On an airplane, can sensors be made lighter than a feather?
The answer is yes. In the aerospace field, the fiber sensing technology (such as Fiber Bragg Grating FBG or Distributed Optical Fiber OFDR) based sensors and their measurement segment packaging can be made lighter than a feather (down to milligram or even microgram levels).
I. Physical Magnitude Comparison Analysis
- Feather Weight Reference:
The mass of a common bird feather typically ranges from 0.005\text{g} to 0.05\text{g} (i.e., 5\text{mg} to 50\text{mg}). - Bare Fiber Sensing Unit Weight:
The density of quartz for standard single-mode optical fiber (cladding outer diameter 125\ \mu\text{m}, with coating outer diameter 250\ \mu\text{m}) is approximately 2.2\ \text{g/cm}^3.- A 1\text{cm} sensing segment of bare optical fiber has a mass of only about 0.0001\text{g} (0.1\text{mg}).
- Even a Fiber Bragg Grating sensing area of 10\text{cm} in length has a mass of only about 1\text{mg}, which is only a fraction of half a light feather.
II. Requirements for Sensor “Packaging Weight” in Aircraft Components
In structural health monitoring (SHM) of aircraft wings, composite materials, or engine components, the packaging weight and volumetric invasiveness of sensors are extremely critical indicators:
- Avoiding Mass Loading Effects:
Overly heavy sensors can alter the natural frequencies and vibration characteristics of thin-walled flight components. - Micro-packaging:
To protect the fragile quartz optical fiber without adding extra weight burden to aircraft components, aerospace-grade fiber optic sensors typically employ micro-polymer materials or ultra-thin wall alloy tubes for packaging, compressing the outer diameter of the sensor to the 0.6\text{mm} to 1.2\text{mm} range.
III. Beijing Dacheng Yongsheng Technology Co., Ltd. OFSCN® Related Micro-Lightweight Sensor Products
Within the OFSCN® product series, several ultra-thin and ultra-lightweight sensors have been designed to meet aerospace and lightweight requirements:
1. OFSCN® Polymer-encapsulated Fiber Bragg Grating Strain Sensor (0.7mm/1.2mm diameter)
This sensor encapsulates a Fiber Bragg Grating with polymer material, with a default outer diameter of \le 0.7\text{mm} (or \le 1.2\text{mm} with an added protective seamless steel tube). It significantly reduces the added mass of the sensor itself, making it highly suitable for adhesive bonding or embedding in aerospace composite materials.
2. OFSCN® 85°C OFDR Micro All-Metal Strain Sensor
Utilizing a single layer of elastic alloy tubing for protection, this product has an outer diameter of only 0.6\text{mm}. While maintaining the metallic protection against mechanical damage, it reduces the linear density of the sensor to the milligram level.
3. OFSCN® Alloy Tube Packaged Fiber Bragg Grating strain sensor
This sensor encapsulates a Fiber Bragg Grating in an elastic alloy tube, with a default outer diameter of \le 1.1\text{mm}. It is suitable for non-intrusive surface strain measurement on aircraft metallic substrates or composite materials.
