Automated Drop-on-Fiber contact angle measurement using a microrobotic platform

Pooya Saketi, Juha Hirvonen, Yuli Lai, Christian Ganser, Christian Teichert, Joakim Järnström, Pedro Fardim, Pasi Kallio

    Research output: Contribution to journalArticleScientificpeer-review

    3 Citations (Scopus)


    Measuring contact angles on single fibers enables the separation of structural factors from surface chemistry factors. Current Drop-on-Fiber (DOF) contact angle measurement methods for natural fibers generally, and for pulp/paper fibers specifically, present a number of challenges. These are manipulation and mounting of the microscale fibers, straightening natural fibers to produce repeatable axisymmetric droplet conformation, measuring the droplet volume excluding the fiber volume and also human errors due to manually performed tasks. This paper presents a novel method to measure contact angles in DOF systems and overcome the above mentioned challenges using microrobots. The proposed microrobotic platform is capable of handling natural and synthetic fibrous materials in microscale, and dispensing probe liquid droplets down to 12 nl. It measures contact angle values using computer vision and a droplet-profile-detection algorithm. It reports the contact angle values as a function of volume of the droplet. The paper validates the capabilities of the proposed platform by applying three commonly used probe liquids: deionized water, ethylene glycol and diiodomethane for measuring contact angles on glass and pulp fibers. Finally, the results are compared with a picoliter contact angle measurement approach.
    Original languageUndefined/Unknown
    Pages (from-to)225–231
    Number of pages7
    JournalNordic Pulp and Paper Research Journal
    Issue number2
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed


    • Contact Angle
    • Drop-on-Fiber
    • Micromanipulation
    • Microrobotics
    • Pulp/Paper Fiber

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