N.V. Masalsky1

1 Federal State Institution «Scientific Research Institute for System Analysis of the Russian Academy of Sciences» (Moscow, Russia)
1 Masal1960@yandex.ru

A method for increasing the pH sensitivity of a sensor above the Nernst limit based on a complementary pair of silicon ribbon field ion-sensitive nanotransistors is discussed. In this work, three stages are combined - TCAD modeling, crystal fabrication and testing. Thus, we excluded the search for optimal technological parameters of silicon ribbon posts and additional research to optimize the manufacturing process. We also reduced the setup time of the software and measurement complex and obtained an assessment of the systematic measurement error. The volt-ampere characteristics of complementary transistors are optimized using 3D modeling performed using the TCAD Sentaurus instrument-technology modeling system using Sentaurus Devicee.2010.12. The numerical optimization strategy is to determine the size ranges of the ribbon sensitive region of an ion-sensitive transistor, where its current sensitivity is constant with the largest number of samples, implying that one sample is equivalent to one pH level. For further research, a prototype was taken with the dimensions of a sensitive area with a length of 1452 nm, a width of 184 nm and a height of ts = 38.5 nm, which has the maximum sensitivity of single transistors in the range of 14 samples. An experimental approbation has been carried out confirming the practical applicability of the method of pH-metry of liquid solutions based on a complementary scheme of ion-sensitive nanotransistors. The experimental sample developed using TCAD modeling revealed sensitivity above the Nernst limit by about 25% in the pH range from 3 to 12 with a sensitivity of 0.001 pH. When triangular pulses are applied to the input, the duration of the output pulses decreases linearly with increasing pH. The characteristics of the studied structure are almost linear in the studied pH range. The output voltage may be immune to the individual sensitivity of single transistors, the leakage current and power consumption are quite low. The considered methodology opens up an effective approach to scaling the pH sensor, providing high resolution with minimal power consumption. At the same time, high sensitivity and linear conversion of the output current to the output voltage can be achieved. This opens the way for the effective integration of complementary sensors into an analytical laboratory on a chip.

Masalsky N.V. An effective method of pH-metry based on a complementary scheme of ion-sensitive nanotransistors. Biomedicine Radioengineering. 2025. V. 28. № 3. P. 60–69. DOI: https:// doi.org/10.18127/j15604136-202502-07 (In Russian)

