Sensors
Objective:
The objective of the sensors group is to use pressure and temperature sensors to collect the data needed to autonomously regulate the system. The temperature sensor will measure temperature of the body at the area of cooling that will be applied by the thermoelectric coolers (TEC). The temperature sensor will be connected to the Lilly-Pad which is the brains of the operation. The data that that is obtained by the Lilly-Pad through the temperature sensor, will be the data used to regulate the output current and voltage of the TEC. By altering the power output to the TEC will regulate how much the TEC cools the body. In the ideal design the pressure sensor will act in the same way as the temperature sensor. It will measure the compression of the TEC to the skin and upon this data it will regulate the power output of the TEC just as the temperature sensor does.


Specific
The specific problem that we are addressing is to find sensors that can be placed on the body that small, to achieve the idea of less bulk for the whole system. The sensors need to be able to read temperatures between 32oC to about 43oC because this is the range of temperatures we will be working with. The pressure sensor needs to be flat and be able to flex and bend with the shape of the body.

Temperature Sensor on Prototype #1
Description:
This is the latest DS18B20 1-Wire digital temperature sensor from Maxim IC. Reports degrees C with 9 to 12-bit precision, -55C to 125C (+/-0.5C). Each sensor has a unique 64-Bit Serial number etched into it - allows for a huge number of sensors to be used on one data bus. This is a wonderful part that is the corner stone of many data-logging and temperature control projects.
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One Wire Digital Temperature Sensor - DS18B20

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Features:
  • Unique 1-Wire® interface requires only one port pin for communication
  • Each device has a unique 64-bit serial code stored in an onboard ROM
  • Multidrop capability simplifies distributed temperature sensing applications
  • Requires no external components
  • Can be powered from data line. Power supply range is 3.0V to 5.5V
  • Measures temperatures from –55°C to +125°C (–67°F to +257°F)
  • ±0.5°C accuracy from –10°C to +85°C
  • Thermometer resolution is user-selectable from 9 to 12 bits
  • Converts temperature to 12-bit digital word in 750ms (max.)
  • User-definable nonvolatile (NV) alarm settings
  • Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition)
  • Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system


One Wire Digital Temperature Sensor - DS18B20

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This is the configuration setup of the one wire digital temp sesor that the programing group willneed to use to make the proper connections to the contrpler and the power input



Temperature Sensor on Prototype #2

Description:
Melexis' MLX90614ESF-BAA is an infrared thermometer designed for non-contact temperature sensing. An internal 17-bit ADC and a powerful DSP contribute to the MLX90614's high accuracy and resolution. It has a huge number of applications including body temperature measurment and movement detection.

The MLX90614 provides two methods of output: PWM and SMBus (i.e. TWI, I2C). The 10-bit PWM output provides a resolution of 0.14°C, while the TWI interface has a resolution of 0.02°C. The MLX90614 is factory calibrated in wide temperature ranges: -40 to 85°C for the ambient temperature and -70 to 382.2°C for the object temperature. The measured value is the average temperature of all objects in the Field Of View of the sensor. The MLX90614 offers a standard accuracy of 0.5°C around room temperatures.

This devices comes in an industry standard TO-39 package. We're carrying the 3V version of this sensor.

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Infrared Thermometer - MLX90614

Features:
  • Small size, low cost
  • Easy to integrate
  • Factory calibrated in wide temperature range:
    • -40 to +85°C for sensor temperature
    • -70 to +380°C for object temperature
  • SMBus compatible digital interface
  • Customizable PWM output for continuous reading
  • High accuracy of 0.5°C over wide temperature range (0 to +50°C for both Ta and To)
  • Measurement resolution of 0.02°C
  • Single and dual zone versions
  • Simple adaptation for 8 to 16V applications
  • Power saving mode
  • Different package options for applications and measurements versatility
  • Automotive grade


Describe
Temperature sensors are a critical part of the total design of the system they are used to regulate the temperature of the body through controlling the output of power in the TEC. Temperature sensors are placed all around the system to measure room temperature, heat sink/ hot side of TEC temperature, cold side of TEC temperature, and the temperature at direct contact of the skin and idealy core body temperature. In the prototype number one we will use the one wire digital temperature sensors to measure all of these areas of our system. In the second prototype we will use the Infrared Thermometer to measure the direct contact and core body temperatures because they will work more accuratly if there isn't direct skin contact all the time. The infrared sensor does not need direct skin/object contact to measure the temperature. It is also has high accuracy as the one wire digital temperature sensor wchich is of 0.5°C.
complete documentation including:

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This is the configuration setup of the Infrared Temp Sensor