Our Products & Services

Fiber Sensing Technologies

CEL strain gauge technicians understand the importance of precise gauge placement and orientation. Great care is taken in surface preparation, gauge installation, and egress routing, to ensure successful test data under critical conditions. We apply a variety of gauge types including foil, free filament, semiconductor, and fiber optic, in many configurations and sizes.

  • Available in many different configurations
  • Sensors may be externally bonded to new or existing structures (e.g., steel members)
  • Sensors may be embedded in new construction (e.g., concrete and steel re-bar)
  • Measure movements down to the picometer range – Sensors provide continuous and valuable data on strain and tension in steel members (open or in concrete), temperature, curing, stability, wind loads, and effects of seismic activity or nearby excavations/erosion
  • The same sensors used during construction may be integrated and used as part of a permanent structural health monitoring system
  • Continuous monitoring facilitates predictive analysis of structural integrity and bridge health as a function of loads, age and/or later additional construction in surrounding area
fbg gauge III

FiberStrike FBG Switch

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A state-of-the-art solution for monitoring the status of virtually any access point. With the scalable distances allowed by fiber optics, our interlock switches can be networked across a wide area, while utilizing existing standard communication fiber networks. Additional advantages include the passive nature of each sensor, with no need for electrical power at any sensor location, immunity to environmental problems that can plague electrically based sensors, and the ability to network virtually any number of sensors over nonconductive optical fiber into a single monitoring system that can be tens of kilometers distant from the sensing location.

FiberStrike LCM-620 switches are designed for intrusion detection at access portals such as manholes and hatchways. These switches also are well suited for high EMI/RFI industrial environments requiring many open-close sensing points, or any other applications where knowledge of many go/no-go contact states in a network is required.

fbg switches

FBG Brainy Bolt

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Brainy Bolt sensors allow continuous measurement of elongation and tension on a structural fastener in any location.

  • Sensor may be integrated into virtually any bolt, rivet, stud or screw having a body diameter of 12.7mm / 0.50” or greater
  • Integration of sensor in fastener has no effect on ultimate tensile strength of fastener
  • 20-30 sensors may be multiplexed on a single optical fiber, facilitating ease of installation

Fiber optics are inherently immune to electromagnetic and radio frequency interference, lightning and corrosion. Brainy Bolts contain no electronic components, require no electrical power, and emit no signals, making them an excellent choice for long term, real-time structural monitoring applications in both benign and hazardous environments.

brainy bolt fbg sensor

Principle of Operation

A Brainy Bolt contains a fiber sensor known as a Fiber Bragg Grating (FBG). Light is fed into the fiber, and the FBG reflects light of one given wavelength back to an optical interrogator. If the tension on the optical fiber changes, the reflected wavelength of light correspondingly changes; any change is detected by the optical interrogator and then converted into a tension measurement. All Brainy Bolts also provide individual temperature compensation capability using the same internal fiber and optical interrogation methodology.

  • Brainy Bolt inserts are delivered with the internal FBG slightly pre-tensioned and pre-calibrated to reflect at a specific wavelength.
  • FBGs can be individually tuned, each to a unique wavelength, so each sensor may be given its own address; this allows multiple FBGs, each individually addressable, to be arrayed on a single fiber.
  • Multiple FBGs on one fiber allows many Brainy Bolts or other fiber sensors to be networked with minimal fiber optic cabling.
  • Brainy Bolts are equipped with a preinstalled armored optical fiber pigtail that is spliced into single-mode 1550nm fiber leading to the optical interrogator; the pigtail is available in various lengths.
  • Many Brainy Bolts can be simultaneously monitored in real-time by the optical interrogator.
  • The optical interrogator may be located at distances up to 25+ km from sensors.

Modification of Fastener to Accept Brainy Bolt

A structural fastener in which tension is to be monitored is modified to accept a Brainy Bolt insert by boring and threading the fastener according to specific machining dimensions. An example of modification dimensions to accept a Brainy Bolt insert having a body length of 1.25 inch is shown in Figure 1. Modification dimensions to accept Brainy Bolts having other body lengths will be provided by CEL-ATG as required. A fastener modified to accept a Brainy Bolt should have a body diameter no less than 0.5” and a shank length such that the bottom of the Brainy Bolt insert terminates above the threads of the fastener. Figure 1. Dimensions of fastener modification to accept Brainy Bolt insert. (Generic bolt shown.) Engineering analyses performed by CEL show that this modification has no effect on the ultimate tensile strength of a structural fastener of any alloy that has a diameter of at least 0.5 inch (although stiffness is reduced); there is a small effect on shear strength, but this effect becomes negligible in fasteners of larger diameter. It is the responsibility of the fastener certifying authority to determine the proper size fastener for the application and to determine that the fastener retains adequate strength for its application after modification. CEL can modify fasteners to the certifying authority’s specifications to accept Brainy Bolt inserts. CEL also can provide Brainy Bolt inserts and instructions for fastener modification to the integrator.

Installation of Brainy Bolt in Modified Fastener

Brainy Bolt inserts monitor the tensile load on a fastener by measuring the elongation of that fastener, but Brainy Bolt inserts are neither designed nor intended to bear any of the tensile load on the fastener. Accordingly, proper torque on a Brainy Bolt insert is essential when integrating it into a structural fastener. The head of a Brainy Bolt is a “tamper-resistant” configuration, and a special tool, part number LCM-255 available from CEL, is required to properly engage the head on the insert. Only this tool, and a ¼” drive torque wrench adjustable in inch-pounds, should be used to install a Brainy Bolt insert. No other tool(s) should be used for this purpose. CEL will specify the proper torque value to use for any installation. From small industrial to large structural applications, Brainy Bolt inserts can be integrated into many fastener types to enable real-time measurements and structural monitoring not previously possible. Brainy Bolts are one example of the many innovative FiberStrike® sensors offered by Cleveland Electric Laboratories to help you solve your monitoring problems. We invite your inquiries.

FBG Pedestrian Platform

LCM 940 Pedestrian Sensing Platforms Brochure

An effective solution for detecting the presence of pedestrians in specific locations. LCM-940 sensing platforms connect to remote monitoring equipment via non-conductive optical fiber. Benefitting from the very long working distances allowed by fiber optics, sensing platforms may be located tens of kilometers distant from the monitoring equipment. Existing standard communications fiber infrastructures may be leveraged to connect a network of platforms, and multiple platforms may be leveraged to connect a network of platforms, and multiple platforms may be multiplexed over a single optical fiber while remaining individually addressable, simplifying the logistics and reducing the costs of installation.

Example applications for FiberStrike LCM-940 platforms include sensing of pedestrian presence at railway/subway/mass-transit platforms, movements along defined paths, and intrusion detection along hallways or in front of doorways or hatches that access secure areas.

fbg pedestrian platform fiber optic sensor systems security intrusion detection platform with fiber optics

FBG Linear & Rotary Position Sensor

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