Fig 1.
(A) Platform assembly showing subassemblies, (B) precision micrometer actuator subassembly and components. Further details of the actuation mechanism are illustrated in Fig 2.
Fig 2.
Motion transfer interface, (A) a subset of the actuator tower; (B) a side view of the actuator tower; (C) a cross-section side view showing the camshafts in green and their X-axis motion in arrows; (D) actual assembled device, (E) a side view of the assembly, manipulator(grey) and end effectors (red); (F) a cross-section side view of the assembly showing the actuator to manipulator contact, where camshafts are shown in (green), manipulator in (grey), and the end effectors in (red); and (G) a cross-section side view COMSOL simulation showing the delivered motion profile of the actuation. (H) Actuator-manipulator-end effector repeated motion performance (with no sample). The delivered motion linearity is tared at step 2 (R2 = 0.99).
Fig 3.
(A-H) micromachined acrylic molds for PDMS parts and installation jigs as labeled; and (I-L) are the cured PDMS outcomes of the parts above it. The cantilevers (I) and manipulator (J) are assembled into a single piece (K), while (L) shows the arrayed PDMS mold used for hydrogel arrayed pillar generation. The whitish face shown in the image (L) is the side that was in contact with the machined side of mold (H).
Fig 4.
(Steps 1–10) Hydrogel casting/molding protocol.
(A) the PDMS mold showing the non-machined, shiny side; (B) acrylic leveler which had a smooth surface and sufficient weight was used to force excess hydrogel to the sides (step 7); (C) After the leveler was removed, media was added (step 9); (D) PDMS mold was the peeled off, and arrayed hydrogel pillars are ready for mechanical testing shown in (E).
Fig 5.
The viability of HDF in a 24 well-plate and stained for fluorescence observation after cultured in monolayers for three weeks in a chamber closed with the PDMS manipulator.
(A) the dead cells in red (Texas red filter), (B) the live cells in green (FITC filter), and (C) stain bound to HDF nuclei DNA (DAPI).
Fig 6.
The end effectors (cantilevers) deflections with and without a sample; (A-C) sides views of (A) the contact point, (B) the cantilever bending (with a sample); and (C) the cantilever displacement (without a sample). (D-F) bottom views of (D) the contact point, (B) the cantilever bending (with a sample), and (C) the cantilever displacement (without a sample).
Fig 7.
Finding the cantilever-sample contact and measuring the following indentation.
Once the cantilevers engage with the sample, a change in the slope is observed and recorded. In this measurement, Step 3 (Taring point shown in green) was the sample contact point where the displacement measurement started. Step 20 (red) was the cut-off strain limit considering the end-effectors’ calibration linear range and the targeted strain applied to samples.
Fig 8.
The four tested groups of hydrogel organoids, (A) control—day 0, without cells; (B) SKOV3 embedded organoids- day 0; (C) control—day 5; and (D) SKOV3 embedded organoids- day5.
Fig 9.
Stiffness measurements across the four groups, (A) displays the force curves, and the average measured stiffness in (nN/μm) with standard deviations plotted in linear fittings; (B) the four groups’ stiffness in (N/m) with statistical analysis, where (p-values < 0.05) were assigned (*).
Fig 10.
(A) The diameter changes across the four groups, while (B) is the elastic modulus calcualted based on the relative reference measurement conducted in typical parallel-plate compression (PPC) in combination with stiffness measurements.