Field-effect sensors for monitoring the layer-by-layer adsorption of charged macromolecules

University of Applied Sciences Aachen, Division Jülich, Laboratory for Chemical Sensors and Biosensors, Ginsterweg 1, 52428 Jülich, Germany
Sensors and Actuators B Chemical (Impact Factor: 4.1). 10/2006; 118:163-170. DOI: 10.1016/j.snb.2006.04.013


Capacitive EIS (electrolyte–insulator–semiconductor) sensors and ISFETs (ion-sensitive field-effect transistor) have been utilised for the detection of the layer-by-layer adsorption of charged macromolecules. The field-effect-based sensors with the adsorbed multilayers have been characterised by capacitance–voltage, constant-capacitance and constant-voltage-mode methods. The effect of the number and polarity of the polyelectrolyte layers on the shift of the capacitance–voltage curves along the capacitance and voltage axis has been investigated. Alternating potential shifts of about 30–50 mV have been observed after the adsorption of each polyanion and polycation layer, respectively. The possible mechanisms for the sensor response are discussed.

Download full-text


Available from: Arshak Poghossian, Aug 07, 2014
  • Source
    • "In development of solid state sensor, recent approaches are ISFET (ion-sensitive field effect transistor), LAPS (light addressable potentiometric sensor), and capacitance-based electrolyte insulator semiconductor (EIS) [1-4]. Among these developments, EIS has shown potential in terms of its simple structure, label-free detection, easy fabrication procedure, and cost effectiveness [5,6]. In addition, nanoparticles have generated considerable interest as diagnostic tool because of their small sizes and comparatively higher surface area that leads to more interaction with ions in solution [7-10]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Time-dependent pH sensing phenomena of the core-shell CdSe/ZnS quantum dot (QD) sensors in EIS (electrolyte insulator semiconductor) structure have been investigated for the first time. The quantum dots are immobilized by chaperonin GroEL protein, which are observed by both atomic force microscope and scanning electron microscope. The diameter of one QD is approximately 6.5 nm. The QDs are not oxidized over a long time and core-shell CdSe/ZnS are confirmed by X-ray photon spectroscopy. The sensors are studied for sensing of hydrogen ions concentration in different buffer solutions at broad pH range of 2 to 12. The QD sensors show improved sensitivity (38 to 55 mV/pH) as compared to bare SiO2 sensor (36 to 23 mV/pH) with time period of 0 to 24 months, owing to the reduction of defects in the QDs. Therefore, the differential sensitivity of the QD sensors with respect to the bare SiO2 sensors is improved from 2 to 32 mV/pH for the time period of 0 to 24 months. After 24 months, the sensitivity of the QD sensors is close to ideal Nernstian response with good linearity of 99.96%. Stability and repeatability of the QD sensors show low drift (10 mV for 10 cycles) as well as small hysteresis characteristics (<10 mV). This QD sensor is very useful for future human disease diagnostics.
    Full-text · Article · Apr 2014 · Nanoscale Research Letters
  • Source
    • "The sensitive layer consists of a Ta O film deposited on top of an extended gate, and corresponds to the part of the device that is actually submersed in the electrolyte solutions. Ta O has a high surface buffer capacity which is ideal for achieving maximum sensitivity [1] being one of the more stable materials used as sensitive layer for pH, enzymes, and DNA [7], [20]–[22]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We present the results obtained with an extended-gate ISFET totally based on amorphous oxides (GIZO as the semicon-ductor, Ta O :SiO as the dielectric and Ta O as the sensitive layer). A full characterization of the device was performed with constant ionic strength pH buffer solutions, revealing a sensitivity of 40 mV/pH with small hysteresis, and good linearity in the pH 4–pH 10 range buffer solutions. These results clearly show that it is possible to produce room-temperature disposable and low cost bio-sensors.
    Full-text · Article · Sep 2013 · Journal of Display Technology
  • Source
    • "Consequently, the direction of the potential change after adsorption of negatively charged SWNTs corresponds to the case as if the Ta O surface would have been additionally negatively charged. Similar effects were reported for a polyelectrolyte multilayer formation onto a p-Si-SO [30], [31] and a p-Si-SO -diamond [32] capacitive EIS sensor. Before the noise experiments, the gate-leakage current and the pH sensitivity of bare and functionalized p-Si-SiO -Ta O sensors have been examined. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Low-frequency noise in an electrolyte-insulator-semiconductor (EIS) structure functionalized with multilayers of polyamidoamine (PAMAM) dendrimer and single-walled carbon nanotubes (SWNT) is studied. The noise spectral density exhibits dependence with the power factor of and for the bare and functionalized EIS sensor, respectively. The gate-voltage noise spectral density is practically independent of the pH value of the solution and increases with increasing gate voltage or gate-leakage current. It has been revealed that functionalization of an EIS structure with a PAMAM/SWNTs multilayer leads to an essential reduction of the noise. To interpret the noise behavior in bare and functionalized EIS devices, a gate-current noise model for capacitive EIS structures based on an equivalent flatband-voltage fluctuation concept has been developed.
    Full-text · Article · Feb 2011 · IEEE Sensors Journal
Show more