Biosensors and Bioelectronics, Volume 40, Issue 1, 15 February 2013, Pages 323-328.
Islam Bogachan Tahirbegi, Mònica Mir, Josep Samitier.
Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain AND
Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Maria de Luna, 11, 50018 Zaragoza, Spain AND
Department of Electronics, Barcelona University (UB), Martí I Franques, 1, Barcelona 08028, Spain.
The low pH in the gastric juice of the stomach makes it difficult to fabricate stable and functional all-solid-state pH ISE sensors to sense ischemia, mainly because of anion interference and adhesion problem between the ISE membrane and the electrode surface. In this work, the adhesion of ISE membrane on solid surface at low pH was improved by modifying the surface with a conductive substrate containing hydrophilic and hydrophobic groups. This creates a stable and robust candidate for low pH applications. Moreover, anion interference problem at low pH was solved by integration of all-solid-state ISE and internal reference electrodes on an array. So, the same tendencies of anion interferences for all-solid-state ISE and all-solid-state reference electrodes cancel each other in differential potentiometric detection. The developed sensor presents a novel all-solid-state potentiometric, miniaturized and mass producible pH ISE sensor for detecting ischemia on the stomach tissue on an array designed for endoscopic applications.
Microelectronic devices has increased its important role in the last decade, mainly focused in electronic sensors for different applications. All solid- state ion selective electrode (ISE) sensors, permits the selective and sensitive detection of ions, which make them usefull in different fields. Moreover, the low cost and easy miniaturisation of this kind of sensors makes them an attarctive device for analysis.
In this work a novel all-solid-state potentiometric, miniaturized and mass producible pH ISE sensor for detecting ischemia at low pHs was successfully fabricated on an array designed for its insertion inside the stomach by means of an endoscopic device.
The high acidity and corrosivity of the gastric juice on the stomach makes difficult to fabricate stable and functional sensors for detection on this tissue. Mainly, the anion interference and the adhesion problem between the ISE membrane and the electrode surface are the key problems encountered in the development of this ISE sensor for stomach detection.
In this paper, the adhesion of ISE membrane on solid surface at low pH was improved by modifying the surface with conductive substrate containing hydrophilic and hydrophobic groups, which are less affected by the ionization changes at different pHs. There are other physical and chemical approaches to improve ISE adhesion, however our method requires fewer fabrication steps and reduces the cost of sensor preparation. Anion interference problem at low pH was solved by using the same electrode material for the electrode substrate of the all-solid-state ISE and the reference electrode. In this way, the ion interference affects RE and ISE in the same manner, being cancelled by the differential potentiometric measurement. Moreover, subnernstian behavior of all-solid-state pH sensor was fixed by the enhancement of KTCIPB concentration in ISE membrane. However, the increase in sensitivity is affected by a worse interference of cations, being reduced the selectivity of the sensor.
Reproducibility studies of the fabricated all-solid-state ISE integrated with the all-solidstate RE were performed demonstrating good reproducibility of the sensors fabricated in the same array as well as different arrays.