Complete Guide of Biomedical Sensors Updated
Introduction
Biobiomedical sensors are conversion devices that convert physiological information of the human body into electrical information that has a definite functional relationship with it. The information it picks up is the physiological information of the human body, and its output is often expressed in electrical signals by sensors.
1 Working Principle
In modern medicine, biomedical sensors actually replace the doctor’s sensory organs and play an extended role. It has become a key technology that restricts the development of high-level advanced medical equipment. The important technological foundation of the information society. There are two types of human physiological information: electrical information and non-electrical information. In terms of distribution, there are internal (such as blood pressure and other types of pressure), body surface (such as various types of bioelectricity such as ECG) and the external (such as infrared, biomagnetism, etc.).
2 Biobiomedical Sensor Characteristics
As an important branch of sensors, the design and application of biomedical sensors must consider the influence of human factors, such as the particularity and complexity of biological signals, and the biocompatibility, reliability and safety of biobiomedical sensors.
1) The sensor itself has good technical performance, such as sensitivity, linearity, hysteresis, repeatability, frequency response range, signal-to-noise ratio, temperature drift, zero drift, sensitivity drift, etc.
2) The shape and structure of the sensor should be adapted to the anatomical structure of the tested part, and the damage to the tested tissue should be small.
3) The sensor has a small impact on the measured object. In other words, it will not bring a burden to physiological activities, and does not interfere with normal physiological functions of humans.
4) The sensor must have enough firmness so that it will not fall off or be damaged when use it.
5) The sensor and the human body must have sufficient electrical insulation to ensure the safety.
6) When the sensor enters the human body, it can adapt to the chemical action in the biological body. For example, it is compatible with the chemical composition in the biological body, is not easy to be corroded, has no adverse irritation to the human body, and is non-toxic.
7) If the sensor enters the blood or is buried in the body for a long time, it should not cause blood problem.
8) The sensor should be simple to operate, easy to maintain, and easy to sterilize in structure.
3 Classifications
3.1 According to the Working Principle
1) Chemical sensor
Use the principle of chemical reaction to convert chemical composition and concentration into electrical signals.
2) Biological sensor
Use the selective identification of biologically active substances to determine biochemical substances.
3) Physical sensor
Take advantage of physical changes in materials.
4) Bioelectric electrode sensor
Use the body's various bioelectricity (cardioelectricity, brain electricity, myoelectricity, neuron discharge, etc.).
3.2 According to the Type of Detection
Displacement sensor, flow sensor, temperature sensor, speed sensor, pressure sensor, etc. For pressure sensors, including metal strain gauge pressure sensors, semiconductor pressure sensors, capacitive pressure sensors, etc. For temperature sensors, including thermistors, thermocouples, PN junction temperature sensors and other sensors that can detect temperature.
3.3 According to Human Senses
1) Vision Sensor
Including various optical sensors and other sensors that can replace vision functions.
2) Hearing Sensor
Including various pickups, piezoelectric sensors, capacitive sensors and other sensors that can replace auditory functions.
3) Olfactory Sensor
Include various gas-sensitive sensors, and sensors that can replace the olfactory function.
This classification method is conducive to the development of bionic sensors. In addition to the widely used sensor classification methods, there are also multiple classification standards based on sensor materials, structures, energy conversion fractions, etc., all with their own advantages and limitations.
4 Biomedical Sensors Functions
(1) Provide diagnostic information, such as heart sounds, blood pressure, pulse, blood flow, respiration, body temperature and other information for clinical diagnosis and medical research.
(2) Monitoring: Long-term continuous measurement of certain parameters, monitoring whether these parameters are within the specified range, in order to check the patient's recovery process, and take actions when abnormalities occur. For example, after a heart operation, it is necessary to monitor changes in a series of parameters such as body temperature, pulse, arterial pressure, venous pressure, respiration, and electrocardiogram of a patient.
(3) Human body control: Use the detected parameters to control the physiological process of the human body. For example, an automatic respirator uses a sensor to detect the patient’s breathing signal to control the movement of the respirator to synchronize the breathing of the human. Another example is the electronic prosthesis, which uses the measured electromyographic signal to control the movement of the human prosthesis. What’s more, have the blood flow and blood pressure control of cardiopulmonary bypass.
