Kids climb up --- shelves fall down, so anchor the shelves to the wall or the ground. Still they'll climb and maybe fall, from the shelves upon the wall.
Though eyes keep watch on the tykes all day,
once in a while they still slip away. What's needed are some e-lectronics, to help them live to learn
Near front edges of the shelves where little fingers perch themselves, would be some sensors on a strip which when touched, an alarm would trip.
Their conductive digits grab the shelves when little ones climb to injure themselves. The sensors would detect the little squirt and rat out the rugrat with a sonic alert.
Details: (feel free to make your own rhymes)
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The sensor would be placed flat on the shelf near the front edge. This sensor strip would be an unobtrusive, very thin, transparent substrate with conductive traces on the exposed surface. (Similar to some flexible circuitry I've seen that appears to have been printed on the substrate. I've seen such circuits in Microsoft Natural keyboards and a more robust version in automobile instrument clusters).
The flat sensor strip would be formed in a "T" or "L" shape so that it could connect with the circuitry and audible warning device located inside a faux book on the shelf.
If shelves are of the appropriate construction, conductors from the sensor strips could route up/down the back of the shelving unit so that many shelf edge sensors could be served by a single alarm unit. Otherwise, one system per shelf. It would likely suffice to have this device on just one key shelf in each vertical span.
Aesthetically, the plastic of the sensor strip could maybe be treated to be non-reflective like eyeglasses to make it less visible. The conductive traces could probably be tinted in tones that would prevent it from clashing with the color/grain of the shelf material.