11 Replies Latest reply on Oct 28, 2018 11:09 PM by dougw

    Sensing Baby Kicks

    ipv1

      I have made a belt for sensing when our unborn child kicks from the inside. This is useful for tracking activity and health of the baby. In my current configuration, I am using a piezoelctric sensor strip but there are a few issues.

      1. The strip is small and cannot cover a large surface area.
      2. It will not discriminate between kicks and movement caused by the mother herself.


      I was able to condition the signals and send them over BTLE but the sensor is an issue.

      Can anyone suggest? Thanks.

        • Re: Sensing Baby Kicks
          dougw

          Interesting sensor challenge.

          Assuming the kicks generate a different spectrum of accelerations than a movement, perhaps an accelerometer or microphone would provide an easier signal to analyze. (Low-cost Piezo sensors generally have a resonant frequency that make spectral analysis difficult)

          Another method might be to use a different sensor to detect when mother is moving and ignore the kick sensor at these times. This sensor would be mounted closer to her muscles and further from the baby. It could even use EMG sensors (electromyography).

          Doug

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          • Re: Sensing Baby Kicks
            Jan Cumps

            Wow, that's a tough one. I'd almost think you'd need to pick up subsonic sounds and use DSP to recognise relevant signals. But I wouldn't be able to do that myself .

             

            Maybe a broad belly belt of wearable conductive/resistive cloth where you can measure sudden changes in resistance when the little foot hits the belly?

            3 of 3 people found this helpful
            • Re: Sensing Baby Kicks
              ipv1

              Interesting theories. Dough 's solution will need too much tweaking but will be a better one in the long run.

              Jan's solution has one issue- the cloth worn tightly will be uncomfortable over time.

              But I'm getting good ideas. More inputs please.

              2 of 2 people found this helpful
                • Re: Sensing Baby Kicks
                  Jan Cumps

                  In my defence, I'm going to suggest to buy stretching resistive cloth

                  2 of 2 people found this helpful
                    • Re: Sensing Baby Kicks
                      Jan Cumps

                      http://openmaterials.org/materials-101-electrotextiles/

                       

                      Electrolycra from Mindsets: looks and feels like ordinary lycra but it’s highly conductive. Its conductivity in one direction depends on how tightly it is stretched – if you pull it the resistance increases and then drops again when stretched even tighter. When cut into a thin strip, the material also warms up when current is passed through it and can thus provide the basis of a heated garment. A 6V battery will cause an appreciable warming effect. Resistivity: 5 ohms per 100mm, increasing to 20 ohms when stretched to 150mm. If the material is turned through 90º and stretched the resistance drops to 2.5 ohms

                      3 of 3 people found this helpful
                      • Re: Sensing Baby Kicks
                        Jan Cumps

                        jancumps wrote:

                         

                        In my defence, I'm going to suggest to buy stretching resistive cloth

                        And you could let mom remove and re-apply it every day to her own comfort, then press a callibrate button, and start measuring deltas.

                        The movement caused by the breathing of mom can be filtered out because that happens in a known frequency spectrum, much slower than the kicks and punches of little baby Singh.

                         

                        Needs to be switched off when mama has hiccups and during morning sickness bursts

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                    • Re: Sensing Baby Kicks
                      ipv1

                      I have sought out some stretch sensor wires and will be trying them out. The rest of your hypothesis will take some time to test out and I will update as and when.

                       

                      I am also going to continue experimenting with the piezo sensor and might try some surgical tape for temporary adhesion. There seems to be no solution currently available for a comfortable wearable...

                      3 of 3 people found this helpful
                      • Re: Sensing Baby Kicks
                        kholt62

                        Were you able to figure this out? Sure would love to give it a try!

                          • Re: Sensing Baby Kicks
                            dougw

                            I would develop something like this is my wife was pregnant - maybe play some music as feedback for the baby. I have developed a soft belt with sensors that could be used for this. It was developed for physiotherapy applications, but it would easily sense and discriminate a baby kick.

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                              • Re: Sensing Baby Kicks
                                kholt62

                                Hi Douglas,

                                I love the music idea. Could you share it with me? I have a lot of time on my hands right now. LOL

                                  • Re: Sensing Baby Kicks
                                    dougw

                                    Early learning is a fascinating topic. I have some very old memories of sensations from before I could talk. I cannot vocalize them well because I had no language to describe them, but some sensations trigger those memories.

                                    Lots of studies show that unborn babies respond to sounds and music, altering their activity or their heart rate. Some studies show that late in pregnancy babies can even recognize their mother's voice.

                                    Beyond just providing richer stimulation through audio, it would be interesting to provide information, in case it is possible for some level of learning. For example if they always hear "standing up" when the mom stands up or "lying down" when she lays down, maybe they would start to associate words with sensations they are actually experiencing.

                                    Or if they always hear "kick" when they kick, maybe they would associate with the action. It would be cool if you could say kick and the baby kicks in response.

                                    Of course the Mom could just talk to her baby, but acoustic coupling from air to a body is very inefficient and dramatically attenuated.

                                    I would use a surface driver like bone conduction headphones to provide audio at a low volume - it wouldn't require much volume to couple into n the womb, since the surface driver would directly vibrate the Mom's skin surface. The system could be used to talk to a baby more efficiently, or it could be used to provide automated feedback based on sensors such as a kick sensor or a tilt sensor.

                                    Many mothers have tried audio stimulation of their babies and some claim it is a critical part of early development, but it is wise to check out what is considered safe and what others' experiences have been.