuators A, vol. 148, pp. 329-334, 2008.
[29] K.A. Yoo, K.H. Na, S R. Joung, B.H. Nahm, C. J. Kang and Yong-Sang Kim, “Microcantilever-Based Biosensor for Detection of Various Biomolecules”, Japanese Journal of Applied Physics, vol. 45, pp. 515-518, 2006.
[30] G.A. Campbell, R. Mutharasan, “Detection and Quantification of Proteins using Self-excited PZT-glass Millimeter-sized Cantilever”, Biosensors and Bioelectronics, vol. 21, pp. 597-607, 2005.
[31] B.K. Oh, Y.K. Kim, W. Lee, Y.M. Bae, W.H. Lee, and J.W. Choi, “Immunosensor for Detection of Legionella Pneumophila using Surface Plasmon Resonance”, Biosensors and Bioelectronics, vol. 18, pp. 605-611, 2002.
[32] H. Hocheng, J.N. Hung, and Y.H. Guu, “Various Fatigue Testing of Polycrystalline Silicon Microcantilever Beam in Bending”, Japanese Journal of Applied Physics, vol. 47, pp. 5256-5261, 2008.
[33] F.G. Tseng, Lectures of Micro System Design (ESS5850), National Tsing Hua University, Lecture Chapter 2-2 - 3-2, 2008.
[34] W. Sand, K. Rohde, B. Sobotke, and C. Zenneck, “Evaluation of Leptospirillum ferrooxidans for Leaching”, Applied and Environmental Microbiology, vol. 58, pp. 85-92, 1992.
[35] H.L. Liu, C.W. Chiu, and Y.C. Cheng, “The Effects of Metabolites from the Indigenous Acidithiobacillus thiooxidans and Temperature on the Bioleaching of Cadmium from Soil”, Biotechnology and Bioengineering, vol. 83, pp. 638-645, 2003.
[36] S.G. Gupta and A.D. Agate, “Preservation of Thiobacillus ferroxidans and Thiobacillus thiooxidans with Activity Check”, Antonie van Leeuwenhoek, vol.52, pp. 121-127, 1986.
[37] N. Nugaeva, K.Y. Gfeller, N. Backmann, H.P. Lang, M. Düggelin, and M. Hegner, “Micromechanical Cantilever Array Sensors for Selective Fungal Immobilization and Fast Growth Detection”, Biosensors and Bioelectronics, vol. 21, pp. 849-856, 2005.
[38] S. Stolyarova, S. Cherian, R. Raiteri, J. Zeravik, P. Skladal, and Y. Nemirovsky, “Composite Porous Silicon-Crystalline Silicon Cantilevers for Enhanced Biosensing”, Sensors and Actuators B, vol. 131, pp. 509-515, 2007.
[39] Raj Mutharasan, “Cantilever Sensors for Pathogen Detection”, Principles of Bacterial Detection: Biosensors, Recognition Receptors and Microsystems, Chapter 18, Springer Science+Business Media, 2008.