Unable to do otg communication with the app

I have created a non invasive thermometer using microcontroller-Nodemcu, Proximity Sensor, ADPS 9960, Temperature Sensor - MLX 90614, I am interfacing this with the app which I have created using flutter.

I am trying to print the value of the temperature measured on the app through usb communication. I have gone through all the steps and have followed it. But on measuring the temperature random value are printed. Could someone pls guide where I am going wrong or what might be the issue.

Arduino ide Code:
#include <Wire.h>
#include <SparkFun_APDS9960.h>
#include <Adafruit_MLX90614.h>

SparkFun_APDS9960 apds = SparkFun_APDS9960();
uint8_t proximity_data = 0;
Adafruit_MLX90614 mlx = Adafruit_MLX90614();

void setup() {

mlx.begin();
apds.init();
apds.enableProximitySensor(false);

Serial.begin(9600);

}

void loop() {
String temperature = “”;
apds.readProximity(proximity_data);

if (proximity_data == 255 && mlx.readObjectTempF() < 100) {

temperature = String(mlx.readObjectTempC(), 1);
Serial.print(" Body Temperature:");
Serial.println(mlx.readObjectTempC());
delay(1000);

}

if (proximity_data == 255 && mlx.readObjectTempF() > 100) {

temperature = String(mlx.readObjectTempC(), 1);
Serial.print(" Body Temperature:");
Serial.println(mlx.readObjectTempC());
Serial.print(" CRITICAL \n");
 delay(1000);

}
}