(4) Clinical tests: In addition to collecting information directly from the human body, diagnostic information is often obtained from various body fluids (blood, urine, saliva, etc.) samples. This type of information is called biochemical test information. It is obtained by using chemical sensors and biosensors, and is an indispensable basis for diagnosing various diseases.
5 Biomedical Sensors Applications
5.1 Patient Lift Chair
Electric chair lifts can provide a safe and efficient way to transfer patients from one place to another, helping to ensure the safety of patients. These basic equipment can greatly reduce the burden on nursing staff when using other transfer methods to keep on patient safety and comfort. These chairs have a lightweight and portable design and are suitable for many medical care environments. For example, modern versions of these chairs also incorporate load cells to further enhance their performance. The weighing sensor designed to measure the weight of the patient can be connected to an alarm, and when the load exceeds the safety upper limit, an alarm will be issued to the health staff immediately.
5.2 Sports Rehabilitation Machine
Usually used in physiotherapy, these machines are usually used to exercise the patient's muscles as part of the therapy to restore the patient's motor skills and mobility after the patient has suffered a stroke or sports injury. With our advanced technology, modern rehabilitation machines can now provide intelligent sensing capabilities to detect the movement of patients. By integrating load cells, we are now able to provide the controller with the real-time feedback needed to predict the patient's next movement. The intelligent resistance control can increase or decrease the resistance of the exercise machine according to the force measured from the patient's actions, thereby promoting the patient's muscle growth in the most suitable way. The load cell can also be used to measure the weight of the patient, so that the rehabilitation machine can estimate the height of the patient, and pre-position the handle of the machine at the correct level in an efficient manner.
5.3 Artificial Prosthesis
After a long period of development, artificial prostheses have been improved in many aspects, from the comfort of materials to the integration of electromyographic control using electrical signals generated by the wearer’s own muscles, to the fact that artificial prostheses are extremely realistic in appearance and have the same skin texture. Even match pigments and details such as hair level, nails and texture.
With the integration of advanced sensors into artificial prostheses, further improvements can be brought about. They are aimed at enhancing the natural movement of artificial prostheses for arms and legs, and providing the correct amount of strength assistance during exercise. Our solutions include weighing sensors and custom force sensors that can be built into artificial prostheses. These sensors can measure the pressure of each patient's movement, thereby automatically changing the resistance of the artificial prosthesis. This feature allows patients to adapt and perform daily tasks in a more natural way.
5.4 Infusion Pump
It is the most commonly used and basic tool in the medical environment and can achieve flow rates from 0.01 mL/hr to 999 mL/hr. Our customized solutions help reduce errors and achieve the goal of providing high-quality and safe patient care. And the solution can provide reliable feedback to the infusion pump to ensure continuous and accurate drug delivery, and the liquid is delivered to the patient in a timely and accurate manner, reducing the supervision workload of medical staff.
5.5 Baby Incubator
Rest and reducing bacterial exposure are key factors for newborn care. Therefore, the baby incubator is designed to protect weak babies by providing a safe and stable environment. The load cell is incorporated into the incubator to achieve accurate real-time weight measurement without affecting the baby's rest or exposing the baby to the external environment.
5.6 Infrared Thermometer
It is a kind of devices with non-contact temperature sensor, its sensitive element and the measured object are not in contact with each other, also known as non-contact temperature measuring instrument. This kind of instrument can be used to measure the surface temperature of moving objects, small targets and objects with small heat capacity or rapid temperature changes (transient), and it can also be used to measure the temperature distribution of the certain field. In today's outbreak of COVID-19, physical contact has been minimized and the spread of bacteria and viruses has been reduced greatly.
6 Biomedical Sensors Development
Among them, the research and development of the sensor itself has two branches. One is related to the basic research of the sensor, that is, the research on the new technology and new principles required by the sensor.
In recent years, the development of medical sensor products has become more and more popular, and the productization of sensor technology in the field of medical equipment products has become increasingly popular. Innovative medical products such as wearables, artificial intelligence AI, surgical robots, etc. are emerging in an endless stream. Modern medical sensor technology has got rid of the technical shortcomings of traditional biomedical sensors such as large size and poor performance, and has formed new development directions such as intelligence, miniaturization, multi-parameter, remote control, and non-invasive detection.
The development of biomedical sensors is already one of the key technologies restricting the development of high-end and advanced medical equipment, and it is also one of the main driving forces to promote the development of medicine.
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