A hi-tech collar which claims to measure the mood of your dog and cat is unveiled at an expo of wearable devices in Tokyo.

A wagging tail is usually a sign that your dog's happy enough, whereas cats can be more inscrutable. Now this new hi-tech collar from Japan claims to take a scientific approach to your pets' emotions.

Equipped with two sensors which detect the speed, motion and bodily rotation of pets, the device sends measurements to a phone app.

The data's then translated into four possible results: excited or happy, relaxed, wanting to play and annoyed.

Developer, Masayoshi Asahi, saying:

"This machine displays the emotions of animals by translating the vibrations from the movement of the tail, their cry, and the trembling of their body into a gauge for how they're feeling."

Former Dog Owner, Wakaba Sakai, saying:

"I'm interested in this device because it makes me feel like I can communicate with pets."

Also in the spotlight at the expo of wearable technology in Tokyo was this smart sportswear which measures body posture.

The stretchable sensor determines the position of your body and sends the data to an app, allowing users to monitor whether they're sitting correctly.

The t-shirt's expected to hit the market at around $85.

Businessman, 52, Takehiro Hasegawa, saying:

"I would definitely buy this if my back and shoulders really hurt. The price is nothing because it's for my health."

The expo is the world's largest for wearable devices and saw more than 210 exhibitors displaying their new technology.