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WEBENCH® Tools/LMT70: LMT70

Anas Shalyan
Prodigy 25 points
Part Number: LMT70

Tool/software: WEBENCH® Design Tools

Hi, I am making a device which is measure human feet temperature by puting LMT70 in the insole shoes. However, i am using Thin Flexible Circuit Board Materials with a low modulus polyimide with 40 LMT70  on the top of the PCB. I have tried my circuit and  the sensors worked well.

1- I have read in the data sheet that the measurement for LMT70 should be from the button of the sensors is that the best option?   

2- What material should I use to make the best connectivity between the LMT70 and human skin in order that i am using Flexible Circuit polyimide ? 

3- can I put any material on the top of LMT70 which will not effect the temperature measurement in order that the sensors will be in insole of shoe?

Best regards    

  • 0
    TI__Expert 5695 points
    Hi Anas,
    Thanks for considering the LMT70 device for your interesting application. Did you mean 4 or 40 devices?

    Did you have a chance to review the reference design for wearable applications using same device? If not I highly recommend it to review it. You may find interesting recommendations there. Please use the link below:
    www.ti.com/.../tida-00824

    Also you can review the application note listed below where the subject of temp sensors in wereables is treated in depth.
    www.ti.com/.../snia021

    If you still have some questions after reviewer gets this material please let us know.

    Regards,
    Jose.
  • 0 in reply to Jose Arteaga4
    Prodigy 25 points

    Hi, I have 20 sensors in each feet so in total are 40. I have seen the first link you have sent to me. TIDA-00824 Test Results link In figure 3 they have been used remote PCB to measure the skin temperature by using holes in each pin of sensor to be able to have the reading from the bottom of PCB if i am right? .  My project is to measure  skin temperature by implement  20 sensors in  the insole shoe and it will masseur a specific area on the feet . The difference in my project is that i am using Thin Flexible Circuit Board Materials with a low modulus polyimide, and i have to put a material  on the bottom of the sensor to give me an accurate measurement in order that it is not possible for me to have holes under the sensor pin as I saw in Link  TIDA-00824 Test Results figure 3. Which kind of material can I use?. The second problem that i will have peruser on the top and bottom  of the sensors in order that the people are going to walk.  What can i do with that is there any thing as well i can put on the top of sensor to product it and at the same time still get  accurate measurement. I can send you a picture of the PCB in case you couldn't understand me well. 

    Kind regards 

    Anas 

  • 0 in reply to Anas Shalyan
    TI__Mastermind 37370 points
    Hi Anas,

    Thank you for reaching to us. In figure 3 of the TI Design, the thermal dominant path is through its metal ball. This will allow the LMT70 to sense the temperature changes quickly. In order to get the heat transfers from the bottom to the top of the LMT70, The mini PCB was designed with a small plane on the bottom through a via.

    Please provide me the diagram or the picture that you are referring to. If you don't want to reveal your design on the forum, I will send you private session shortly.

    Aaron