I intend to use a microcontroller with integrated capacitive touch functionality for this application. The touch pad is about 2 cm in diameter, and the required sensing distance is approximately 10 cm when a palm approaches. Which brand of microcontrollers with capacitive touch features provides more sensitive sensing performance?
Bro, trying to achieve 10cm gesture sensing with a 2cm PAD? That’s physically a bit far-fetched. The capacitance change caused by a finger at a 10cm distance is extremely small (likely just at the aF level), and your 2cm PAD simply can’t emit an edge electric field that far. Even if you crank the sensitivity to the max, any change in ambient temperature, humidity, or a high-power device passing nearby will cause false triggers.
If you must use an MCU’s built-in solution, go for Cypress (now acquired by Infineon) PSoC series without hesitation. Their CapSense (especially the 5th-gen CSX mutual capacitance technology) is widely recognized as the industry leader, and with Driven Shield technology, it offers the strongest interference resistance. Alternatively, take a look at TI’s CapTIvate, which has great signal-to-noise ratio. But no matter which you choose, I’d suggest making your sensing antenna (PAD) larger, or switching to a loop antenna design—the 2cm size is really too tight.
Take my advice: for over 10 cm of touchless sensing distance, don’t use capacitive solutions—the interference issues during mass production will bury you! Especially when you need to pass EMC tests like ESD or EFT, having such high sensitivity is a nightmare.
Suggested alternatives:
- Use active infrared (IR) receiver/transmitter pairs, which cost just a few cents, or a single photodiode proximity switch IC.
- If your budget allows, go straight for ST’s VL53L0X basic ToF (Time-of-Flight) sensor. Distance measurement is extremely precise—you set it to exactly 10 cm, and it stays at 10 cm, unaffected by temperature, humidity, or metallic materials.
10cm proximity sensing (Proximity Sensor) can be done by many domestic manufacturers, so there’s no need to use expensive foreign chips.
Recommend checking out CHIPSEA (Shenzhen Chipsea Technologies Co., Ltd.). They started with high-precision ADC and touch solutions, and their CS32 series touch-enabled models offer high sensitivity, with dedicated proximity sensing configurations available in the manufacturer’s algorithm library. Also consider Holtek, a leader in home appliance touch solutions. While their BS81 series are dedicated ICs, their touch-enabled MCUs are also very reliable.
It’s best to get a development board from a distributor and have the manufacturer’s FAE help you adjust the threshold. For such short-range sensing, the algorithm and PCB layout are more important than the chip itself.
Frankly, achieving 10cm detection with a 2cm PAD poses significant physical challenges.
Typically, SAR Sensors (proximity sensors) used in smartphones have reached sensitivity levels in the aF (attofarad) range. On a 20mm \times 20mm antenna, the maximum detection distance is usually limited to 30mm \sim 50mm. For 10cm detection, the signal-to-noise ratio (SNR) would be extremely poor.
If you still want to pursue a capacitive sensing solution, here’s some advice:
- Chip Selection: Don’t rely on the touch functionality built into standard MCUs; go straight for dedicated SAR Sensors.
- Foreign options: Semtech sets the standard with the most stable algorithms; ABOV from South Korea is widely used in wearable products.
- Domestic options: Goodix, Awinic, and Tax Rate Chip, which are all part of the supply chain for major smartphone/wearable manufacturers, offer solid performance.
- Pain Points to Note: At such extreme sensitivity levels, temperature drift becomes the biggest enemy, often causing false triggers.
That said, for a distance of 10cm, IR (infrared) or ToF sensor solutions are far more reliable than capacitive sensing, with better cost and development cycle control.