• It is a component widely used in the automatic control industry for detecting, controlling, and noncontact switching. When the proximity switch is close to some target object, it will send out a control signal.
• As it is a capacitive type proximity switch, its detecting object target is not limited to an only conductor, but also liquid and even powder things, like plastic, water, glass, oil, etc.
• It's widely used in machines, paper making, the light industry for limiting stations, orientation taking count, speeding trials, etc.
• Integrated circuit proximity switch which is composed of oscillator and shaping amplifier oscillator start-up after induction head switches the last alternating magnetic field.
• This series of proximity switches for high-frequency oscillation with no contact, no pressure, no spark, quickly issued a detection signal.
• This series of proximity switches are widely used in modern industry, machinery, metallurgy, transportation, electric power, military, textile, chemical, mining, scientific research departments of machine tools, and industrial automatic production lines.
• This switch includes a high-frequency oscillating circuit, detection circuit, amplifier circuit, trigger circuit, and output circuit.

MQ-2: Sensitive to methane, butane, LPG, smoke (for flammable gases)
MQ-3: Alcohol, ethanol, smoke
MQ-4: Methane, CNG gas
MQ-5: Natural gases, LPG
MQ-6: LPG, butane gas
MQ-7: carbon monoxide
MQ-8: Hydrogen gas
MQ-9: Carbon monoxides, flammable gases
MQ-135: Air quality, benzone, alcohol, smoke

• Detect AC current up to 5A
• Current limit can be set through precision VR
• Voltage range from DC 5V
• LED Indicator for output result

• Diffuse reflective type
• Light source: Infrared
• Sensing range: 3cm to 80cm (depends on obstacle surface)
• Input voltage: 5VDC
• Current consumption: 100mA
• NPN output
• Dimension: 1.8cm (D) x 4.3cm (L)
• Cable length: 45cm

• Operating Voltage: 3.3 ~ 5.5 VDC
• Output Voltage: 0 ~ 3.0VDC
• Operating Current: 5mA
• Interface: PH2.0-3P
• Weight: 15g

• 3 pins (GND[-], VCC[+] and Out)
• DHT11 humidity and temperature sensor with appropriate pull-up resistors
• 2.5mA max current use during conversion (while requesting data)
• Good for 20-80% humidity readings with 5% accuracy
• Good for 0-50°C temperature readings ±2°C accuracy
• No more than 1 Hz sampling rate (once every second)
• Only use 1 I/O pins on the Arduino

• Full range temperature compensated 
• Relative humidity and temperature measurement
• Calibrated digital signal 
• Outstanding long-term stability 
• Extra components not needed
• Long transmission distance 
• Low power consumption 
• Low cost

• Smaller footprint, lower power consumption, lower noise measurements, lower RMS noise.
• Higher resolutions for pressure and temperature, higher measuring rate.
• Easy-to-use Crowtail Compatible Interface.
• Can be used as an altimeter with accuracy of ±1 meter.

• Adopt IO trigger through supplying at least 10us sequence of high level signal
• The module automatically send eight 40khz square wave and automatically detect whether receive the returning pulse signal
• If there is signals returning, through outputting high level and the time of high level continuing is the time of that from the ultrasonic transmitting to receiving
• Detection distance: 2cm~450cm
• High precision: Up to 3mm

• Operating voltage: 3.3 – 5V
• Current: 4mA
• Digital Pulse Output Corresponding to Heart Rate.
• Indicator LED

• Accept wide range of volatge, DC 6V to 36V
• Easy installation with threaded screw body
• Industry standard NPN output
• 1mm detection distance 
• Object detected indication 

• Sensor Type: Infrared
• Voltage: 3.3 - 5VDC
• Current: 45mA (5V)
• Detection Distance: 2 - 30cm (adjustable with potentiometer)
• Size: 32x14mm
• Weight: 3g

• Working voltage of 3.3 V to 5 V
• Can be adjust the detection distance through the potentiometer knob
• Widely used in robot obstacle avoidance, obstacle avoidance car, line count, and so on many occasions
• Light weigh and compact design
• Easy to connect to Arduino

• On-board MAX30100 IC integrate optical biosensor including two LEDs, a photodetector, optimized optics, and low-noise AFE
• Measures absorbance of pulsing blood
• Programmable sample rate and LED current for power savings increases battery life for wearable devices
• I2C interface
• Ultra low power operation increases battery life for wearable devices
• It is an integrated pulse oximetry and heart rate monitor sensor solution
• Applications: Wearable Devices, Fitness Assistant Device and Medical Monitoring Devices

• Fitness and sports heart rate monitoring
• Portable ECG
• Remote health monitor
• Game peripheral equipment
• Bioelectricity signal collection