Surface Potential Sensor

The KSV NIMA Surface Potential Sensor is a compact and highly sensitive characterization instrument that offers complementary data on the packing and orientation of Langmuir films. The KSV NIMA Surface Potential Sensor (SPOT) measures the potential difference above and below the film.

Features & Benefits

  • Accurate and reproducible measurements. The non-contact and non-destructive vibrating plate capacitor method ensures excellent accuracy and reproducibility.
  • Software integrated to the KSV NIMA L and LB Trough Software. The KSV NIMA Surface Potential Sensor does not require any additional software and can be easily installed by a simple plug and play operation. The latest version of KSV NIMA LB Software, supplied with all KSV NIMA Langmuir and Langmuir-Blodgett Deposition Troughs, displays the recordings of the surface pressure and surface potential on the same plot. Color-coded axes and plots ensure that the two recordings are clearly presented.
  • Easy set up. The KSV NIMA Surface Potential Sensor connects directly to your existing KSV NIMA Interface Unit, supplied with all KSV NIMA Langmuir and LB Deposition Troughs. The sensor has a flexible stand allowing rapid and easy integration with a trough. Furthermore, the sensor is factory calibrated for a quick start up.


  • Determining effective dipole moments. The sensor can be used to determine effective dipole moments through simple surface potential measurements of a compressed film.
  • Determining molecular orientation. The provides information about molecular orientation by observing changes in surface potential and combining the data with surface pressure information.
  • Film electronic structure characterization. Small changes in the electronic structure of molecules can be detected by measuring the change in surface potential.
  • Molecular structure characterization. Quantify the effects of changes to molecular structure through positional offsets and peak values of the surface potential plots.
  • Complex formation monitoring. Observe and follow complex formations between monolayers, sub-phase species or adsorbates.

Product details

The KSV NIMA Surface Potential Sensor measures the potential difference above and below the film and is sensitive to the sum of all the individual dipole moments. The changes in surface potential are measured by detecting the potential difference between the vibrating plate, which is placed above the monolayer, and the counter electrode, which is immersed in the sub-phase below the monolayer.

The sensor allows complementing data from surface pressure—area isotherm measurements obtained from a Langmuir and Langmuir-Blodgett Trough. It allows the determination of monolayer composition, molecular orientation, degree of molecular dissociation and molecular interactions at the interface.

The KSV NIMA Surface Potential Sensor is recommended for use with a KSV NIMA Langmuir, Langmuir-Blodgett or a Microscopy Trough to enable combined surface pressure and surface potential measurements. The KSV NIMA Surface Potential Sensor can also be used with other troughs together with a KSV NIMA Interface Unit. See more details in our compatibility chart below.

ISR High Compression
Alternate Large

For the full table, see:


Application examples

The interaction of an antiparasitic pep­tide with cell membrane models

In drug discovery the permeation of the drug into cells through cell walls and the reac­tion of the drug within the cell membrane are important factors for drug efficiency. In this example, a drug candidate for the Human African Sleeping Sickness (HAT) was studied in vitro in a model cell membrane.

The oligopeptide-based drug S-(2,4-dinitrophenyl) glutath­ione di-2-propyl ester, has shown activity in the treatment of HAT and was studied in Langmuir monolayer model membrane of DPPC (dipalmitoyl phosphorylcholine), an abundant lipid in the protozoan membrane. The monolayer properties of the drug itself and its interactions with DPPC monolayers were studied with Langmuir equipment (KSV NIMA Langmuir Trough) with a surface potential meter (KSV NIMA SPOT) and polarization modula­tion surface infrared reflection absorption spectrometer (KSV NIMA PM-IRRAS). 

For more information, see: 

Surface pressure-area and surface potential-area isotherms of a HAT-drug monolayer at air-buffer interface.


  1. Pascholati et al., ‘Colloids and Surfaces B: Biointerfaces’ 74 (2009) 504–510
  2. Kim et al., ‘J of American Chemical Society’ (2010), 132, pp. 8180-8186