A6300 camera

The scanning electron micrographs were obtained using a Hitachi TM3000 microscope equipped with a back-scattered electron detector at an acceleration voltage of 15 kV. The cross-section samples were obtained by first cooling down the samples by immersing them into boiling liquid nitrogen and then sliced using a cooled scalpel blade. The silk fibers were false-colored for visual guidance.
The optical micrographs were acquired using a Sony A6300 camera with a 10 × objective; the field-of-depth was enhanced using the focus-stacking technique in Picolay software.
The electrochemical impedance of the laminate was measured using a BioLogic BP-300 potentiostat/galvanostat/FRA in two-electrode mode.
Actuation was measured by generating voltage waveforms using National Instruments’ PCI-6036E DAQ device and LabVIEW programming environment. The output current was amplified using an OPA548T operational amplifier in the voltage-follower configuration. The actuation was registered using a Keyence LK-G82/LK-G3001P laser displacement meter.
Spring-loaded clamps with contacts made of gold were used for actuation and impedance measurement.
The actuator material was characterized at room temperature (≈22°C) and relative humidity about 50%.

For each archaeological object we recorded the raw material (bone or antler), tool type, maximum length, maximum width, maximum thickness, number of barbs, presence of broken, damaged, and reworked barbs, barb incision shape, base morphology, and base cross-section accordingly to previous classifications [27 ,29 ]. The identification of the raw material was based on optical examination of the inner material surface and comparison with bone and antler natural and modified fragments from the reference collection of the Laboratory for Material Cultural Studies (Leiden University, NL).
We created 3D models using close-range photogrammetry to create a permanent record of the points selected for destructive analysis and points with relevant hafting traces (S2). Pictures were taken with a Sony A6300 camera equipped with a 50 mm lens. The points were placed on a hand-operated turntable and manually photographed. The smaller objects (NSM1, 6, 9, 19) were photographed at two different height stages. One image every 5° was captured for each face, totally 72 per whole rotation. The larger objects (NSM10, 16, 30) were photographed at three height stages for each face. For large points, a whole rotation comprised 45 photographs, one every 8°. The images were processed, and high-resolution models were created and properly scaled in Agisoft Metashape 1.6.5.

For excised rosette, leaves were sequentially removed and the length, width, and thickness of the basal and middle regions of each leaf were measured. Anatomical examinations were carried out on selected leaves of different ages (in case of a rosette, the leaf position is equivalent to the leaf age) using hand-cut cross sections and 40–60 µm thick sections made with a core-microtome (WSL, Birmensdorf, Switzerland). The sections were stained with safranin O (Roth) and astra blue (Roth) [v/v; 1:1], dehydrated in ethanol (50–100%) and mounted in Euparal (Roth). Stained sections were examined in transmitted light with an Olympus BX41 microscope. Pictures of cross sections were taken with a Sony A6300 camera. Unstained, hand-cut, cross sections of the middle leaf region were examined under UV light with an LED fluorescence Zeiss Axio.Lab1 microscope, equipped with a camera (Opta-Tech, Poland). Some hand-cut cross sections were also examined using the FEI Quanta 200 ESEM scanning electron microscope with the EDS EDAX analyser. Electron microscope observations and photos were taken in low vacuum mode (up to 1Tr).