Microchip cat flaps

[hypotypo]

We have a Sureflap cat flap that works really well with our older cat’s microchip. The problem is that we also have a kitten who is desperate to be outside but is still too little. The cat flap lets any animal leave the house regardless of microchip so we are having to use the manual settings and lock the flap, only allowing the big cat to come in. He then gets trapped inside with the kitten who can be pretty annoying.

We are going away and I can only think we are going to have to keep the cats separate so that the big cat can go in and out but the kitten can’t escape. This will mean shutting them both into relatively small areas of the house and them having a few minutes together when someone comes in to feed them.

Does anyone know of a cat flap that only allows microchipped animals to leave the house? This would make everything so much easier all the time, not just when we are away.

Sympathy, OP, I remember those days of one in one out! Sureflap make a model called Dualscan that allows exit permissions to be set for each cat. I don't have one so I can't tell you how easy it is to set up or how well it works, but I do have their regular model, perhaps similar to yours, which I agree works well so I'd be tempted to try it.
If you can't fit it before you go away this time, would you consider keeping your older cat in too, or would that cause fisticuffs? Even with plenty of toys and a Feliway?

Thanks, Poppychop. I will look into that cat flap. Sadly I think we would return to a single cat if we left them together without big cat having a means of escape.