*2.2. Instruments*

DataSpoon is an instrumented spoon (size: 19\*2\*1.5 cm, mass: 38 g; Figure 1a) which enables measurement of 6 Degrees of Freedom kinematic data and real-time presentation of movement via a smartphone app. A small, low cost wireless 3D accelerometer with gyroscope and magnetometer (red amber from GemSense, Haifa, Israel, see Table 1) is mounted at the proximal base of the spoon's handle, and a single CR2032 replaceable battery is mounted at the distal end of the spoon's handle. The raw 3D acceleration data and fused absolute orientation angles (in quaternions) were sampled at 50 Hz and transmitted via Bluetooth to a dedicated android smartphone and transformed to Excel files for o ffline processing. DataSpoon signals were compared to a "gold-standard" magnetic motion capture system (trakSTAR, Ascension Technology Corp., Shelburne, VT, USA, see Table 1). A trakSTAR sensor (Figure 1a) sampling at 200 Hz was attached to the center of the DataSpoon handle such that concurrent data was collected from both systems. The sensor's lightweight cable was attached with medical tape to the subject's forearm, allowing free movement of the spoon while minimizing the forces applied by the cable on the spoon.

**Figure 1.** (**a**) Experimental setup. DataSpoon was placed on a placemat pointing towards the distal end of the table. A smartphone captured real-time spoon movement. A trakSTAR sensor was located at the center of the spoon and connected to the trakSTAR box via a lightweight cable. (**b**) Natural grip. (**c**) Power grip. (**d**) Rotated power grip.


**Table 1.** Comparison of motion capture devices used in the study.
