/Temptress

Miniature medical grade NFC temperature sensor

Creative Commons Zero v1.0 UniversalCC0-1.0

LitAF Temptress

This device is a miniaturised NFC tag that enables the reading of temperature from two TMP112 sensors as well as a LED that can be enabled or disabled. The NFC interface is provided by an NTAG5 NFC to I2C bridge chip. Top Side PCB Render Bot Side PCB Render

Coil Design

  • Target Frequency: 13.56MHz
  • Target Q Factor: 50
  • Chip Capacitance: 15pf
  • External Capacitance: ~62pf
  • Target Coil Inductance: 1.76uH
  • Coil Shape: "Rectangular"
  • Coil Height: 25mm
  • Coil Width: 5mm
  • Coil Turns: 8
  • Coil Trace Width: 0.1mm
  • Coil Trace Spacing: 0.1mm
  • Coil Copper Thickness: 2oz

Bill Of Materials

  • 1 x NTAG5 (Link or Boost)
  • 2 x TMP117
  • 3 x Tuning Cap (C1-3)
  • 3 x Smoothing Cap (C4-C6)
  • 1 x Current Limiting Resistor
  • 1 x IN-S124AR LED

Schematic

Schematic

Note

This was designed as a demo project for a class that I ran. The design has not been tested and was made in a very short period of time. Whilst it should work, it is far from the ideal design for this sort of device.

Manufacturing Info

This design was created with the PCBWay 2 layer flex PCB manufacturing specifications in mind. If you order this using the CAM files provided, you need to order with 2oz copper.