1. Functional nanomaterials and devices for electronics, sensors and energy harvesting. by ed. Flandre D, Springer International Publi­shing Switzerland 2014. 467.
2. Hübert T., Boon-Brett L., Buttner W. Sensors for safety and process control in hydrogen technologies. CRC Press, 2015. 414.
3. Rocchitta G., Spanu A., Babudieri S., Latte G., Madeddu G., Galleri G., Nuvoli S., Bagella P., Demartis M.I., Fiore V., Manetti R., Serra P.A. Enzyme biosensors for biomedical applications: strategies for safeguarding analytical performances in biological fluids. Sensors. 2016. V. 16. № 6. P. 780–802.
4. Paulovich F.V., de Oliveira M.C.F., Oliveira O.N., Jr. A future with ubiquitous sensing and intelligent systems. ACS Sens. 2018. V. 3. № 8. P. 1433–1438.
5. Buttner W.J., Post M., Burgess R., Rivkin C. An overview of hydrogen safety sensors and requirements. Int. J. Hydrogen Energy. 2011. V. 36. № 3. P. 2462–2470.
6. Hübert T., Boon-Brett L., Black G., Banach U. Hydrogen sensors. A review. Sens. Actuators B Chem. 2011. V. 157. P. 329–352.
7. Adeel M., Rahman M., Caligiuri I., Canzonieri V., Rizzolio F., Daniele S. Recent advances of electrochemical and optical enzyme-free glucose sensors operating at physiological conditions. Biosensors and Bioelectronics. 2020. V. 165. P. 112331.
8. Zeng J., Kuang L., Miscourides N., Georgiou P. A 128×128 current-mode ultra-high frame rate ISFET array with in-pixel calibration for real-time ion imaging. IEEE Trans. Biomed. Circuits Syst. 2020. V. 14. P. 359–372.
9. Gale B.K., Jafek A.R., Lambert C.J., Goenner B.L., Moghimifam H., Nze U.C., Kamarapu S.K. A review of current methods in microfluidic device fabrication and future commercialization prospects. Inventions. 2018. V. 3. № 3. P. 60–68.
10. Rigante S., Scarbolo P., Wipf M., Stoop R.L., Bedner K., Buitrago E., Bazigos A., Bouvet D., Calame M., Schönenberger C. Sensing with advanced computing technology: fin field-effect transistors with high-k gate stack on bulk silicon. ACS Nano. 2015. V. 9. № 5. P. 4872–4881.
11. Tran D., Winter M., Yang C.-T., Stockmann B., Offenhäusser A., Thierry B. Silicon nanowires field effect transistors: A comparative sensing performance between electrical impedance and potentiometric measurement paradigms. Anal. Chem. 2019. V. 91. № 19. P. 12568–12573.
12. Biomaterials nanoarchitectonics. Ebara M. (editor). Elsevier Inc. 2016. 362.
13. Ferain I, Colinge C.A, Colinge J. Multigate transistors as the future of classical metal–oxide–semiconductor field-effect transistors. Nature. 2011. V. 479. P. 310–316.
14. Naresh V., Lee N. A review on biosensors and recent development of nanostructured materials-enabled biosensors. Sensors. 2021. V. 21. № 4. P. 1109.
15. Manjakkal L., Szwagierczak D., Dahiya R. Metal oxides based electrochemical pH sensors: Current progress and future perspectives. Prog. Mater. Sci. 2020. V. 109. P. 100635–100642.
16. Chan W.P., Premanode B., Toumazou C. An integrated ISFETs instrumentation system in standard CMOS technology. IEEE Solid-State Circuits. 2010. V. 45. P. 1923–1934.
17. Do A., Je M., Yeo K. An improved inverter‑based readout scheme for low‑power ISFET sensing array. Electronics Letters. 2013. V. 49. P. 1517–1518.
18. Zhou Q., Son K., Liu Y., Revzin A. Biosensors for cell analysis. Annu Rev Biomed Eng. 2015. V. 17. P. 165–190.
19. Moser N., Lande T.S., Toumazou C., Georgiou P. ISFETs in CMOS and emergent trends in instrumentation: A review. IEEE Sens. J. 2016. V. 16. P. 6496–6514.
20. Lundström I., Shivaraman, S., Svensson C., Lundkvist L. A hydrogen-sensitive MOS field-effect transistor. Appl. Phys. Lett. 1975. V. 26. P. 55–57.
21. Lundström I. Hydrogen sensitive MOS-structures, Part I: Principles and applications. Sens. Actuators. 1981. V. 1. P. 423–426.
22. Masalsky N. Silicon on isolator ribbon field-effect nanotransistors for high-sensitivity low-power biosensors. J. Eng. Technol. Sci. 2022. V. 54. P. 435–448.
23. Shafi N., Sahu C., Periasamy C. Fabrication and pH sensitivity analysis of in-situ doped polycrystalline silicon thin-film junctionless BioFET. IEEE Electron Device Lett. 2019. V. 40. № 6. P. 997–1000.
24. TCAD Sentaurus Device https://www.synopsys.com/silicon/tcad/device-simulation/sentaurus-device.hlmt/ (дата обращения 02.03.2021).
25. Wong H.Y., Braga N., Mickevicius R.V. Prediction of highly scaled hydroden-terminated diamond MISFET performance based on calibrated TCAD simulation. Diam. Relat. Mater. 2017. V. 80. P. 14–17.
26. Dinar A., Zain A., Salehuddin F., Attiah M., Abdulhameed M. Modeling and simulation of electrolyte pH change in conventional ISFET using commercial Silvaco TCAD. IOP Conf. Mater. Sci. Eng. 2019. P. 518–522.
27. Nguyen N., Readout T.C. Concepts for label-free biomolecule detection with advanced ISFET and silicon nanowire biosensors. Technische Universität Kaiserslautern. Kaiserslautern. Germany. 2018. 176.
28. Masalskii N.V. Compact sensor on the basis of the «silicon on isolator» waveguide structure for express detecting of ammonia solution. International Journal of Biosensors and Bioelectronics. 2018. V. 4. № 1. P. 27–28.
29. Hu Y., Moser N., Georgiou P. A 32×32 ISFET chemical sensing array with integrated trapped charge and gain compensation. IEEE Sens. J. 2017. V. 17. P. 5276–5284.