重金屬離子對人體來說是有害物質，一旦不小心進入人體就難以排出體外，就算是肝臟也無法將其代謝，而經過長久的堆積對於人體的損害也是不容小覷，重金屬離子的累積主要透過飲用水、食物等經由飲食進入人體，然而現行的重金屬離子檢測方法主要都是透過實驗室大型機台花費至少一天的時間進行精密的測定，雖然有量測較為方便且快速的離子選擇性電極，但其卻無法偵測較低濃度的重金屬離子。而本研究致力於發展鎘離子的感測器，使其有攜帶方便、檢測時間短、能測到低濃度的重金屬離子同時又有不錯的靈敏度等特色，最重要的是操作方便，讓絕大多數的人都能輕易地操作。實驗中將離子選擇膜與場效電晶體的延伸閘極結合，加上感測電極的極小間距，使得鎘離子感測器有超越傳統能斯特元件的高靈敏度與低偵測極限。而台灣的飲用水鎘離子標準是不能大於0.01ppm，也就是8.89×10-8M[1]，而此研究中感測器的偵測極限可達到10-11M (0.001ppb)，與實驗室大型機台的偵測極限相差不到一個數量級，用來檢測飲用水中的鎘離子濃度是否符合法規濃度或是低濃度的檢測都相當適合。

Cadmium, one of the hazardous heavy metal, exists in our daily life. There is high risk that battery, pigment, and plastic contain cadmium. Besides, it is reported that the highest cadmium contained food are shellfish, liver, and kidney dishes. It is impossible to decompose or discharge most of the heavy metal as it gets into human body. Therefore, the amount of the heavy metal in human body would only increase. Cadmium in human body would cause lung cancer, osteomalacia and even proteinuria. Ingestion is the main way that cadmium ions get into human body. Thus, detection of cadmium in food and water before intake is very important. Though there are ways to detect cadmium, laboratory machines are the most used methods. By laboratory machine, we can detect low concentration of cadmium. However, the method is very time consuming and expensive. Electrochemical ion selective electrode is another way to detect cadmium. It has short response time and is easy to operate. Its low stability and poor detection limit are enormous disadvantages. In this research, we design an ion selective membrane field effect transistor(ISMFET). This ISMFET is featured with small size, high sensitivity, low detection limit, and easy to fabricate. This device can measure cadmium ion concentration in water. With short gap distant and high electric field, sensitivity of the device achieves 71 mV/log⁡M which is higher than ideal Nernst sensitivity. Besides, the dynamic range of the sensor is form 10-11 M (0.001ppb) to 10-7 M (11ppb). This wide range covering the highest cadmium ion concentration which is suggested by WHO in water. With this cadmium ISMFET, we can know the cadmium concentration in water in short time. Its simple design makes it easy to operate by anyone. Monitoring cadmium ions in water at home become possible with the development of this ISMFET.

[1] 行政院環境保護署. 飲用水水源水質標準. Available: https://wq.epa.gov.tw/Code/Business/Statutory.aspx?fbclid=IwAR06wtslJ1qQYXMvCeSDa1EML75W-swLDdddzY8Lq0P_1JBxGwTa-Fk_oGY
[2] Z. Rahman and V. P. Singh, "The relative impact of toxic heavy metals (THMs)(arsenic (As), cadmium (Cd), chromium (Cr)(VI), mercury (Hg), and lead (Pb)) on the total environment: an overview," Environmental monitoring and assessment, vol. 191, p. 419, 1.
[3] L. Järup, "Hazards of heavy metal contamination," British medical bulletin, vol. 68, pp. 167-182, 2.
[4] W. H. Organization, "Ten chemicals of major public health concern," World Health Organization, pp. 1-4, 56.
[5] J. Börjesson, T. Bellander, L. Järup, C. Elinder, and S. Mattsson, "In vivo analysis of cadmium in battery workers versus measurements of blood, urine, and workplace air," Occupational and environmental medicine, vol. 54, pp. 424-431, 3.
