• Explaining doping in material research (Hf substitution in ZnO films) by directly quantifying the van der Waals force 

      Lai, Chia-Yun; Santos Hernandez, Sergio; Moser, Toni; Alfakes, Boulos; Lu, Chun-Yu; Olukan, Tuza Adeyemi; Rajput, Nitul; Boström, Tobias; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-04)
      Non-monotonic behavior has been observed in the optoelectronic properties of ZnO thin films as doped with Hf (HZO). Here we propose that two competing mechanisms are responsible for such behaviour. Specifically, we propose that provided two crystal orientations dominate film growth, only one of them might be responsible for direct Hf substitution. Nonmonotonic behaviour is expected at once by ...
    • Hydration dynamics and the future of small-amplitude afm imaging in air 

      Santos Hernandez, Sergio; Olukan, Tuza Adeyemi; Lai, Chia-Yun; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-23)
      Here, we discuss the effects that the dynamics of the hydration layer and other variables, such as the tip radius, have on the availability of imaging regimes in dynamic AFM—including multifrequency AFM. Since small amplitudes are required for high-resolution imaging, we focus on these cases. It is possible to fully immerse a sharp tip under the hydration layer and image with amplitudes similar to ...
    • Insights into TiO<inf>2</inf>thin film photodegradation from Kelvin Probe AFM maps 

      Olukan, Tuza Adeyemi; Sydorenko, Jekaterina; Katerski, Atanas; Al Mahri, Mariam; Lai, Chia-Yun; Al-Hagri, Abdulrahman; Santos Hernandez, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-29)
      The synthesis of TiO2 thin films by the chemical spray pyrolysis method at different titanium isopropoxide (TTIP) to acetylacetone (AcacH) ratios has been shown to lead to the highest photodegradation at 1 (TTIP):8 (AcacH). These films hold promise in the field of indoor pollution treatment. Carbon incorporation into the surface and into the TiO2 lattice could be responsible for the observed ...
    • Investigating the Ubiquitous Presence of Nanometric Water Films on Surfaces 

      Santos Hernandez, Sergio; Amadei, Carlo Alberto; Lai, Chia-Yun; Olukan, Tuza Adeyemi; Lu, Jin-You; Font, Josep; Barcons, Victor; Verdaguer, Albert; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-25)
      When we speak of nanometric water films on surfaces we are speaking about a truly ubiquitous phenomenon in nature. All surfaces exposed to ambient conditions are covered by a thin film of water that affects or mediates surface chemistry, general physical-chemical processes on surfaces, and even solid–solid interactions. We have investigated this phenomenon for over a decade by exploiting dynamic ...
    • Machine learning assisted multifrequency AFM: Force model prediction 

      Elsherbiny, Lamiaa; Santos Hernandez, Sergio; Gadelrab, Karim; Olukan, Tuza; Font, Josep; Barcons, Victor; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-05)
      Multifrequency atomic force microscopy (AFM) enhances resolving power, provides extra contrast channels, and is equipped with a formalism to quantify material properties pixel by pixel. On the other hand, multifrequency AFM lacks the ability to extract and examine the profile to validate a given force model while scanning. We propose exploiting data-driven algorithms, i.e., machine learning packages, ...
    • Predicting the suitability of lateritic soil type for low cost sustainable housing with image recognition and machine learning techniques 

      Olukan, Tuza Adeyemi; Chiou, Yu-Cheng; Chiu, Cheng-Hsiang; Lai, Chia-Yun; Santos Hernandez, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-10)
      From a sustainability point of view, laterites-compressed earth bricks (LCEB) are a promising substitute for building structures in place of the conventional concrete masonry units. On the other hand, techniques for identifying and classifying laterites soil for compressed earth bricks (CEB) production are still relying on direct human expertise or ‘experts’. Human experts exploit direct visual ...
    • Probing power laws in multifrequency AFM 

      Santos Hernandez, Sergio; Gadelrab, Karim; Olukan, Tuza Adeyemi; Font, Josep; Barcons, Victor; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-17)
      Quantification of conservative forces in multifrequency atomic force microscopy requires solving the general equations of the theory expressed in terms of the virials of interaction. Power law expressions are commonly utilized when dealing with electrostatic, ferroelectric, magnetic, or long range (van der Waals) forces. Here, we discuss long range forces modeled in terms of power laws (n), where ...
    • Quantification of van der Waals forces in bimodal and trimodal AFM 

      Santos Hernandez, Sergio; Gadelrab, Karim; Elsherbiny, Lamiaa; Drexler, Xaver; Olukan, Tuza Adeyemi; Font, Josep; Barcons, Victor; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-22)
      The multifrequency formalism is generalized and exploited to quantify attractive forces, i.e., van der Waals interactions, with small amplitudes or gentle forces in bimodal and trimodal atomic force microscopy (AFM). The multifrequency force spectroscopy formalism with higher modes, including trimodal AFM, can outperform bimodal AFM for material property quantification. Bimodal AFM with the second ...
    • Should humans work? 

      Santos Hernandez, Sergio; Kissamitaki, Maritsa; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-01)
      Should humans work? A simple question at a time when the advent of AI, automation and robotics claims a privileged position in the future of work. The question is perplexing and confusing however once we enquire into the meaning of technology and work as such: some claim that human jobs and well-being might be threatened by technological advances while others predict an increase in high skilled ...