微流體系統是影響醫療和化學領域的新一代系統。對於一項基於流體的系統，
流速的測量方法對於系統的性能穩定與否至關重要。常見的解決方案是將微流體
系統（在本例中為玻璃微流控晶片）的流體通道入口或出口接上商用流量感測器。
然而，僅連接在晶片外部這項限制，可能會導致空間的佔用或流量測量不準確等
問題。因此，本研究旨在開發一種整合在晶片上的流量感測器，以達到節省空間
的目的，同時希望提高精度。另一個優點是本研究中的感測器可以在整個晶片中
調整感測器的位置，達到測量晶片上各處通道的流速，這項提升會改善使用複雜
設計，但無法改變感測位置這項缺點。本研究使用的感測器的原理是熱流量感測。
基於此原理，利用物理模擬軟體對感測器在晶片上進行開發與模擬，開發完成後，
進行微影製程、金屬蒸鍍製程、乾式及濕式蝕刻製程等微加工製程來製造晶片和
感測器。最後，進行電路實驗來測試晶片。至此可使用寬 20μm、長 3000μm 的
加熱器可進行最高 75℃的加熱，並測得 0~20μL/min 的流量。

Microfluidic system is a new-generation system impacting the medical and chemical field. For a fluid-based system, a method of flow velocity measurement is crucial for steady performance of the system. A common solution would be to introduce commercial flow rate sensors connected to the inlet or outlet of the fluid channel of the
microfluidic system. However, the restrictions to only attach outside the chip may cause problems like space occupation or inaccuracy off low flow measurement. Thus, this research is aiming to develop a flow rate sensor integrated on the chip itself to achieve space saving and hope to increase accuracy at the same time, while avoiding
contamination and undesired electro-chemical reaction caused by exposing the metal part to the fluid. Another advantage would be the freedom to place the sensor throughout the whole chip measuring any channel. The principle of the sensor in this research is colorimetric thermal flow sensing. Based on this principle, the chip is been
designed and simulated using multi-physics simulation software, fabricated and experimentally characterized. Optimal shapes and dimensions of the sensor were determined in the designing stage. Micro-fabrication processes such as photolithography, metal vaporation, wet and dry etching, are utilized to fabricate the
chip and the sensors. Finally, electrical circuit experiments are performed to test the chip. Up to now, 75°C of heating can be performed using a 20μm wide, 2000μm long heater. The flow as low as 0~10μL/min can be linearly measured.

[1] E. Tamaki, K. Sato, M. Tokeshi, K. Sato, M. Aihara, and T. Kitamori, "Singlecell analysis by a scanning thermal lens microscope with a microchip: direct
monitoring of cytochrome c distribution during apoptosis process," Analytical
chemistry, vol. 74, no. 7, pp. 1560-1564, 2002.
[2] J. Bryzek, "Impact of MEMS technology on society," Sensors and Actuators
A: Physical, vol. 56, no. 1-2, pp. 1-9, 1996.
[3] M. Tanaka, "An industrial and applied review of new MEMS devices
features," Microelectronic engineering, vol. 84, no. 5-8, pp. 1341-1344, 2007.
[4] J. W. Judy, "Microelectromechanical systems (MEMS): fabrication, design
and applications," Smart materials and Structures, vol. 10, no. 6, p. 1115,
2001.
[5] E. Verpoorte and N. F. De Rooij, "Microfluidics meets MEMS," Proceedings
of the IEEE, vol. 91, no. 6, pp. 930-953, 2003.
[6] H.-M. Jung, S.-B. Cho, and J.-H. Lee, "Design of smart piezoresistive pressure
sensor," in 5th Korea-Russia International Symposium on Science and
Technology. Proceedings. KORUS 2001 (Cat. No. 01EX478), 2001, vol. 1:
IEEE, pp. 202-205.
[7] J. T. Kuo, L. Yu, and E. Meng, "Micromachined thermal flow sensors—A
review," Micromachines, vol. 3, no. 3, pp. 550-573, 2012.
[8] M. Z. Mielli and M. N. Carreño, "Thermal flow sensor integrated to PDMSbased microfluidic systems," in 28th Symposium on Microelectronics
Technology and Devices (SBMicro 2013), 2013: IEEE, pp. 1-4.
[9] Y. Kikutani et al., "Application of flowing thermal lens to flow sensors for
53
microchemical chips," in The 13th International Conference on Solid-State
Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers.
TRANSDUCERS'05., 2005, vol. 1: IEEE, pp. 380-383.
[10] B. Y. Kim, L. Y. Hong, Y. M. Chung, D. P. Kim, and C. S. Lee, "Solvent‐
resistant PDMS microfluidic devices with hybrid inorganic/organic polymer
coatings," Advanced Functional Materials, vol. 19, no. 23, pp. 3796-3803,
2009.
[11] J. Stevenson and A. Gundlach, "The application of photolithography to the
fabrication of microcircuits," Journal of Physics E: Scientific Instruments, vol.
19, no. 9, p. 654, 1986.
[12] J. P. Hirth and G. M. Pound, "Evaporation of metal crystals," The Journal of
Chemical Physics, vol. 26, no. 5, pp. 1216-1224, 1957.
[13] L. Udachan, S. Shivaprasad, P. Ashrit, and M. Angadi, "Electrical resistivity
and temperature coefficient of resistance of vacuum evaporated thin chromium
films," physica status solidi (a), vol. 60, no. 2, pp. K191-K194, 1980.
[14] F. W. Chong and Y. H. Yew, "Wire bond scalable design methodology," in
2016 IEEE 18th Electronics Packaging Technology Conference (EPTC), 2016:
IEEE, pp. 93-96.
[15] J. L. Hudson and T. Tsotsis, "Electrochemical reaction dynamics: a review,"
Chemical Engineering Science, vol. 49, no. 10, pp. 1493-1572, 1994.
[16] H.-B. Kim, T. Hagino, N. Sasaki, N. Watanabe, and T. Kitamori,
"Spectroelectrochemical detection using thermal lens microscopy with a glasssubstrate microelectrode-microchannel chip," Journal of Electroanalytical
Chemistry, vol. 577, no. 1, pp. 47-53, 2005.
[17] F. Warkusz, "The size effect and the temperature coefficient of resistance in
54
thin films," Journal of Physics D: Applied Physics, vol. 11, no. 5, p. 689,
1978.
[18] V. V. Ryzhkov et al., "Integrated membrane-free thermal flow sensor for
silicon-on-glass microfluidics," Lab on a Chip, vol. 23, no. 12, pp. 2789-2797,
2023.
[19] Z. Malinowski, J. G. Lenard, and M. Davies, "A study of the heat-transfer
coefficient as a function of temperature and pressure," Journal of materials
processing technology, vol. 41, no. 2, pp. 125-142, 1994.
[20] W.-J. Hwang, K.-S. Shin, J.-H. Roh, D.-S. Lee, and S.-H. Choa, "Development
of micro-heaters with optimized temperature compensation design for gas
sensors," Sensors, vol. 11, no. 3, pp. 2580-2591, 2011.
[21] U. K. Sanivada, D. Esteves, L. M. Arruda, C. A. Silva, I. P. Moreira, and R.
Fangueiro, "Joule-heating effect of thin films with carbon-based
nanomaterials," Materials, vol. 15, no. 12, p. 4323, 2022.