Wireless contact force sensing and localization
Inventors
Gupta, Agrim • Girerd, Cedric • Dunna, Manideep • Morimoto, Tania • Bharadia, Dinesh • Subbaraman, Raghav • Zhang, Qiming
Assignees
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Publication Number
US-12644784-B2
Publication Date
2026-06-02
Expiration Date
Abstract
A wireless force sensor includes a flexible structure supported opposing a rigid structure with a gap between the flexible structure and the rigid structure. Contact traces on opposing surfaces of the flexible structure and the rigid structure form transmission lines. The contract traces are aligned to contact when a force is applied the flexible structure to cause contact between the traces on the opposing surfaces. Radio-frequency switches modulate a reflected signal from the transmission lines. An antenna receives an interrogation signal transmits the reflected signal.
Core Innovation
A wireless force sensor is provided for robotics and minimally invasive surgery and includes a flexible structure supported opposite a rigid structure with a gap between the flexible structure and the rigid structure. Contact traces are located on opposing surfaces of the flexible structure and the rigid structure so that the contact traces form transmission lines, and the contact traces are aligned such that when a force is applied, the flexible structure causes contact between the traces on the opposing surfaces.
The wireless force sensor further includes radio-frequency switches configured to modulate a reflected signal from the transmission lines, and an antenna configured to receive an interrogation signal and to receive or transmit the reflected signal. The force application creates force-dependent contact edges that short the transmission lines, producing backscatter phase changes. Wideband phase measurements across subcarriers enable decoding of force magnitude and application location from the reflected signal phase behavior.
A bilayer flexible beam suspended over a rigid base with a gap maps a force location to shorting points at contact edges, such that different force locations produce different transmission-line short patterns. RF switching modulates the backscattered reflected signal, and the sensor uses RF interrogation to obtain phase changes for decoding of force magnitude and force location. Batteryless operation based on RF energy harvesting and ultra-low power operation are described, with sub-3 GHz operation and experimental results indicating force accuracy and contact-location accuracy.
Claims Coverage
The independent claim covers a wireless force sensor architecture with a flexible-gap contact-trace transmission-line structure, radio-frequency switch modulation of a reflected signal, and an antenna for interrogation and reflected-signal reception. Two additional inventive features are described by dependent claims, including mechanical bilayer structure and communication features for backscattered phase communication.
Gap-supported flexible structure with opposing contact traces forming transmission lines
A flexible structure supported opposing a rigid structure with a gap between the flexible structure and the rigid structure; contact traces on opposing surfaces of the flexible structure and the rigid structure, the contact traces forming transmission lines; the contact traces being aligned to contact when a force is applied to the flexible structure to cause contact between the traces on the opposing surfaces.
Radio-frequency switches modulating a reflected signal from the transmission lines
Radio-frequency switches to modulate a reflected signal from the transmission lines.
Antenna receiving interrogation signal and receiving the reflected signal
An antenna to receive an interrogation signal and to transmit the reflected signal.
Bilayer flexible structure with stiffer and softer layers positioned relative to the rigid structure
The wireless force sensor uses a flexible structure formed as a bilayer with a stiffer layer and a softer layer positioned closer to the rigid structure.
Clock source and backscattered phase communication to a wireless reader
The wireless force sensor includes a clock source and RF switches configured to communicate backscattered phases to a wireless reader.
Across the independent claim, the core coverage centers on a gap-supported flexible-versus-rigid structure whose opposing contact traces form transmission lines that are shorted by applied force, with RF switches modulating a reflected signal that is received or transmitted via an antenna. Dependent claim refinements specify bilayer mechanical structure and add clock-enabled backscattered phase communication.
Stated Advantages
Batteryless operation via RF energy harvesting.
Ultra-low power operation.
Sub-3 GHz operation bandwidth.
Experimental force accuracy of about 0.3 N.
Experimental contact-location accuracy of about 0.6 mm.
Demonstrated power consumption on the order of less than about 1 μW.
Documented Applications
Robotics.
Minimally invasive surgery.
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