[6] L. Huang, L. Liu, T. Zhang, D. Zhao, H. Li, H. Sun, P. L. Kinney, M. Pitiranggon, S. Chillrud, and L. Q. Ma, "An interventional study of rice for reducing cadmium exposure in a Chinese industrial town," Environment international, vol. 122, pp. 301-309, 4.
[7] C. Chen, P. Xun, M. Nishijo, and K. He, "Cadmium exposure and risk of lung cancer: a meta-analysis of cohort and case–control studies among general and occupational populations," Journal of Exposure Science and Environmental Epidemiology, vol. 26, p. 437, 5.
[8] C. Grant, W. Buckley, L. Bailey, and F. Selles, "Cadmium accumulation in crops," Canadian Journal of Plant Science, vol. 78, pp. 1-17, 6.
[9] S. M. Pyle, J. M. Nocerino, S. N. Deming, J. A. Palasota, J. M. Palasota, E. L. Miller, D. C. Hillman, C. A. Kuharic, W. H. Cole, and P. M. Fitzpatrick, "Comparison of AAS, ICP-AES, PSA, and XRF in determining lead and cadmium in soil," Environmental science & technology, vol. 30, pp. 204-213, 7.
[10] J. Allibone, E. Fatemian, and P. J. Walker, "Determination of mercury in potable water by ICP-MS using gold as a stabilising agent," Journal of Analytical Atomic Spectrometry, vol. 14, pp. 235-239, 8.
[11] M. Morita, J. Yoshinaga, and J. S. Edmonds, "The determination of mercury species in environmental and biological samples (Technical report)," Pure and Applied chemistry, vol. 70, pp. 1585-1615, 9.
[12] M. Baret, D. Massart, P. Fabry, F. Conesa, C. Eichner, and C. Menardo, "Application of neural network calibrations to an halide ISE array," Talanta, vol. 51, pp. 863-877, 10.
[13] P. B. Ryan, N. Huet, and D. L. MacIntosh, "Longitudinal investigation of exposure to arsenic, cadmium, and lead in drinking water," Environmental health perspectives, vol. 108, pp. 731-735, 11.
[14] H. Roels, R. Lauwerys, J.-P. Buchet, A. Bernard, A. Vos, and M. Oversteyns, "Health significance of cadmium induced renal dysfunction: a five year follow up," Occupational and environmental medicine, vol. 46, pp. 755-764, 12.
[15] S. Satarug, M. R. Haswell-Elkins, and M. R. Moore, "Safe levels of cadmium intake to prevent renal toxicity in human subjects," British Journal of Nutrition, vol. 84, pp. 791-802, 13.
[16] M. Kasuya, H. Teranishi, K. Aoshima, T. Katoh, H. Horiguchi, Y. Morikawa, M. Nishijo, and K. Iwata, "Water pollution by cadmium and the onset of Itai-itai disease," Water Science and Technology, vol. 25, pp. 149-156, 14.
[17] M. Kasuya, "Recent epidemiological studies on itai-itai disease as a chronic cadmium poisoning in Japan," Water Science and Technology, vol. 42, pp. 147-154, 15.
[18] J. Godt, F. Scheidig, C. Grosse-Siestrup, V. Esche, P. Brandenburg, A. Reich, and D. A. Groneberg, "The toxicity of cadmium and resulting hazards for human health," Journal of occupational medicine and toxicology, vol. 1, p. 22, 16.
[19] A. T. Townsend, K. A. Miller, S. McLean, and S. Aldous, "The determination of copper, zinc, cadmium and lead in urine by high resolution ICP-MS," Journal of Analytical Atomic Spectrometry, vol. 13, pp. 1213-1219, 17.
[20] V. Vacchina, K. Połeć, and J. Szpunar, "Speciation of cadmium in plant tissues by size-exclusion chromatography with ICP-MS detection," Journal of Analytical Atomic Spectrometry, vol. 14, pp. 1557-1566, 18.
