An ultrasensitive, all-optical nanoscale force detector discovered by Columbia University engineers, which uses light to measure force, could bridge the gap between conventional piconewton and micronewton force detectors, making it the most sensitive force response sensor with the largest dynamic range ever realized.
Made from specially engineered luminescent nanocrystals that change intensity or color (or both) when any mechanical force is applied, the breakthrough force detector that researchers describe as a “tour de force” can potentially disrupt several cutting-edge industries.
“We expect our discovery will revolutionize the sensitivities and dynamic range achievable with optical force sensors and will immediately disrupt technologies in areas from robotics to cellular biophysics and medicine to space travel,” explained project leader Jim Schuck, associate professor of mechanical engineering at Columbia, in a statement.
All-Optical Force Detector 100 Times More Sensitive
The nanocrystals used in the new force detector are based on the idea of photon-avalanching, which was first discovered by Shuck’s Columbia Engineering team. In photon-avalanching, a single photon injected into specific nanoparticles sets off a chain reaction that ultimately results in the emission of several photons.
To test the sensitivity of selected photon-avalanching nanoparticles (ANPs), the research team, which was joined by scientists from The Molecular Foundry at the Lawrence Berkeley National Laboratory (Berkley Lab), “tapped” several different particles with an atomic force microscope that can deliver pressures in the reactive range of these particles. The resulting changes in color and light in their crystals revealed they were even more force-sensitive than the team had projected.
“We discovered this almost by accident,” Schuck said. “We suspected these nanoparticles were sensitive to force, so we measured their emission while tapping on them. And they turned out to be way more sensitive than anticipated!”
The effect was so pronounced that Schuck says that his team initially didn’t believe it, noting that “we thought the tip may be having a different effect.” However, when study co-author and fellow Columbia Engineering department staffer Natalie Fardian-Melamed performed a series of control measurements, Shuck said they found that the unexpectedly sensitive nanoparticle response “was all due to this extreme force sensitivity.”
Further testing revealed that the nanoparticles had 100 times better force sensitivity than exiting optical sensors that utilize rare earth ions to generate light. The team’s specialized force detector also showed an operational range spanning four orders in force magnitude. According to the research team, this range is “10-100 times larger than any previous optical nanosensor.”
Transforming the Paradigm of Sensing
Given the ultrasensitive nature of this ultrasensitive force detector, the Columbia team says it can operate in varied environments, but under conditions currently available, sensors cannot operate. The fact that the detection of force is revealed by the emission of light, which can be sensed from a distance without any wires, the team believes it can have immediate applications in several technology-dependent industries.
“What makes these force sensors unique – apart from their unparalleled multiscale sensing capabilities – is that they operate with benign, biocompatible, and deeply penetrating infrared light,” Fardian-Melamed says. “This allows one to peer deep into various technological and physiological systems and monitor their health from afar.”
Potential applications highlighted by the Columbia team include monitoring developing embryos, tracking cellular migration, especially when monitoring disease, and even monitoring sensitive electronic components for battery failure. The team also believes their force detector can aid in very sensitive nanoelectromechanical systems (NEMS) “which the physical motion of a nanometer-scale structure is controlled by an electronic circuit, or vice versa.”
“Enabling the early detection of malfunction or failure in these systems, these sensors will have a profound impact on fields ranging from human health to energy and sustainability,” Fardian-Melamed said.
“We are excited to be part of these discoveries that transform the paradigm of sensing, allowing one to sensitively and dynamically map critical changes in forces and pressures in real-world environments that are currently unreachable with today’s technologies.,” Shuck added.
The study “Infrared nanosensors of piconewton to micronewton forces” is published in Nature.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.