An Accessible and Parent-Specific Haptic Feedback Baby Monitor

I don’t have any kids myself, but I hear that parenting is hard. One of the most common complaints among new parents — and the reason I am choosing to remain childfree — is a lack of sleep. For decades, parents have used baby monitors to keep tabs on their babies sleeping in their nurseries. But those baby monitors only output sound (and video on nicer models), which means they aren’t useful for deaf parents and also that they wake both parents. To solve those two problems, soon-to-be parent Guy Dupont built an accessible haptic feedback baby monitor.

Dupont started with a cheap VTech baby monitor that only transmits sound. Like all similar baby monitors, this model has a microphone unit that goes in the nursery next to the baby and a speaker unit that parents can keep in their room or carry with them. The microphone unit connects wirelessly to the speaker unit. Dupont’s upgrade converts the speaker unit’s sound output to vibratory haptic feedback on a bracelet. Because it is haptic feedback instead of sound, it will only wake or notify the parent wearing the bracelet.

That’s perfect for families in which only one parent is responsible for the baby on a given night and the other parent needs sleep. It is also great for people who can’t hear well. As a bonus, the strength of the haptic feedback vibration is proportional to the volume of the baby’s cries and mimics their sound patterns. In theory, that should help parents recognize the kind of sound that their baby is making so that they can act accordingly.

Instead of converting the actual audio signal to a vibration signal, Dupont’s setup measures sound levels by monitoring the speaker unit’s LEDs. This model has five LEDs and the number of lit LEDs corresponds to volume. A Seeed Studio XIAO nRF52840 microcontroller development board checks to see how many LEDs are on, then sets the vibration strength to match. The XIAO connects to a motor driver board that controls a small vibratory motor — the kind found in adult toys that lead to the creation of babies in the first place. An aux cable connects the motor driver to the vibratory motor, which attaches to a thick hair band worn on the parent’s wrist.

The XIAO nRF52840 has Bluetooth 5.0 support, which is how users configure the settings (such as vibration strength). Using any generic Bluetooth app, they can connect to the XIAO on their smartphone and enter commands to program settings. The Bluetooth connection would also allow for additional features in the future. For now, this setup should help the Duponts get more sleep than the average parents.