Perception by Palpation: Development and Testing of a Haptic Ferrogranular Jamming Surface

Abstract

Tactile hands-only training is particularly important for medical palpation. Generally, equipment for palpation training is expensive, static, or provides too few study cases to practice on. We have therefore developed a novel haptic surface concept for palpation training, using ferrogranular jamming. The concept’s design consists of a tactile field spanning 260 x 160 mm, and uses ferromagnetic granules to alter shape, position, and hardness of palpable irregularities. Granules are enclosed in a compliant vacuum-sealed chamber connected to a pneumatic system. A variety of geometric shapes (output) can be obtained by manipulating and arranging granules with permanent magnets. The tactile hardness of the palpable output can be controlled by adjusting the chamber’s vacuum level. A psychophysical experiment (N = 28) investigated how people interact with the palpable surface and evaluated the proposed concept. Untrained participants characterized irregularities with different position, form, and hardness through palpation, and their performance was evaluated. A baseline (no irregularity) was compared to three irregularity conditions: two circular shapes with different hardness (Hard Lump and Soft Lump), and an Annulus shape. 100% of participants correctly identified an irregularity in the three irregularity conditions, whereas 78.6% correctly identified baseline. Overall agreement between participants was high (κ= 0.723). The Intersection over Union (IoU) for participants sketched outline over the actual shape was IoU Mdn = 79.3% for Soft Lump, IoU Mdn = 68.8% for Annulus, and IoU Mdn = 76.7% for Hard Lump. The distance from actual to drawn center was Mdn = 6.4 mm (Soft Lump), Mdn = 5.3 mm (Annulus), and Mdn = 7.4 mm (Hard Lump), which are small distances compared to the size of the field. The participants subjectively evaluated Soft Lump to be significantly softer than Hard Lump and Annulus. Moreover, 71% of participants thought they improved their palpation skills throughout the experiment. Together, these results show that the concept can render irregularities with different position, form, and hardness, and that users are able to locate and characterize these through palpation. Participants experienced an improvement in palpation skills throughout the experiment, which indicates the concepts feasibility as a palpation training device.

What the Mind Can Comprehend from a Single Touch

“…The study of the psychophysical perception of distributed pressure forces upon exploration by fingertips has long been of interest [7,[19][20][21][22][23]. Rørvik and co-authors [24] investigated whether untrained people could locate and determine by palpation the shapes and hardness of irregularities rendered between two compliant layers by using the ferrogranular jamming principle.…”

Robotic Simulators for Tissue Examination Training With Multimodal Sensory Feedback

“…hand bone protrusions palpation † † [83] Virtuose 6D Desktop, Haption; 3D printed haptic phantom hand 3D printed haptic phantom hand phantom hand 3D printed with stratasys printer (bone: VeroBlackPlus; tissue: a support-material (SUP) and TangoPlus filled metamaterial) sensorized abdominal phantom for palpation training [84] multi-layer abdominal model with controllable organ with positive granular jamming tumors also as sensors to detect palpation force and trajectory 5 controlled nodules (controlled between 30-55 kPa stiffness) within the silicone liver, tissue, and skin model; testing trial with linear indentation palpation showed an RMSE of 4 mm (in the testing area around 100 × 100 mm) and 1.18 N (for the applied force up to 18 N) for the position and force estimation of palpation, respectively. haptic surface † [85] tactile field with granular jamming of ferromagnetic granules to render shape, position, and hardness of palpable irregularities 260 x 160 mm; manipulated with permanent magnets haptic mouse † [86] a mouse type haptic display for localized physical abdomen simulation and interaction to a virtual abdomen different types of granular jamming and layer jamming mechanisms are tested to simulate the muscle guarding. granular jamming structures with soft, fine, and rigid granules, and layer jamming structures with stretchable and non-stretchable layers.…”

Vocal pain expression augmentation for a robopatient

“…Sensors are needed to capture important data during training sessions, actuators will be used to generate realistic responses, and algorithms are necessary to analyse the data and deliver the feedback in real time. Haptic feedback setups for palpation application range from modelling tumours using granular jamming ( Rørvik et al, 2021 ) to physical systems using interchangeable organs ( Rethy et al, 2018 ). Some physical simulators also produce visual cues, such as the physical–virtual hybrid face rendering pain facial expressions ( Lalitharatne et al, 2021 ).…”