• Son Luu

Door Stop Sandal - a Chindogu

Updated: Mar 17, 2020

A Chindogu device that is remotely controlled by another device... Hmm... What an interesting prompt. Who still uses remote control anyways, while many have moved on to voice controlled devices and home appliances 😊? But, that's what's going to make this product unique and whimsical in its own way, using not so modern technology to solve a daily life problem. In addition, the remote control can use a variety of telecommunications technology, including: WIFI, radio frequency, or an IR (infrared light) receiver etc. which can offer interesting applications.

Team members:

Shuju Lin: Ideation, technology application development, prototype fabrication

Myself: Ideation, technology application development, prototype fabrication


At the time of this project, there is a serious concern with public and personal hygiene while dealing with the spread of the Corona virus pandemic in late 2019, through 2020. One of the most crucial and frequently recommended by heath care professionals to the public is to thoroughly wash hands often throughout the day. This is due to the possibility of the disease being spread via being in contact, or touching public objects, surfaces around us. This is even more serious when in very busy, or major publicly used facilities such as subway stations, workplaces, stores, etc.

The situation sparked an idea to solve a problem that we often face which is touching door handles/knobs when passing through public areas. But hold on a sec, what if that door or gate is already swung open, and you could just run through it without having to push it or touch the door handle to open it? Except, if you're still a distance away from the door, then all you need is something to run faster than you to the door and hold it open for you to pass through.

A Chindogu Inquired Solution

Inspired by the saying "A foot in the door", referring to an opportunity to achieve an initial stage or succeed with a first step, we came up with the idea of a sandal (one foot) that can be remotely controlled to direct it to run to the door and hold it for its owner.

The Tech

We decided to use radio frequency receiver for this project for the following reasons:

- not having to rely on public WiFi access

- relatively short-distance communication between two devices

- not requiring high power supply

- not relying on direction of remote control (unlike IR sensor, for example)

- relative quick response (at least for just turning on/off a device)

Technology Testing

Test No. 1: Initial test using 315 MHz Radio Frequency (RF) Receiver to control both LED lights and a DC motor. DC motor runs very slow at first.

Test No. 2: With the same basic set-up, second test shows the DC motor is able to run faster but the remote control needs to be much closer to the receiver.

Test No. 3: This test showed that the speed of the DC motor has nothing to do with the distance between the remote control and the receiver; instead, the electric wires were our problem.

Test No. 4: Running RF receiver and controller with some newly ordered DC motors with wheels attached to them.

We decided to run the motors with a 9V battery pack and the Arduino was still powering the RF receiver. The remote control has its own battery.

Next, we made a quick prototype of a platform to sit on top of the dc motors and their wheels to see how they run.

We quickly realized that the 9V battery pack is very heavy, which is not ideal to be carried with other electronic components on top of these small motors.

At one point we hacked into a small toy car to explore other technical design options for internal components and see if we could apply any similar techniques. However, it wasn't very helpful although now we know what's inside these little toy cars.

At this point, our goal is to be able to independently power the entire system with external batteries without carrying too much weight. We tried several different options. The biggest challenge was not to find light weight batteries, but gathering enough voltage at sufficient electric current amperes that can appropriately and safely power our motors.

After many hours, we ended up with a small external power bank (5V supply at 3A), a 9V battery pack (1.5A).

Design and Fabrication

Initially, the idea was to hack into a shoe and have all the electronic components stored inside, but we ran into 2 problems: (1) to break into a shoe (especially a high quality, tough sneaker that we could find) was challenging and time-consuming, (2) the radio frequency was not received consistently when the receiver was stored completely inside an enclosure, which also discouraged us from going with a body design that may be too thick.

But, we tried anyways!

We started off making an enclosure to store the electronic components with the intent to eventually have the shoe sit on top of this enclosure

Apparently, the process of breaking into a shoe involves soaking it into boiled water.

Then, the shoe can start to undergo the cutting operation!

We ended up deciding that this "time and effort-consuming" process was going to take more time and labor than what we had hoped for, so we decided to pivot to a new design idea - light, quicker, and also providing an aesthetics that could give it a whimsical design story to the product. That is a Japanese styled sandal.

With the new design concept in mind, we were confident the product will be finished in time and within budget.

Below are some of the very intense labor intensive making process of the remote control handle and the overall aesthetics of the sandal.

A big part of the making process is to break into the parts and components to explore how it is design internally, so that if we decided to hack into these components to incorporate our design, we would be able to maintain the functionalities of these components.

Final Product