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 1MΩ 
 Temperature sensors 

Maximum sensitivity NTC thermistor for ultra-low current applications and high-precision temperature measurement.

 Maximum precision
+/- 0,2°K

 Minimum temperature
-50°C

 Maximum temperature
+150°C

 Minimum dimensions
2 x 10

Response time

Medium

 Drift

Low

 Self-warming
Low

Price
Low

What is a NTC 1MΩ sensor ?Operating principleTechnical SpecificationsWiring ConfigurationSelf-warmingApplication areas

What is a NTC 1MΩ sensor ?

The NTC 1 MΩ is a very high impedance thermistor that offers almost zero power consumption.

Its use is intended for autonomous measurement systems where even the slightest dissipation matters — for example, in long-term environmental sensors, IoT modules, or passive precision instruments.

Operating principle

Its resistance follows the typical exponential law of NTC:

R(T) = R₂₅ × e^{β (1/T - 1/T₂₅)}

where:

  • R₂₅ = 1 000 000 Ω 
  • β ≈ 3950 K
  • T in kelvins

The reading is done via numerical linearization (Steinhart–Hart equation) to ensure accuracy.

Technical Specifications

Parameter
 Typical value

Nominal resistance (25 °C)

 1 000 000 Ω ±1 %
Constant β 3950 K

Sensitive material

Metallic oxide (Mn, Ni, Co)

Type of case Epoxy / glass

Maximum measurement current

0,005 mA

Response time

0.3 to 1 s

Linearity

Exponential (non-linear)

Operating temperature

−50 → +150 °C

Lifetime

100,000 thermal cycles

Wiring Configuration

The NTC 1 MΩ is configured as a voltage divider, connected to a high-impedance analog input (≥10 MΩ).

It is often used with 24-bit ADC converters to detect minute variations.

 +Vcc
   │
  [Rfixe]
   │────► ADC (µC)
  [NTC 1MΩ]
   │
  GND

Self-warming

With a measurement current of less than 5 µA, the dissipation is negligible: no alteration of the actual measured temperature.

Application areas

🔋 Ultra-low power autonomous sensors (IoT, BLE, LoRa)

🌡️ Ambient and isolated object thermal monitoring

🩺 Sensitive medical instrumentation

🧠 Long-term measurement systems without recalibration

⚙️ Passive and calibrated electronic equipment


Should I choose a 1MΩ sensor ?

Strengths points

  • 🔋 Measurement current almost nonexistent
         → The NTC 1 MΩ consumes less than 5 µA: perfect for battery-powered devices or maintenance-free passive sensors.
  • 🧠 Ideal for high impedance differential measurements
         → Used in instrumentation amplifiers or high Z inputs, it ensures exceptional electrical isolation.
  • 🌍 Compatible with isolated environments
         → Its very high resistance allows for reliable measurements even in areas with strong electromagnetic noise or with long transmission cables.
1MΩ Sensors

Weaknesses points

  • 🐢 Slow response in rapid variation
    → The very low measurement current induces a longer stabilization delay, which is not well suited for sudden temperature changes.
  • 🧮 Demanding lecture on the electronics side
    → → Requires a 24-bit ADC or an input >10 MΩ to avoid charge errors and ensure accuracy.
  • 🌡️ Limited dynamic usage range
    → High temperatures (>120 °C) lead to a significant decrease in sensitivity, which limits its use to ambient applications.

Useful information

Here is some useful information regarding the 1MΩ sensors.

(NTC 1 MΩ at 25 °C, constant β = 3950 K)

Temperature (°C) Resistance (Ω) Temperature (°C) Resistance (Ω)
−50 24 940 000 60 292 000
−40 15 800 000 70 220 000
−30 10 170 000 80 169 000
−20 6 708 000 90 130 000
−10 4 484 000 100 101 000
0 3 046 000 110 78 000
10 2 095 000 120 63 000
20 1 474 000 130 50 000
25 1 000 000 140 40 000
30 686 000 150 32 000
40 476 000 160 26 000
50 336 000 170 21 000

💡 Between 0 °C and 100 °C, the resistance is divided by about 30 — typical of an NTC β ≈ 3950 K.

Class / Tolerance
 Tolerance at 25 °C (R25)
 Max error on T° (−40 → +125 °C)
 Typical usage
±1 % ±10 000 Ω ±0,2 K Precision thermal studies
±2 % ±20 000 Ω ±0,4 K Calibration Systems
±3 % ±30 000 Ω ±0,6 K Environmental monitoring
±5 % ±50 000 Ω ±1 K Long battery life devices / IoT
🔹 Glass or ceramic encapsulated versions are preferred for their excellent moisture stability and mechanical resistance.

Complete equation:

1/T = A + B · ln(R) + C · [ln(R)]³

Typical coefficients for NTC 1MΩ (β = 3950 K):

  • A = 1.4051 × 10⁻³
  • B = 2.369 × 10⁻⁴
  • C = 1.019 × 10⁻⁷


🔹 Example 1: Temperature from R

R = 686,000 Ω

ln(686000) = 13,44

1/T = 1,4051e−3 + 2,369e−4 (13,44) + 1,019e−7 (13,44)³ = 3,05e−3

T = 1 / 3,05e−3 = 328 K = 55 °C

✅ Measured temperature ≈ 55 °C


🔹 Example 2: Resistance from T

T = 80 °C = 353.15 K

R = R₂₅ · e^(β(1/T − 1/T₂₅))

R = 1000000 · e^(3950 × (1/353,15 − 1/298,15)) = 169000 Ω

✅ Expected resistance: ≈ 169 kΩ

The NTC 1 MΩ is designed to be integrated into an ultra high impedance voltage divider, where the measurement current remains in the order of a few microamperes.

🔹 Typical components

Component
 Function
NTC 1 MΩ Temperature sensor
R fixed (1 MΩ)
 Reference resistance
Microcontroller / ADC (24 bits)
 Analog lecture
100 nF capacitor
 Filtering
Power Supply 3.3 / 5 V
 Stable and clean tension
🔹 Functional diagram (ASCII)
  +3.3V / +5V
       │
     [Rfixe]
       │────► ADC (microcontroller input)
     [NTC 1MΩ]
       │
      GND
💡 Its very high resistance ensures negligible consumption, making it ideal for long-lasting sensors or systems without continuous power supply.

 We integrate any sensor into any probe 

Smooth tube probe

 Smooth tube 

Waterproof probe

 Waterproof

Bayonet probe

 Bayonet

Slot probe

 Slot

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 Atmosphere

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Termal block

Stick-in probe

Stick-in

Thread probe

Thread

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Contact

Jacketed probe

Jacketed

PCBA Design

PCBA design

Winding probe

Winding

More than 1,000,000 probes delivered in 2025

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