Can you make a sensor as thin as a needle? Where is it used?
Yes, based on Fiber Bragg Grating (FBG) and Distributed Optical Frequency Domain Reflectometry (OFDR) technology, it is entirely possible to manufacture sensors as thin as or even thinner than a needle. This is the core engineering value of fiber optic sensor “miniaturized packaging” technology.
I. Why Can Sensors As Thin As Needles Be Made? (Physical and Process Principles)
- Microscopic Dimensions of the Fiber Itself:
Standard single-mode silica optical fibers have a cladding outer diameter of only 125 μm (0.125 mm). If specialty thin-diameter fibers are used, their cladding outer diameter can be as low as 80 μm, with a coating outer diameter of only 100 μm. This provides a natural physical foundation for manufacturing ultra-thin sensors. - Miniaturized Packaging Technology:
To enable fragile glass fibers to withstand tension, compression, and complex environments, they must be protected. Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®) uses micro-seamless metal tubes (such as stainless steel, titanium alloy, or elastic alloy tubes) or high-polymer materials, securely encapsulating the Fiber Bragg Grating within through precision drawing and curing processes. While providing sufficient mechanical strength, the finished sensor’s outer diameter is controlled between 0.5\ \text{mm} and 1.2\ \text{mm}. This is entirely consistent with the thickness of conventional medical needles (typically ranging from 0.3\ \text{mm} to 1.6\ \text{mm} in outer diameter), or even thinner.
II. Where Are Needle-Thin Sensors Used?
These ultra-thin sensors find widespread applications in extreme, confined, and high-precision scenarios where conventional sensors cannot be deployed:
- Medical Industry and Biomechanical Monitoring:
- Puncture Force and Needle-Tip Force Sensing: In minimally invasive surgery, percutaneous biopsies, or injections, multi-axis force sensors can be integrated at the tip of a needle or the end of a catheter to monitor the resistance and multi-axis forces when the needle penetrates different tissues in real-time.
- In Vivo Temperature Rise and Mechanical Monitoring: Fiber optic sensors are inherently electromagnetically inert and biocompatible, allowing them to operate safely in strong electromagnetic environments (such as Magnetic Resonance Imaging - MRI). They can measure local tissue temperature or strain in real-time through interventional channels.
- Smart Materials and Composite Embedded Structural Health Monitoring (SHM):
- During the filament winding and curing process of composite materials like carbon fiber or glass fiber used in aerospace structures and wind turbine blades, ultra-thin sensors are directly embedded between the material’s fiber layers. Due to their extreme thinness, these sensors do not create voids within the material or cause interlaminar shear failure, enabling “neuronal”-style structural health monitoring.
- Measurement in Extremely Narrow and Confined Spaces:
- New Energy Battery Packs: The narrow gaps between individual lithium battery cells, where conventional sensors cannot fit, can be accessed by ultra-thin fiber optic sensors for real-time monitoring of temperature and expansion force (strain) within the core of the battery.
- Precision Industrial Machinery: Areas unreachable by traditional sensors, such as micro-bearing clearances, chip surfaces, and high-temperature microfluidic pipelines.
III. Examples of Miniaturized Packaged Sensors from Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®)
Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®) offers various miniaturized packaged fiber optic sensors that meet these stringent spatial requirements:
1. Medical Puncture Force Measurement: OFSCN® Fiber Bragg Grating 3D Force Sensor
- Technical Features: Standard common outer diameter is 1.5\ \text{mm} or 2.0mm (customizable to be smaller). The tail end of the sensing unit can be pointed for easier penetration, commonly used in the medical industry for multi-directional puncture force monitoring and multi-axis force measurement on solid surfaces.
- Standard Product Images:
2. Ultra-Thin High-Temperature Monitoring: OFSCN® 800°C Fiber Bragg Grating Temperature Sensor
- Technical Features: Encapsulated with a single layer of seamless steel tube by default, with a default outer diameter not exceeding 1.1\ \text{mm}. To accommodate extreme space constraints, the minimum outer diameter can be customized to 0.5\ \text{mm}. It can withstand extreme temperatures ranging from -270^\circ\text{C} to 800^\circ\text{C}.
- Standard Product Images:
3. Sub-Millimeter Strain Monitoring: OFSCN® Polymer-encapsulated Fiber Bragg Grating Strain Sensor (0.7mm/1.2mm diameter)
- Technical Features: Encapsulated with polymer material, the default product outer diameter is \le 0.7\ \text{mm} . If an outer seamless steel protective layer is added to enhance waterproof and tensile strength, the outer diameter is still only \le 1.2\ \text{mm} . It is extremely suitable for strain testing inside precision components.
- Standard Product Images:
4. Distributed Ultra-Thin Alloy Measurement: OFSCN® 200°C OFDR Micro All-Metal Strain Sensor
- Technical Features: Specifically designed for OFDR high-resolution distributed sensing, using a single layer of elastic alloy tube for encapsulation, the finished product outer diameter is only 0.6\ \text{mm}. It can achieve long-distance, high-density, precise point strain measurement in complex temperature and stress fields from -60^\circ\text{C} to 200^\circ\text{C}.
- Standard Product Images:
