From Lotus Leaf to Laboratory: Using Nature’s Design

Traditional pressure sensors often struggle with accuracy. They have trouble giving consistent readings, often produce different results when the same pressure is applied repeatedly and can overlook subtle changes in pressure – all of which can lead to significant errors. They are also usually made from rigid and mechanically inflexible materials.

To address these challenges in pressure sensing, the NUS team drew inspiration from a phenomenon known as the ‘lotus leaf effect’ – a unique natural phenomenon where water droplets easily roll off the surface of a leaf, which is responsible for its small, water-sensitive effect. – Made possible by repulsive structures. By mimicking this effect, the team has fabricated a pressure sensor designed to significantly improve sensing performance.

“The sensor, similar to a miniature ‘potential meter’, can detect subtle pressure changes – mirroring the sensitivity of a lotus leaf to the very light touch of a water droplet,” explained Associate Professor Tee.

Employing an innovative ‘air spring’ design, the eAir sensor consists of a trapped layer of air, which forms an air-liquid interface when the sensor is in contact with the liquid. As the external pressure increases, this air layer gets compressed. The surface treatment results in frictionless movement of the interface within the sensor, thereby converting electrical signals that accurately reflect the applied pressure. Using this design, the natural water-repellent abilities of the lotus leaf have been re-imagined as a simple yet elegant pressure-sensing device.

Air devices can be made relatively small – a few millimeters in size – and are comparable to existing pressure sensors.

Potential game-changing advancement for minimally invasive surgery

The real world applications of this innovative technology are widespread. For example, in laparoscopic surgery where accurate tactile feedback is indispensable, the incorporation of the Air Sensor could make surgical procedures safer, ultimately increasing patient recovery and prognosis.

“Performing surgery with graspers presents its own unique challenges. Precise control and accurate perception of the applied forces are critical, but conventional tools can sometimes fall short, leaving surgeons to rely heavily on experience and even intuition. However, the introduction of soft and easily integrated air sensors could be a game-changer,” said Associate Professor T, who is also NUS Department of Materials Science and Engineering,

“When surgeons perform minimally-invasive surgery such as laparoscopic or robotic surgery, we can control the jaws of the grippers, but we are unable to feel what the end-effectors are gripping. Therefore, surgeons have to rely on our sense of sight and years of experience to make decisions about important information that our sense of touch could otherwise provide,” said Dr Kan, Consultant, Department of General Surgery at National University Hospital Hung Leng said. , Ng Teng Fong General Hospital and NUS Yong Lu Lin School of Medicine,

Dr Kan, who is not involved in the research project, elaborated, “The haptic or tactile feedback provided by smart pressure sensors has the potential to revolutionize the field of minimally-invasive surgery. For example, information about whether the tissue being grasped is hard, tough, or soft provides an additional and important source of information to assist surgeons in making judicious decisions during surgery. Ultimately, these intra-operative benefits have the potential to translate into improved surgical and patient outcomes.

Additionally, EAIR presents an opportunity to improve the process of monitoring intracranial pressure – the pressure within the skull that can affect brain health. Similarly, by offering a minimally invasive solution, the technology could transform patient experiences in managing brain-related conditions, ranging from severe headache to potential brain damage.

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