Biomedical Sensors: Classifications, Applications, and Challenges
Table of Contents
What is a Sensor?
A sensor is basically a device that helps to detect a condition through the generation of electrical, optical, mechanical, chemical signal. On the other hand, a transducer is a device that takes part in the sensor and helps in the conversion of energy from one form to another. For several devices and measurement systems, sensors are the critical components.
A sensor is a tiny and intelligent device that helps to measure several physical variables such as temperature, pressure, velocity, flow rate, gas, humidity, electric fields, light, and so on. For this reason, sensors have significant applications in medical devices such as digital thermometers, digital blood pressure meters, respiration pulse oximeters, spirometers, and location sensors based on magnetic fields.
Classification of Sensors:
Sensors can be classified in different ways. For instance, depending on the functions, types, applications, and placements, there are different types of sensors.
On the basis of function, sensors can be classified as electrochemical, optical, mechanical, bio, thermal, semiconductor, magnetic, and so on. Based on the type, there are different types of sensors such as blood oxygen sensors, blood glucose sensors, temperature sensors, image sensors, ECG sensors, inertial sensors, motion sensors, pressure sensors, etc. On the basis of application area, there are monitoring, diagnostics, medical therapeutics, wellness, fitness, and imaging sensors. Depending on the sensor placement, sensors can be classified as wearable sensors, strip sensors, implantable sensors, ingestible sensors, and invasive/non-invasive sensors.
Biomedical Sensors:
In biotechnology and medicine, biomedical sensors mainly serve the purpose of detecting specific physical, biological, or chemical processes in our body through transmitting or reporting the monitored data. The systems that are used to process clinical samples, sensors are the essential components of those systems, for example, to prepare the lab-on-a-chip devices.
The use of miniaturized biomedical sensors is significantly increasing for the measurement of blood pressure, cerebrospinal fluid pressure, muscle displacement, core body temperature, bone growth velocity, and blood flow. As the adaptation of home healthcare by the people is increasing day by day, the need for medical instruments that consist of biomedical sensors is growing tremendously. The design of sensors employs miniature coils as the most essential part of the device. However, producing such tiny coils requires overcoming several technical challenges. Micro-coils should also be manufactured in large quantities maintaining high standards.
Applications of Biomedical Sensors:
A miniaturized micro-coil can serve several purposes. In order to prepare the navigation components that are the key elements in disposable catheters, micro-coils are necessary. For instance, to perform cardiac ablation, micro-coils play an essential role in cardiovascular catheters.
Micro-coils have substantial applications in several areas such as-
- In the case of miniature implants, micro-coils help to log data to and from the implant and control and monitor the transfer of data,
- Implants require energy to operate and activate the systems and micro-coils help to provide energy for battery charging or electrical charge input,
- In several medical treatments such as heat treatments, electromagnetic radiation-based treatments, and radiating energy for RF treatments, micro-coils are essential.
- In order to conduct in-vivo magnetic navigation through engaging an external or local magnetic field, micro-coils are necessary.
There are also several areas of new possibilities that the micro-coils produce for medical devices. However, in order to fulfill these purposes, the manufacturers should conduct the mass production of the micro-coils maintaining high quality at a reasonable price.
Challenges:
Manufacturing such tiny micro-coils involve several challenges due to physical size constraints and environmental conditions. The wire for the manufacturing of micro-coils should have a diameter of 59 AWG or 9 microns. Handling these ultra-fine wires that are 5 to 10 times smaller than a human hair is not an easy task and requires customized and specialized machinery. On the other hand, the final products need to meet strict tolerance requirements and overcome a long list of environmental and physical constraints.
Many manufacturers have developed micro-machining technologies that are able to prepare micro-coils that have more than 1000 windings, yet the size of the head of a pin. An essential part of the micro-coil winding process is the connection of ultra-fine wires. In order to join two ultra-fine wires of similar or different diameters and materials, thermo-compression binding technology has been proven a lot more effective than the traditional methods of soldering and welding methods. Many manufacturers use this technology for its tight tolerances at very high temperatures.
