What Are the Types of Spo2 Sensors? A Complete Analysis

A SpO2 sensor is a critical part of a pulse oximeter, a medical device used to measure the level of oxygen saturation in the blood. Picking the correct SpO2 sensor is essential for your patient’s comfort and accurate results. So what are the types of SpO2 sensors available?

There are four common types of SpO2 sensors: neonatal, infant, pediatric, and adult SpO2 sensors. Consider age, weight, and application site when choosing a SpO2 sensor.

What Is a SpO2 Sensor, and How Does It Work?

A SpO2 sensor is a detector for blood oxygen concentration. The pulse oximeter sensor measures the amount of hemoglobin attached to oxygen molecules.

Pulse oximetry uses the Beer-Lambert Law of light absorption. A SpO2 sensor consists of red and infrared LEDs and photo sensors or photodiodes. The LED emits light at fixed wavelengths, and the photosensor measures the amount of light transmitted through a pulsatile arterial bed.

The absorption of LED light by oxygenated and deoxygenated hemoglobin differs. So a photodiode on the opposite side of the light tracks changes in light absorption by pulsations in arterial blood flow. Finally, a microprocessor calculates the oxygen saturation before the monitor displays the result.

Which Sensor Is Used for SpO2?

Pulse oximetry sensors use red and infrared LEDs to determine oxygen saturation in your body. There are two technologies used during pulse oximetry: transmissive and reflective.

  • Transmissive technology: This is the most common of the two. Here, the sensor is positioned on a slender body part like an infant’s foot, finger, or earlobe. The red and infrared light is then passed through the application site to a photodetector.

  • Reflective technology: Here, the transmitter and receiver are on the same side, unlike in the transmissive method. You can place these sensors on other body parts, such as the forehead, chest, or foot, even if it’s not slender.

Types of SpO2 Sensors

The accuracy of the SpO2 readings will depend on the type of pulse oximeter probe you use, meaning it’s crucial to choose a suitable one. Here are the most common sensor types:

  • Neonatal SpO2 sensors: In addition to the saturation number, neonatal SpO2 sensors can check sinus arrhythmia.

  • Infant SpO2 sensors: They check the oxygen saturation levels in infants and plethysmographic waveforms.

  • Pediatric SpO2 sensors: Pediatric SpO2 sensors check oxygen and heart rate for neonates, babies, or children. Place this sensor on the toes or fingers. The child’s weight can help determine if the sensor is suitable for use on the patient.

  • Adult SpO2 sensors: They are used in adults to measure arterial blood and pulse rate.

The sensors are categorized into the following groups:

  • Disposable SpO2 sensors: Perfect for single-patient use, these sensors are widely used in emergency rooms, operating rooms, ICU, NICU, or hospital wards where patients need continuous monitoring. They help prevent cross-contamination and provide comfort to patients.

  • Reusable SpO2 sensors: These can be used multiple times or on different patients. They are easy to clean and disinfect, hence reducing cross-contamination.

Some new generation pulse oximeters have sensors capable of connecting to a smartphone through Bluetooth. The sensor measures blood saturation and pulse rate and transfers the data wirelessly to your phone.

What to Consider When Choosing a SpO2 Sensor

Besides considering the type of pulse oximeters, here are other things to keep in mind when choosing a SpO2 sensor.

Age and Weight

Age and weight are essential when choosing Spo2 sensors because their design depends on the patient using them. There are SpO2 sensors for neonates, infants, children, and adults.

Also, sensors depend on weight. So before picking one, check the weight specifications to know if the person using the oximeter falls under the weight bracket.

Application Site

Knowing where to place the sensor is also crucial for getting accurate results. The SpO2 sensor design depends on the application site, such as the foot, finger, wrist, toe, forehead, and ear. It’s good to note that it’s possible to use a sensor in the wrong place, which can give incorrect readings. So know where you want to use the sensor before picking one.

Monitoring Duration

Each patient has a different need. Some require short monitoring, while others need continuous monitoring. So remember to factor in your patient’s comfortability if you’re monitoring them for extended periods.

Patients Mobility

Motion can highly affect the accuracy of SpO2 readings. That’s why it’s crucial to consider patient mobility when picking a sensor. Depending on your patient’s mobility, you can choose low, limited, general, or high-activity SpO2 sensors.


Before purchasing a sensor, check whether it’s FDA approved. A certified Spo2 sensor means that it meets quality standards and assures accuracy. Also, accredited devices show that experts have validated the technology it uses.

What Are the Different Types of Oximeters?

