Difference between Max30100 and Max30102 Sensor?

As many people have many doubts regarding which sensor to use, which pulse oximeter would be more accurate, how will the pins be connected, and what is the difference between these heart rate sensors is, so here in this blog, all the doubts will get cleared one by another.

Max30100

The MAX30100 is a heart rate monitoring sensor along with a pulse oximeter. To detect pulse oximetry and heart rate signals, it incorporates two LEDs, a photodetector, improved optics, and low-noise analog signal processing. The MAX30100 runs on 1.8V and 3.3V power sources, and it may be turned down by software with very little standby current, allowing the power supply to be connected at all times.

Pin Configuration of MAX30100 pulse oximeter sensor:

MAX30100 is a seven pin sensor module with an enabled I2C communication protocol to interact with the microcontroller.

Working of MAX30100 Pulse Oximeter and Heart-Rate Sensor

The device has two LEDs, one of which emits red light and the other of which emits infrared light. The wavelength of red light is 660nm, whereas the wavelength of infrared light is 940nm. Only infrared light is required to determine pulse rate. The amounts of oxygen in the blood are measured using both red and infrared light.
When the heart pumps blood, the amount of oxygenated blood in the blood increases as a result of having more blood. The amount of oxygenated blood reduces when the heart relaxes. The pulse rate is calculated by measuring the time between the increase and decrease of oxygenated blood.
Deoxygenated blood absorbs red light and passes more infrared light, whereas oxygenated blood absorbs red light and passes more infrared light. The light is absorbed by the oxygenated blood, while the rest is reflected through the finger and falls onto the detector, which is then processed.

Functional Block and the Circuit Diagram of MAX30100 Module

The photodiode result is transferred to the analog-to-digital converter, from which digital data will be sent to the digital data register through a filter. The data from the register may be gathered and transferred to the microcontroller using the I2C communication protocol.

MAX30102

MAX30102 is a sensor that combines a pulse oximeter and a heart rate monitor. It's an optical sensor that measures the absorbance of pulsating blood through a photodetector after emitting two wavelengths of light from two LEDs - a red and an infrared one. This particular LED colour combination is designed to allow data to be read with the tip of one's finger.  It is fully configurable through software registers and the digital output data is stored in a 16-deep FIFO within the device. It has an I2C digital interface to communicate with a host microcontroller. 

Pin Configuration of MAX30102 Oximeter Module:

MAX30102 is a 7 pin sensor module with an enabled I2C communication protocol to interact with the microcontroller.

The MAX30102 is fully adjustable through software registers, and the digital output data can be stored in a 32-deep FIFO within the IC. The FIFO allows the MAX30102 to be connected to a microcontroller or processor on a shared bus, where the data is not being read continuously from the MAX30102’s registers.

SpO2 Subsystem

 The SpO2 subsystem of the MAX30102 contains ambient light cancellation (ALC), a continuous-time sigma-delta ADC, and a proprietary discrete-time filter. The ALC has an internal Track/Hold circuit to cancel ambient light and increase the effective dynamic range. The SpO2 ADC has programmable full-scale ranges from 2µA to 16µA. The ALC can cancel up to 200µA of ambient current. The internal ADC is a continuous-time oversampling sigma-delta converter with an 18-bit resolution. The ADC sampling rate is 10.24MHz. The ADC output data rate can be programmed from 50sps (samples per second) to 3200sps. 

Temperature Sensor 

The MAX30102 has an on-chip temperature sensor for calibrating the temperature dependence of the SpO2 subsystem. The temperature sensor has an inherent resolution of 0.0625°C. The device output data is relatively insensitive to the wavelength of the IR LED, where the Red LED’s wavelength is critical to correct interpretation of the data. A SpO2 algorithm used with the MAX30102 output signal can compensate for the associated SpO2 error with ambient temperature changes.

 LED Driver

 The MAX30102 integrates Red and IR LED drivers to modulate LED pulses for SpO2 and HR measurements. The LED current can be programmed from 0 to 50mA with proper supply voltage. The LED pulse width can be programmed from 69µs to 411µs to allow the algorithm to optimize SpO2 and HR accuracy and power consumption based on use cases.

How does Pulse Oximeter Works?

As we know oxygen enters the lungs and then it gets is passed on into blood. The blood carries oxygen to the various organs in our body. The main way oxygen is carried in our blood is by means of haemoglobin. During a pulse oximetry reading, a small clamp-like device is placed on a finger, earlobe, or toe.

Small beams of light pass through the blood in the finger, measuring the amount of oxygen. It does this by measuring changes in light absorption in oxygenated or deoxygenated blood. Oxygenated blood absorbs more infrared light and passes more red light while deoxygenated blood absorbs red light and passes more infrared light. The light emitted gets absorbed by the oxygenated blood and the rest of the light is reflected through the finger and falls over the detector whose output data is then processed( I2C communication protocol) and read through a microcontroller.

MAX30100 vs MAX30102

32-bit FIFO vs. 16-bit FIFO - the MAX30102 has more storage for data that has yet to be passed to the microcontroller, allowing for quicker data transmission.

18-bit vs 14-bit ADC resolution - the MAX30102 is more sensitive to changes in IR receiver voltage

69 us-114 us vs 200 us-1.6 ms LED pulse width - the MAX30102 has a narrower LED pulse width, resulting in lower power consumption

These things justify the slight price increase on the MAX30102 than MAX30100.

PCB Difference 

The MAX30102 and MAX30100 module come in a green-coloured board with almost the same components mounted on the PCB but with a slight difference in MAX30102 and MAX30100 which is the main IC of the modules.

SPECIFICATIONS

FOR PURCHASING THESE SENSORS(Click on the name of the sensor):

Max30100

MAX30102