Secret Letter

Smart stationery-product prototype

  • At: Taipei International invention and technology trading exhibition, Taipei WTC
  • By: Tuomo Tammenpää & Dimension Plus, TW
  • To: ITRI, Taiwan
  • In: September 2017


“Secret Letter” is a prototype for a playful stationery product. The idea is based on “smart letters”, paper sheets with RFID tags hidden inside. The customers can buy these blank letters, write their message on them with pen and add a secret digital message in the RFID/NFC tag, using  accompanied phone app. Letters are mailed by post and the recipient can read both the visible mesasage and the secret message. Design thinking behind the concept is based on two claims: 1) physical message is precious and 2) the promise of secrecy raises curiosity. In the times of social messaging and information overload, sending and receiving a physical message, a letter or a postcard carries more value. For example. handwritten love letter with a secret part visible only to the reciever will feel very special. Also, in general, adding digital content to physical objects opens new possibilities for sharing and saving memories.

There are several potential target audiences for NFC enchanced stationery products. Playful examples include romantic love letters or secret letters between best friends, targeted for teens and young adults. However, this kind of product needs a reminder of the value of a physical letter, in the times of hundreds of short messages during the day. The two-part message concept: one visible, one hidden, opens also game-like applications, from question-answer combinations like riddles to lottery tickets or scratchcards. The secret message can be also used as a link to any digital content stored online or trigger more engaging interaction on the phone app client. Technically, the market is ready for NFC based applications. Two out of three phones ship with NFC in 2018 due to the increase of mobile payment systems and even Apple has opened it’s NFC chip for developers. Also, the emerging Blockchain technology opens up new possibilities on securely storing data on a distributed network, and enabling game-mecahnics like collectibles and chain-letters with long-tail built-in to the service.

The Secret Letter was inspired by the silver ink antenna- and circuit technology by ITRI. Concept started from envisioning an idea of a “super material”, where one could combine properties like printed circuits and antenna design with memory alloys for actuating motion or pressure sensitivity for capturing user interactions. The process focused on adding memory in to physical objects, where a tag can store bit of information or link to information online. For storing short text information, a small secret felt the most precious and the idea crystallised to a “smart letter” -product. Next, embedding the tag between two sheets of paper was experimented and this worked well with thin sticker tags. However, the affordance of keeping the tag visible had usability value, and this, combined with aesthetic qualities of silver ink ornament, led to the idea where the tag could be visible.This prototype models the idea of antenna design as a functional brand label for the Secret Letter -product

Secret Letter prototype was an outcome of a “Prototyping Workshop”, organised by ITRI Taiwan and produced by DimensionPlus in Taipei, April 2017