TY  - JOUR
A1  - Molinnus, Denise
A1  - Iken, Heiko
A1  - Johnen, Anna Lynn
A1  - Richstein, Benjamin
A1  - Hellmich, Lena
A1  - Poghossian, Arshak
A1  - Knoch, Joachim
A1  - Schöning, Michael Josef
T1  - Miniaturized pH-Sensitive Field-Effect Capacitors with Ultrathin Ta₂O₅ Films Prepared by Atomic Layer Deposition
JF  - physica status solidi (a) applications and materials science
N2  - Miniaturized electrolyte–insulator–semiconductor capacitors (EISCAPs) with ultrathin gate insulators have been studied in terms of their pH-sensitive sensor characteristics: three different EISCAP systems consisting of Al–p-Si–Ta2O5(5 nm), Al–p-Si–Si3N4(1 or 2 nm)–Ta2O5 (5 nm), and Al–p-Si–SiO2(3.6 nm)–Ta2O5(5 nm) layer structures are characterized in buffer solution with different pH values by means of capacitance–voltage and constant capacitance method. The SiO2 and Si3N4 gate insulators are deposited by rapid thermal oxidation and rapid thermal nitridation, respectively, whereas the Ta2O5 film is prepared by atomic layer deposition. All EISCAP systems have a clear pH response, favoring the stacked gate insulators SiO2–Ta2O5 when considering the overall sensor characteristics, while the Si3N4(1 nm)–Ta2O5 stack delivers the largest accumulation capacitance (due to the lower equivalent oxide thickness) and a higher steepness in the slope of the capacitance–voltage curve among the studied stacked gate insulator systems.
KW  - atomic layer deposition
KW  - capacitive field-effect sensors
KW  - pH sensors
KW  - ultrathin gate insulators
Y1  - 2022
U6  - http://dx.doi.org/10.1002/pssa.202100660
SN  - 1862-6319
VL  - 219
IS  - 8
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Molinnus, Denise
A1  - Janus, Kevin Alexander
A1  - Fang, Anyelina C.
A1  - Drinic, Aleksander
A1  - Achtsnicht, Stefan
A1  - Köpf, Marius
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Thick-film carbon electrode deposited onto a biodegradable fibroin substrate for biosensing applications
JF  - Physica status solidi (a)
N2  - This study addresses a proof-of-concept experiment with a biocompatible screen-printed carbon electrode deposited onto a biocompatible and biodegradable substrate, which is made of fibroin, a protein derived from silk of the Bombyx mori silkworm. To demonstrate the sensor performance, the carbon electrode is functionalized as a glucose biosensor with the enzyme glucose oxidase and encapsulated with a silicone rubber to ensure biocompatibility of the contact wires. The carbon electrode is fabricated by means of thick-film technology including a curing step to solidify the carbon paste. The influence of the curing temperature and curing time on the electrode morphology is analyzed via scanning electron microscopy. The electrochemical characterization of the glucose biosensor is performed by amperometric/voltammetric measurements of different glucose concentrations in phosphate buffer. Herein, systematic studies at applied potentials from 500 to 1200 mV to the carbon working electrode (vs the Ag/AgCl reference electrode) allow to determine the optimal working potential. Additionally, the influence of the curing parameters on the glucose sensitivity is examined over a time period of up to 361 days. The sensor shows a negligible cross-sensitivity toward ascorbic acid, noradrenaline, and adrenaline. The developed biocompatible biosensor is highly promising for future in vivo and epidermal applications.
KW  - biocompatible materials
KW  - biodegradable electronic devices
KW  - biosensors
KW  - carbon electrodes
KW  - glucose
Y1  - 2022
U6  - http://dx.doi.org/10.1002/pssa.202200100
SN  - 1862-6319
N1  - Corresponding author: Michael J. Schöning
VL  - 219
IS  - 23
SP  - 1
EP  - 9
PB  - Wiley-VCH
CY  - Weinheim
ER  -