[21] EAG Laboratories. ICP-OES and ICP-MS Detection Limit Guidance. Available: https://www.eag.com/resources/appnotes/icp-oes-and-icp-ms-detection-limit-guidance/
[22] G. Tyler and S. Jobin Yvon, "ICP-OES, ICP-MS and AAS Techniques Compared," ICP Optical Emission Spectroscopy Technical Note, vol. 5, 19.
[23] 卢兵, 杜少文, 盛红宇, 武洋, 王耀武, and 卢安民, "AAS, ICP-AES, ICP-MS 及 XRF 测定地质样品中铜铅锌锰的对比研究," 黄金, vol. 35, pp. 78-81, 20.
[24] 陳敬岦 and 張國明, "以 NafionTM/高分子材料為結構的感測層應用在 pH-ISFET 離子選擇場效電晶體之研究," 21.
[25] M. Meyerhoff and W. Opdycke, "Ion-selective electrodes," in Advances in clinical chemistry. vol. 25, ed: Elsevier, 22, pp. 1-47.
[26] E. Bakker, P. Bühlmann, and E. Pretsch, "Carrier-based ion-selective electrodes and bulk optodes. 1. General characteristics," Chemical Reviews, vol. 97, pp. 3083-3132, 23.
[27] A. Shrivastava and P. Aggrawal, "Various Analytical Methodologies for Determination of Selective α1A Receptor Blocker Tamsulosin Hydrochloride and Its Combinations in Different Matrices," World Journal of Analytical Chemistry, vol. 1, pp. 37-48, 24.
[28] P. Bühlmann, E. Pretsch, and E. Bakker, "Carrier-based ion-selective electrodes and bulk optodes. 2. Ionophores for potentiometric and optical sensors," Chemical Reviews, vol. 98, pp. 1593-1688, 25.
[29] W. E. Morf, The principles of ion-selective electrodes and of membrane transport vol. 2: Elsevier, 26.
[30] 阎秉峰, "离子选择性电极的工作原理," 内蒙古科技与经济, vol. 3, pp. 106-109, 27.
[31] 阎秉峰, "离子选择性电极的工作原理," 内蒙古科技与经济, vol. 3, pp. 106-109, 28.
[32] C. M. McGraw, T. Radu, A. Radu, and D. Diamond, "Evaluation of Liquid‐and Solid‐Contact, Pb2+‐Selective Polymer‐Membrane Electrodes for Soil Analysis," Electroanalysis: An International Journal Devoted to Fundamental and Practical Aspects of Electroanalysis, vol. 20, pp. 340-346, 29.
[33] Y. Alifragis, A. Volosirakis, N. Chaniotakis, G. Konstantinidis, A. Adikimenakis, and A. Georgakilas, "Potassium selective chemically modified field effect transistors based on AlGaN/GaN two-dimensional electron gas heterostructures," Biosensors and Bioelectronics, vol. 22, pp. 2796-2801, 30.
[34] S. Plaza, Z. Szigeti, M. Geisler, E. Martinoia, B. Aeschlimann, D. Günther, and E. Pretsch, "Potentiometric sensor for the measurement of Cd2+ transport in yeast and plants," Analytical biochemistry, vol. 347, pp. 10-16, 31.
[35] Y. Alifragis, A. Volosirakis, N. Chaniotakis, G. Konstantinidis, E. Iliopoulos, and A. Georgakilas, "AlGaN/GaN high electron mobility transistor sensor sensitive to ammonium ions," physica status solidi (a), vol. 204, pp. 2059-2063, 32.
[36] C. Mihali and N. Vaum, "Use of plasticizers for electrochemical sensors," Recent Advances in Plasticizers, p. 125, 33.
[37] M.-H. Piao, J.-H. Yoon, G. Jeon, and Y.-B. Shim, "Characterization of all solid state hydrogen ion selective electrode based on PVC-SR hybrid membranes," Sensors, vol. 3, pp. 192-201, 34.
[38] J. K. Schneider, P. Hofstetter, E. Pretsch, D. Ammann, and W. Simon, "N, N, N′, N′‐Tetrabutyl‐3, 6‐dioxaoctan‐dithioamid, Ionophor mit Selektivität für Cd2+," Helvetica Chimica Acta, vol. 63, pp. 217-224, 35.
