Donut420 (The Hong Kong Polytechnic University)


Donut 420

Tony Lau, William Ko, Sarah Tsui, Shan Law, Ann Chan 


Washing tableware is challenging for people with upper limb dysfunctions or those with one hand only. They either need to perform lots of in-hand manipulation for smaller bowls, or could not stabilize the larger containers. Donut 420 is designed to assist them. It consists of a stainless steel frame with a cone shape to accommodate different sizes and shapes of plates and bowls. Non-slip material covers the inner side to stabilize the tableware. At the base, sucking discs help anchor the product on the sink securely.  There are holes at the side for water drainage. The tool is fixated on the sink with sucking discs.  Smaller bowls are placed at a lower level of the frame while larger tableware could be fixated at a higher level. By using Donut420, users could simply hold the scouring pad to wash the containers with only one hand efficiently.


Dishwashing is a task which required repetitive use of hand bilaterally. This may cause difficulties to people with upper limb disability such as hemiplegic stroke, repetitive Sprain Injury, single arm amputee and other upper limb injuries. For people with single arm amputation, they only have unilateral hand function. They have problem stabilizing the tableware in the sink while using one hand to clean.

For people who suffer from hemiplegic stroke, their affected side is either paralyzed or weak.  Their grip strength is inadequate for holding the tableware and dexterity for manipulation of tableware is poor. They also have decreased physical endurance.

For people with cumulative traumatic disease, such as Carpal Tunnel Syndrome, they have hand numbness and reduced strength on the affected hand and repetitive hand movements in cleaning task will aggravate the hand conditions.

Our client, Miss Yeung suffered from stroke, affecting her left side of the body. She has diminished hand strength and dexterity. There is numbness in her left hand. She also suffered from low back pain and with generally low physical tolerance for around 10 minutes. For her, one important instrument activities of daily living is to wash the tableware as she is living alone in a public housing estate. However, her current ability is limiting her participation and performance in this area.

Our goal is to design a device to assist her to wash the tableware using her right hand and also help her for energy conservation to finish the task efficiently.


Miss Yeung needs a device to help wash the tableware using one hand efficiently. The goal is to improve the ease and efficiency of the cleaning process. We hope to improve her independency in washing tableware and so improve their quality of life.


Washing tableware is a challenging task for people who have lost one hand function.

In Hong Kong, most of the family do not have dishwasher. They either need to perform a lot of in hand manipulation for smaller bowls, or they could not stabilize the larger containers. Donut 420 is designed to assist this group of people.

By stabilizing the dishes on the product, users are able to use one hand to wash efficiently. As the tableware is fixated in the device, users only have to hold the scouring pad to wash them by one hand, rather than holding and turning them for washing with both hands. This requires less strength and energy. The steps of operating it includes:

  1. Fixate the device on the sinkStabilizing the tableware
  2. Put the tableware in a suitable position inside the devicewashing smaller dish
  3. Add detergent and clean with single hand
  4. Rotate the tableware for thorough cleansing if necessarywashing larger dish
  5. Take out and rinse the tableware with water

Donut 420 consists of a simple design of a stainless steel frame. Stainless steel is chosen as it is corrosion resistant, tough and unlikely to be damaged or deformed. It has a cone shape to accommodate different sizes and shapes of plates and bowls in Hong Kong. The cone shape design also increases the contact surface area with the bowls and dishes for better stabilization, as common Hong Kong tableware are round in shape.  The maximum and minimum of diameters of the inner space are 8 inches and 4 inches respectively. These figures are based on the size of the tableware common in Hong Kong. The height of the frame is 8”, which is comparable to depth of sinks in Hong Kong.

There are five non-slip strips in the inner side to stabilize the tableware. The non-slip material used for the strips is PVC mat. It is spongy to accommodate different shapes of tableware. There is also a silicon ring covering the top edge. It can be used to stabilize large plates and dishes securely. Silicon can be easily cleaned.

There are pores at the side for water drainage. At the base of the frame, there are 3 suitable sucking discs to anchor the product on the sink surface securely. The sucking discs can be easily removed for maintenance.

Users first remove the large food debris in the tableware before using. Then, fix the device on the bottom of the sink. The tableware is put in a suitable position inside the device. After adding detergent to the scouring pad, users can clean the tableware with single hand. If necessary, the tableware is rotated for thorough cleansing. Finally, the tableware is taken out and rinsed with water.

Regarding maintenance of the device, it should be stored in a ventilated and dry place. Also, for hygienic consideration, device needs to be rinsed after use to prevent accumulation of food particles in pores.


Donut 420 was evaluated for its application in terms of its appearance, method of control, comfort, safety, durability and accessibility. Miss Yeung has tried to use the device in cleaning dishes. Its colorful appearance is acceptable to her. It is easy for her to use the device. Donut420 has enabled her to adopt one hand method and also reduce her effort in cleansing tableware for energy conservation. The device sticks to the sink firmly so the device will not detach easily during the cleansing process. Moreover, using this device, the client does not have to flex the trunk as the upper part of the device act as a platform to clean larger dishes, relieving her discomfort due to low back pain.


There is no similar design in the market. For people with single hand function, it is likely for them to use non-slip mat only, or placing a dish drainer on the sink to help fixate the tableware. Others may consider using dishwasher, which is not very common in HK. Also, there are some designs trying to fix the washing tool such as brushes or sponge.
For non-slip mat, there is only a small contact surface between the mat and the tableware, which would be unstable and the effect of non-slip mat would be reduced if the tableware is oily.  The dish-drainer may not be able to stabilize tableware securely and the size of the dish-drainer is quite large which may not be accommodated in sink in most of the kitchen.

Compared to dishwasher, our device is simple and intuitive to use. Also, our product is much cheaper than a dishwasher and does not need electricity. Our product, which is of appropriate size, occupies much less spaces than dishwasher. In order to achieve maximal efficiency of the dishwasher, users may have to accumulate dishes until maximum capacity is reached. This may cause hygiene problem and inconvenience if the user is living alone. If the user uses our product, he or she does not have to accumulate the tableware.

Regarding the designs which fixate the washing tool on the sink, our device is different from them in a way that we try to fixate the tableware instead. In this way, users only need to hold the scouring pad instead of the heavy tableware and do not need a lot of manipulation. Strength and energy is conserved.

The material cost of the whole device is less than 60 Hong Kong dollars.  If it is put in mass production, the cost would be much lower. Therefore, it has the potential to be developed in the future and helps more people with disability in doing such exhausting household task.


We would like to thank Miss Yeung for helping us experiment Donut420 and the assistance provided by the Hong Kong Society for Rehabilitation. It was a grateful experience to try our device on real clients. Moreover, this would not have been possible without Dr. Kenneth Fong and Mr. Peterson Chui, who gave us advice during our design and implementation process.


  1. Bumphrey, E. E. (1987). Occupational Therapy in the Community. NH:Woodhead-Faulkner Ltd.
  2. Crepeau, E.B. and Schell, B.A.B. (2009). Analyzing Occupations and Activity. In E.B. Crepeau,E.S. Cohn, B.A.B. Schell (Eds.)
  3. Crepeau, E.B., Cohn, E.S. and Schell, B.A.B. (2008). Willard & Spackman’s Occupational Therapy (11th ed.). Philadelphia: Lippincott Williams & Wilkins. Chapter 34, p. 359-374.

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