Police Pocket


‘Police Pocket’ is an anti-theft alerting system. It is a sound-based, portable and detachable pouch which can be placed in any pockets to contain wallets. The intended user could be anyone who uses a pocket (lol…just kidding!). I have conceptualised this idea while travelling in a Subway one day when I came across a post saying “Beware of Pickpocketers”. This is a solution-oriented design, the response mechanism consists of a sound out via the speaker of the Adafruit playground Circuit which triggers on a saying ‘Intruder Alert’ when the user’s wallet is taken out of the pocket using the Talkie library in Arduino. The interface sits in the pocket and is liked to the Adafruit circuit which stitched below the wrist. 

The interaction is small, portable, direct and simple. It sesses action of a pickpocketer. Whenever a purse cutter tries to takeout the purse, the speaker shouts ‘INTRUDER ALERT’ and all the NeoPixels blinks into Red from Blue. This cautions the user and saves his/her wallet from getting stolen. The interface is rough, informal and uses a variety of materials – 

  1. Conductive Fabric (1 Digital Switch)
  2. Resistive Stretch Fabric (1 Analog Switch)
  3. Conductive Thread – Run and Whip stitch (Connecting the circuit & ‘Police Pocket’)
  4. Non-Conductive fabric (Floral embellishments, pocket pouch & decorating Adafruit Circuit)
  5. Insulation tape (Covering the conductive wires)
  6. Alligator Clips (making the ‘Police Pouch’ detachable & Portable)
  7. NeoPixels (Turns red from blue gradually when the wallet is being pulled out)
  8. Speaker + Speech Library (Calling Intruder Alert)

One material I would have used instead of the conductive thread was copper strip as they are easy to use (applied as a tape), more reliable and better conductors. I would buy them from Creatron.Inc.


Work-in-progress images:


prototypewhatsapp-image-2020-01-29-at-8-21-43-am whatsapp-image-2020-01-29-at-8-22-25-am

Portfolio Images:

playground-blinking whatsapp-image-2020-01-30-at-5-46-51-pm whatsapp-image-2020-01-30-at-5-46-53-pm



Mechanism – Police Pocket

Police Pocket



GitHub Code


Schematic Diagram:


Project Context:

Ideation + Research: Initially, after reading the brief I started browsing different kinds of existing ‘Smart Wearable’ projects. I tried reading the examples shown in the class. However, the portfolio of Koba – An e-textile tailor shop by KOBAKANT inspired me the most. I looked up to their projects like the Crying  Dress, Star Light, Musical Pillow and several other DIY projects. The best feature of their works is that the authors/designers have created them open-sourced and easy to make. These gave me numerous ideas on how to use conductive materials as switches and sensors.

I knew I wanted to make my design solution-oriented and meaningful. In this modern era, with the rising number of thieves, tricksters and pickpocketers. I thought of creating a DIY anti-theft pocket since the existing ones in the market are expensive and monochromatic. My intention was to create a do-it-yourself project which is made of cheap and accessible materials.

Prototyping: My project is inspired by the (1) “Star Light”- where the conductive thread is used as an on/off button. When tied, the circuit gets completed  & the sewable lilypad LED turns on. I used 2 pieces of the conductive fabric as a digital switch. One piece is attached below the wallet & the 2nd piece is attached in the pocket. When the wallet is taken out of the purse, the circuit gets completed and the speaker calls out ‘Intruder Alert’. In addition to the process, I have incorporated ‘the resistive stretch fabric’ as an analog sensor – converts the NeoPixels into Red from Blue gradually when the wallet is pulled out completely out.

Coding: I have incorporated the ‘Talkie Library’ – A library that enables the Playground Circuit with speaking and pronouncing capabilities. Using it can generate phonetic sounds and read alphanumeric values. I got this idea when the saw the project “(2) Talking Temperature Readings on an Adafruit Circuit Playground Express”. I used the Talking Library for the first time & explored various quotes using a combination of the 26 coded alphabets and already given words to alarm the user like-

  • Thief! Thief! Help!
  • Don’t take my purse
  • Help!
  • Thief Alert!
  • Intruder Alert! (finally used)

Finalising: After testing out the codes on analog and digital switches. I started placing my design on my jackets & its pocket. I used conductive thread to connect the circuit and the switches. I made a dummy pocket since it is difficult to stitch in the jacket’s pocket because I could not see where I was stitching. To lock the sides of the fabric I used ‘Whip Stitch’ technique, otherwise, in most of the cases, I have utilised the ‘Run Stitch’ technique. The alligator clips are used to hold the pouch and my wallet inside the jacket’s pocket which links with the conductive wires to make the material portable, detachable and light. My intention was to create this pocket conveyable and transferable with any garments that include a pocket. The last step was to cover all the conductive wiring which was troublesome and hectic (since wires go inside the pockets and sleeves of the jacket) with the insulation tape to protect the mechanism & avoid disruption.


  1. Perner-Wilson, Hannah, and Mika Satomi. “KOBA”. Kobakant.At, 2018, https://www.kobakant.at/DIY/?p=2036. Accessed 20 Jan 2020.
  2. Perner-Wilson, Hannah, and Mika Satomi. “HOW TO GET WHAT YOU WANT”. Howtogetwhatyouwant.At, 2012, http://howtogetwhatyouwant.at/?cat=179.
  3. Hartman, Kate. Make: Wearable Electronics. Maker Media, 2014.
  4. Adafruit Learning System. (2020). Make It Talk. [online] Available at: https://learn.adafruit.com/make-it-talk?view=all [Accessed 26 Jan. 2020].
  5. Perner‐Wilson, Hannah & Leah Buechley. “Hand Crafting Textile
    Sensors.” Textile Messages: Dispatches from the World of E‐Textiles and Education, edited by Leah Buechley, Kylie Peppler, Michael Eisenberg, & Yasmin Kafai, Peter Lang, 2013, p. 55‐65.



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