[39] H. Sauter and M. Dobler, "N, N, N′, N′‐Tetrabutyl‐3, 6‐dioxaoctan‐dithioamid, ein ionophor mit Cd2+‐Selektivität, Röntgenstrukturanalyse des Cd2+‐Komplexes," Helvetica Chimica Acta, vol. 65, pp. 1297-1303, 36.
[40] P. Bergveld, "Development, operation, and application of the ion-sensitive field-effect transistor as a tool for electrophysiology," IEEE Transactions on Biomedical Engineering, pp. 342-351, 37.
[41] J. Go and M. Alam, "Effect of fluid gate on the electrostatics of ISFET-based pH sensors," in 2010 18th Biennial University/Government/Industry Micro/Nano Symposium, 38, pp. 1-3.
[42] P. Li, B. Liu, D. Zhang, Y. e. Sun, and J. Liu, "Graphene field-effect transistors with tunable sensitivity for high performance Hg (II) sensing," Applied Physics Letters, vol. 109, p. 153101, 39.
[43] E. J. Guidelli, E. M. Guerra, and M. Mulato, "V2O5/WO3 mixed oxide films as pH-EGFET sensor: sequential re-usage and fabrication volume analysis," ECS Journal of Solid State Science and Technology, vol. 1, pp. N39-N44, 40.
[44] Y.-C. Huang, F.-S. Tsai, and S.-J. Wang, "Preparation of TiO2 nanowire arrays through hydrothermal growth method and their pH sensing characteristics," Japanese Journal of Applied Physics, vol. 53, p. 06JG02, 41.
[45] M. Spijkman, E. Smits, J. Cillessen, F. Biscarini, P. Blom, and D. De Leeuw, "Beyond the Nernst-limit with dual-gate ZnO ion-sensitive field-effect transistors," Applied Physics Letters, vol. 98, p. 043502, 42.
[46] C.-C. Liu, D. Bocchicchio, P. A. Overmyer, and M. R. Neuman, "A palladium-palladium oxide miniature pH electrode," Science, vol. 207, pp. 188-189, 43.
[47] P.-C. Yao, J.-L. Chiang, and M.-C. Lee, "Application of sol–gel TiO2 film for an extended-gate H+ ion-sensitive field-effect transistor," Solid State Sciences, vol. 28, pp. 47-54, 44.
[48] C.-H. Hsieh, I.-Y. Huang, and C.-Y. Wu, "A low-hysteresis and high-sensitivity extended gate FET-based chloride ion-selective sensor," in SENSORS, 2010 IEEE, 45, pp. 358-361.
[49] C.-S. Lee, S. Kim, and M. Kim, "Ion-sensitive field-effect transistor for biological sensing," Sensors, vol. 9, pp. 7111-7131, 46.
[50] H. Hirata and K. Higashiyama, "Analytical study of the lead ion-selective ceramic membrane electrode," Bulletin of the chemical society of Japan, vol. 44, pp. 2420-2423, 47.
[51] S.-i. Wakida, N. Sato, and K. Saito, "Copper (II)-selective electrodes based on a novel charged carrier and preliminary application of field-effect transistor type checker," Sensors and Actuators B: Chemical, vol. 130, pp. 187-192, 48.
[52] M. Asadnia, M. Myers, N. D. Akhavan, K. O'Donnell, G. A. Umana-Membreno, U. Mishra, B. Nener, M. Baker, and G. Parish, "Mercury (II) selective sensors based on AlGaN/GaN transistors," Analytica chimica acta, vol. 943, pp. 1-7, 49.
[53] Y.-T. Chen, I. Sarangadharan, R. Sukesan, C.-Y. Hseih, G.-Y. Lee, J.-I. Chyi, and Y.-L. Wang, "High-field modulated ion-selective field-effect-transistor (FET) sensors with sensitivity higher than the ideal Nernst sensitivity," Scientific reports, vol. 8, p. 8300, 50.