TY - JOUR
T1 - Pressure-Controlled Nanopipette Sensing in the Asymmetric-Conductivity Configuration
AU - Skaanvik, Sebastian A.
AU - Zhang, Xinyu
AU - McPherson, Ian J.
AU - Wang, Yuqing
AU - Larsen, Anne Kathrine K.
AU - Sønderskov, Steffan M.
AU - Unwin, Patrick R.
AU - Zambelli, Tomaso
AU - Dong, Mingdong
N1 - Publisher Copyright:
© 2025 American Chemical Society.
PY - 2025/4/8
Y1 - 2025/4/8
N2 - Nanopipettes are important tools across diverse disciplines, including biology, physics, and materials science. Precisely controlling their characteristics is crucial for many applications. Recent progress in this endeavor has involved using the asymmetric-conductivity configuration with different electrolyte solutions inside and outside the nanopipette, which can greatly improve nanopipette sensing. However, understanding such measurements remains challenging due to the complex interplay of diffusion, electromigration, and electroosmosis. Here, we systematically explore a fundamental regime of the asymmetric-conductivity configuration where classical ion current rectification due to ion-selective migration is minimized and the effect of electroosmotic flow is maximized. We characterized the current-potential and current-distance relationship and revealed that this experimental configuration exhibits many of the characteristics of traditionally rectifying nanopipettes, such as surface charge sensitivity, while the current response can be understood simply from the rate and direction of solution mixing due to electroosmotic flow. To optimize the sensitivity in the asymmetric-conductivity configuration, we introduced a method that uses external pressure to control the fluid flow rates at the aperture, tuning the local ionic environment in situ.
AB - Nanopipettes are important tools across diverse disciplines, including biology, physics, and materials science. Precisely controlling their characteristics is crucial for many applications. Recent progress in this endeavor has involved using the asymmetric-conductivity configuration with different electrolyte solutions inside and outside the nanopipette, which can greatly improve nanopipette sensing. However, understanding such measurements remains challenging due to the complex interplay of diffusion, electromigration, and electroosmosis. Here, we systematically explore a fundamental regime of the asymmetric-conductivity configuration where classical ion current rectification due to ion-selective migration is minimized and the effect of electroosmotic flow is maximized. We characterized the current-potential and current-distance relationship and revealed that this experimental configuration exhibits many of the characteristics of traditionally rectifying nanopipettes, such as surface charge sensitivity, while the current response can be understood simply from the rate and direction of solution mixing due to electroosmotic flow. To optimize the sensitivity in the asymmetric-conductivity configuration, we introduced a method that uses external pressure to control the fluid flow rates at the aperture, tuning the local ionic environment in situ.
KW - electroosmotic flow
KW - ion current rectification
KW - nanopipette
KW - scanning ion conductance microscopy
KW - scanning probe microscopy
KW - surface charge mapping
UR - https://www.scopus.com/pages/publications/105002692643
U2 - 10.1021/acsnano.4c16079
DO - 10.1021/acsnano.4c16079
M3 - Journal article
C2 - 40162623
AN - SCOPUS:105002692643
SN - 1936-0851
VL - 19
SP - 12853
EP - 12863
JO - ACS Nano
JF - ACS Nano
IS - 13
ER -