MAX30100 Pulse Oximeter Heart Rate Sensor Module Compatible for Arduino 1.8V ? 5.5V is its operating voltages. The heart sensor module brand is MAX30100. The Digital is its Output type. the working principle of this sensor is Biosensor. this is a pressure-sensitive and force-sensitive sensor. The polymer is its material texture. I2C is Its interface type. 18.8 x 14.4 3 mm is the dimensions of the Heart sensor module. Heart Sensor weight is 1.2g.

MQ-9 MQ9 Carbon Monoxide Gas Alarm Combustible Sensor Module For Arduino Suitable for home or factory gas leakage monitoring devices. Have better sensitivity to CARBON MONOXIDE, METHANE, LIQUEFIED PETROLEUM GAS. High quality dual-panel design, with power indicator and TTL signal output instructions. DO switching signal (TTL) output and AO analog signal output. TTL output valid signal is low. (When the output low signal is on, it can be directly connected micro-controller or relay module.) Analog output voltage: the higher concentration, the higher voltage. Four screw holes, easy positioning. Long life and stability, quick response and resume. Input voltage: DC 5?0.2V Power: 150mA DO output: TTL digital 0 and 1 (0.1 and 5V) AO output: 0.1-0.3V (relatively clean), the highest concentration voltage is about 4V. Dimensions: 32(L) * 20(W) * 22(H) mm AO ? analog signal output