the polymer that created our Tactile Fingertip™
The key to Ras Labs’ Tactile Fingertip™ sense of touch comes from our compliant electroactive polymers (EAPs). Ras Labs makes Synthetic Muscle™, which is a patented class of EAP-based materials and actuators that sense pressure (gentle touch to high impact), controllably contract and expand at low voltage (battery levels), and attenuate force [1,2]. Synthetic Muscle™ is a durable manmade material capable of life-like tactile sensing feedback and biomimetic motion, and able to withstand harsh environments: extreme temperatures, pressures, radiation (samples successfully flown on the International Space Station), and areas with contagions that have no cure. Ras Labs’ EAPs are scalable and can be made in a variety of shapes, sizes, thicknesses, and durometer. This is a strong material platform business that can lead to many applications; however, our current focus is providing human-like touch and feedback to robotic gripper end of arm tooling (EOAT) and automation.
Ras Labs’ Tactile Fingertips have been integrated into traditional marketplace grippers. These sensors generate immediate feedback at the first point of contact. Because these sensing pads provide a soft, compliant interface (they feel like human fingertips), the point of contact is gentle, yet also firm. The Tactile Fingertip also detects change in pressure location on its surface, making it possible to detect and prevent slippage by then adjusting the grip strength, proportionally in real time without stutter, due to both feedback and the sensing pad’s compliance. The soft gentle nature of our Tactile Fingertips naturally hold gripped objects, even delicate glassware and ripe fruit, with no droppage, no slippage, no damage, and leaving no marks.
The sensitivity of our sensor's electroactive polymer showcases a unique capability. Incredibly, the Tactile Fingertip has the ability to detect heartbeat pulses when humans hold the sensor with their fingers or against pulse points. Even more, the sensor can distinguish the four cardiac components within one heartbeat. These soft sensors are extremely sensitive, with a broad pressure range from at least 0.05 N up to 40 N with high linearity, and with a spatial resolution of 1 mm. Human touch is around 0.1 N of force over a fingertip [3] with a resolution of 2 mm [4]. We were aiming for human tactile touch and have surpassed this. Ras Labs’ soft compliant Tactile Fingertips are robust (10,000,000+ cycles with full functionality) while vastly sensitive and with a wide pressure range.
Ras Labs has the power to replicate human grasp. The combination of Ras Labs’ unique EAP based Tactile Fingertip™ sensing and Synthetic Muscle™ shape-morphing is expected to allow for the gentle handing of objects without having to sacrifice time, to reduce costly visualization, and promises the potential for robots with human hand-like tactile touch and dexterous control. This is expected to transform robotics, whether it is for E-commerce, unstructured bin sorting, agriculture, or manufacturing, as well as for collaborative robotics to allow humans and robots to work together intuitively and safely. ___________________________________________________________
1. L. Rasmussen, Editor, “Smart Materials: Considerations in Space and on Earth,” Springer, GmbH & Co. KG, pre-publication © 2021.
2. L. Rasmussen, Editor, “Electroactivity in Polymeric Materials,” Springer-Verlag, GmbH & Co. KG © 2012.
3. Patel B., Synthetic Skin Sensitive to the Lightest Touch, https://spectrum.ieee.org/biomedical/bionics/synthetic-skin-sensitive-to-the-lightest-touch © 2010.
4. Bickley, L. and Szilagui, P., “Bates' Guide to Physical Examination and History Taking (9th ed.),” Lippincott Williams & Wilkins, ISBN 978-0-7817-6718-7, ASIN B0028IKRYG © 2007.
