Write Right

As part of an Engineering Design course in Biomedical Engineering, we encountered a common problem among students during exam preparation – wrist pain caused by prolonged writing and excessive pressure on the pen. One of our team members suffered from this issue, and we decided to take on the challenge and develop a solution to help prevent this discomfort.

The solution we developed is "WriteRight" – a product that combines an electrical circuit, an Arduino, a pressure sensor, and an LED to detect the amount of pressure applied to the pen during writing and alert the user. When the user exceeds the predefined pressure threshold set by the code embedded in the Arduino, a little (but strong!) LED light turns on, providing immediate feedback, alerting the user to adjust their grip and lighten the pressure. The pen is set to prevent potential wrist injury and promote healthier writing habits.

The product is designed to be compact and user-friendly, with a box that we designed using Solids and a 3D printer. The box securely houses all the electronic components includes the product name on its surface, and features a designated spot for a switch to turn the device on and off. Additionally, there is an opening for a wrapped wire connected to the pressure sensor, allowing it to extend out of the box and be attached to the pen using Velcro for easy and secure sensor placement.

The system would fit any pen you choose, just attach it with the velcro, and you'll be ready to write right!

You'll need the following components for this project:

UltiMaker S5 3D Printer- Link to purchase

12.7mm Round Force Sensor- Link to Purchase

220 Ohm Resistor- Link to Purchase

10 kOhm Resistor- Link to Purchase

Blue LED Diode- Link to Purchase

Mini PCB Soldering Board- Link to Purchase

8 Copper Electrical Wire- Link to Purchase

One 9v Battery- Link to Purchase

ON/Off Mini Slide Switch- Link to Purchase

ARDUINO UNO R3- Link to Purchase

Work Fan for Soldering Station- Link to Purchase

Welding and Soldering Kit- Link to Purchase

Make sure you have all the necessary components and tools before starting the project. This includes the Arduino UNO, resistors, force sensor, LED, 9V battery, mini PCB board, electrical wires, switch, Soldering Kit, WorkFan for Soldering Station, and access to a 3D printer for printing the parts.

Start with measuring the Arduino, battery, mini PBC board, and switch. Using these measurements, you'll be able to create the box that's perfect for your needs.

Using CAD software like SolidWorks, design a basic box that will securely house the Arduino board, PCB, and other electronic components, based on the size of the parts you choose. Opt for a small design, to make carrying the product more comfortable. The design should include built-in openings for the switch, LED, and a slot for the pressure sensor wire to exit and attach to the pen.

Our box consists of a middle lid as well, that hides all of the components and only leaves the LED exposed. If you want to build that as well, design support bars on the inner corners of the box to hold it up. The middle lid should include an opening for the light and small handles for easier removal.

The STL files for our specific design are attached for immediate print, as well as the files that can be viewed directly in Solid.

Box Sizes For Basic Design

The box itself is 130mm in width and 80mm in length on the outer part. It has 3mm thick walls that are 50mm high.

The lid is 130mm in width and 77mm in length and 3mm thick.

The additional middle lid is 121mm in width and 71mm in length.

Pring Settings

All 3D printed parts were printed with a layer height of 0.2 mm and the default infill rate (around 15-20%), and the filament used was PLA. The colors we had available were yellow and pink. Additionally, if the supplies are available, the top lid can be made transparent, making the light visible without having to open the box.

Place the Arduino UNO on a soldering board and connect the force sensor, LED, resistors, and switch according to the circuit diagram, and these steps:

1. Place the breadboard next to the Arduino for easy wiring.
2. Insert the 220 ohm resistor on the breadboard. One end of the resistor end will be grounded, and connected to the Arduino's GND port (brown wire).
3. Place the LED on the board- the negative side will be on the same column as the second end of the resistor.
4. Connect the positive side of the LED to the 11th port of the Arduino (yellow wire).
5. Place the 10k resistor on the other side of the breadboard. Ground one end to another GND port on the Arduino (green wire), and the other to the A0 port of it (gray wire).
6. Connect the pressure sensor. Connect one side to the 5V port on the Arduino (red wire), and the other on the same column as the resistor and its connection to the A0 port (blue wire). Use an extension if needed.
7. Connect the 9V battery to a DC barrel jack connector.
8. Plug the barrel jack into the power port of the Arduino Uno to provide external power to the board.
9. Use two additional wires to connect the switch to the battery.

Double-check all connections to ensure they are secure and correct before proceeding to the next step.

Connect the Arduino to your computer. Write or upload the provided code to the Arduino that reads the input from the force sensor and triggers the LED when the pressure exceeds a predefined threshold. Make sure the code is calibrated according to the user's writing pressure.

The pressure we defined as the threshold is based on multiple tests done on the user's writing, taking the average of all readings.

After successfully testing the circuit on the breadboard with the Arduino, solder the components onto the mini PCB board. This step ensures the circuit is durable and compact, fitting neatly inside the 3D-printed box. Use the Work Fan for the Soldering Station to ensure a safe and efficient soldering process.

Try to make the LED pop out of the mini PCB as much as possible, to make it visible later on.

Before assembling all the components in the box, conduct a thorough test of the entire setup.

Connect the 9V battery and turn it on, place the sensor on the pen using velcro, and verify that the LED lights up when the pressure threshold is exceeded. Make any necessary adjustments to the code or hardware.

The Box

Place the Arduino, PCB, and other components into the 3D-printed box. Secure the components using screws or adhesive if necessary. Attach the switch to its designated slot and ensure the pressure sensor wire exits the box smoothly and is long enough to attach to the pen.

The Pen

Wrap the wire connected to the pressure sensor around the pen using Velcro straps. Position the sensor where the user's fingers typically press on the pen, ensuring it is securely attached and can accurately detect pressure.

Now that your WriteRight device is fully assembled and tested, use it during your writing sessions. Enjoy the comfort of writing without worrying about wrist pain, as the device will alert you when you applytoo much pressure, encouraging healthier writing habits.