There are several different types of pulse oximeters, which are all designed to measure arterial oxygen saturation (SpO2) and pulse rate.

Fingertip Oximeters

Fingertip oximeter is also known as a portable pulse oximeter. It’s a small device with a rectangular shape clipped on the finger, and the result is shown on a display screen.

Finger oximeters are battery-operated and are mainly for home use. Also, they are ideal for medical settings during spot-checking. Moreover, they are the most efficient and affordable oximeters on the market today.

Handheld Oximeters

Handheld oximeters are perfect for spot-checking and continuous monitoring as they provide accurate results. It’s common in hospitals and other medical facilities. The probe is clipped to your finger and has a cable connected to a monitor that shows the results.

Tabletop Oximeters

A tabletop oximeter is a larger version of a handheld oximeter. It is more expensive and needs to be placed on a flat surface, hence its name. It’s perfect for hospitals, clinics, and subacute facilities for spot-checking and continuous monitoring.

Fetal Pulse Oximeters

They are used during fetal pulse oximetry for monitoring oxygen saturation for the well-being of a fetus during labor. The probe rests on the fetus’s head in the uterus or the vagina.

Initially, fetal oximetry was believed to reduce the number of cesarean sections for non-reassuring fetal status, which was associated with the use of the conventional cardiotocographic (CTG) only. However, studies came to rule out this.

Wrist Pulse Oximeter

This is the best oximeter you can buy if your doctor wants to monitor your oxygen levels even when sleeping. It uses wireless technology, so it does not need to be connected to a monitor. The wrist oximeter’s monitor has a wristwatch design. It also has a small wire attached to the probe and clips on the finger.

The FDA categorizes pulse oximeters into two groups:

  • Prescription oximeters: These are primarily used in hospital settings, although you can use them in homes under prescription. They are FDA certified, meaning they give a more accurate reading. However, prescription oximeters may be more expensive than OTC oximeters.

  • Over-the-counter (OTC) oximeters: These are the most commonly used oximeters for home use. You can get one directly from the drugstore or online, even without a doctor’s prescription.

OTC oximeters may have a phone app to help display and store the readings. However, it’s good to note that the FDA does not recommend using OTC oximeters for medical purposes since they have not reviewed them.

Which Is the Best SpO2 Oximeter?

The market is full of SpO2 oximeters, and deciding which is the best can be daunting. Here are some of the best oximeters you can find online:

Masimo MightySat Fingertip Pulse Oximeter

Masimo is one of the topmost brands for pulse oximeters. The MightySat oximeter uses Signal Extraction Technology (SET), which guarantees accuracy even during movement, when it’s cold, and even in brightly lit environments. It measures breaths per minute (RRp), pulse rate, Pleth Variability, and perfusion Index. It is FDA approved and most commonly used in hospital settings.

MightySat oximeter comes with a Masimo Personal Health App so you can track your respiratory status using your smartphone. Its only downside is its cost. This oximeter goes for $299, which is pricey, but it has incredible features, so you get value for your money.

CONTEC CMS50M Pulse Oximeter

CONTEC CMS50M Pulse Oximeter is portable, light, and compact. It checks oxygen saturation and pulse rate. You can use it in healthcare facilities, homes, oxygen bars, fitness, and physical training rooms.

CONTEC CMS50M Pulse Oximeter has an accuracy rate of 70% to 100% (±2%). It’s easy to use and very affordable. Unfortunately, it comes without batteries. Also, it’s good to note that these oximeters are not medical devices; they’re only for use in sports and aviation.

Oxiline Pulse 9 Pro

The Oxiline Pulse 9 Pro is an affordable device that measures SpO2, perfusion Index (PI), and pulse rate. It also shows the plethysmograph waveform in real-time.

This oximeter is relatively priced and FDA-approved, making it rate among the best SpO2 oximeters. In addition, online Pulse 9 Pro offers a one-year money-back guarantee.

Facelake FL400 Pulse Oximeter

A Facelake FL400 oximeter is a lightweight and compact device that measures and displays your blood oxygen level and pulse rate. Its design is for all ages, but it may show mixed results if the fingers are too small. However, this product is not FDA approved, so it’s not a medical device.

Take Away

Pulse oximetry is crucial for any patient care. The SpO2 sensor you choose for your oximeter will depend on your patient’s age, weight, and application site. SpO2 sensors can either be disposable or reusable, so choose depending on the patient or your needs.

Seek immediate medical advice if you notice your SpO2 levels are below 95% or below 90% if you have chronic lung disease. It’s good to consult your physician before making a pulse oximeter purchase to get their advice on which model is best for your needs.