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@INPROCEEDINGS{Lettinga:1048939,
      author       = {Lettinga, M.P. and Dahlhoff, Knut and Gottschalk, Simon},
      title        = {{I}ntroduction of {N}ew {R}otational {M}ini-{R}heometer for
                      {S}carce {S}ample},
      reportid     = {FZJ-2025-05036},
      year         = {2025},
      abstract     = {We introduce a miniaturized stress-controlled rheometer,
                      aimed at enhancing rotational rheometry for analysis of
                      scarce samples. This innovative device addresses the
                      critical need for analyzing samples, such as biofilms,
                      nascent drug formulations, and rare metal inks for
                      microelectronics, which are typically limited in quantity
                      due to their high production costs, challenging synthesis,
                      or exclusive origins. Rheological measurements typically
                      require at least 20 µl of sample material using commercial
                      rotation rheometer, a requirement significantly reduced by
                      our device, whereas the employed cone-plate geometry only
                      requires 2 µl of sample material, representing a
                      significant advancement in sample conservation. The
                      mini-rheometer, approximately the size of a 50mm cube,
                      utilizes an air bearing rotor made of quartz glass,
                      manufactured via Selective Laser Etching (SLE). This
                      subtractive 3D printing method for glass ensures the
                      precision needed for an air bearing with µm-scale gaps. An
                      outer magnetic field drives a centrally-placed magnet, while
                      the angular displacement is accurately gauged by two Hall
                      effect sensors, that detect the rotational movement of the
                      inner magnet. The mini-rheometer´s efficiency and
                      functionality were tested on calibration fluids, from water
                      to viscous oils, as well as biological samples, such as
                      percolating blood. This development extends the benefits of
                      rotational rheometry – such as a wide range of strain
                      rates and homogeneous strain profiles – to experiments
                      where sample availability is limited. Due to the device´s
                      miniaturized dimensions common, inverted microscopes can be
                      used to study microstructural properties related to
                      macroscopic flow behavior, which we used for the biological
                      samples.},
      month         = {Sep},
      date          = {2025-09-25},
      organization  = {International Soft Matter Conference,
                       Chania, Crete (Greece), 25 Sep 2025 - 3
                       Oct 2025},
      subtyp        = {After Call},
      cin          = {IBI-4},
      cid          = {I:(DE-Juel1)IBI-4-20200312},
      pnm          = {5243 - Information Processing in Distributed Systems
                      (POF4-524)},
      pid          = {G:(DE-HGF)POF4-5243},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1048939},
}