Several months ago, my wife had a bad fall at her workplace which shattered her wrist, requiring multiple surgeries to repair, complete with embedded steel plates. As a result she has been forced to retire early, but it could have been worse and the next fall could definitely be worse.

Almost half of all injury-related deaths among seniors in Canada are caused by falls. The cost to those individuals is the ultimate - their life, but the cost to survivors is also huge in terms of suffering, loss of independence, reduced quality of life and cost to the health-care system. The Public Health Agency of Canada estimates one in three people older than 65 will fall at least once a year, a rate that increases to one in two for people over the age of 80. This means about 1.3 million Canadian seniors will fall this year.

Seniors are Canada's fastest-growing population - in 2001, seniors already made up about 12.6% of the Canadian population, in 2011 this rose to 14.4% and in 2021 it will be 18.5%. Unintentional injuries caused by falls are the costliest category of injury in Canada. Across Canada, the combined social and health care cost of falls on stairs alone has been estimated at $8.8 billion a year. Falls on steps and stairs account for about 60 per cent of hip fractures and can result in head injuries and other broken bones.

At least one senior in Ontario visits an emergency department every 10 minutes because of a fall; every 30 minutes at least one is admitted to hospital.

If the problem of falls isn't addressed it will get worse because of the growing number of seniors.

Between ages 50 and 65, the risk of a wrist fracture increases and eventually plateaus. But from age 60 and on, the risk of a hip fracture increases exponentially with each passing year. One in five women will have a hip fracture by age 80, one in two by age 90.

Research shows that up to 40 per cent of seniors who've tumbled and fractured a hip will die within six months, often because they've developed pneumonia or other complications. As awareness builds in the community, the fear of falling also increases, which leads to less exercise, which leads to higher risk of falling in a vicious spiral.

To reduce health care costs and increase quality of life it is very important to keep seniors living at home as long as possible and exercise is essential in this initiative. For seniors, exercise means getting out of the house and walking.

The risks and consequences of falling have traditionally been unreported and just an accepted, unavoidable consequence of living in this climate, but there are things we can do to reduce the problem. Slipping on icy steps is a major cause of injury in Canada and is a concern for everyone, but particularly for seniors.

Another serious issue in Canada are injuries and heart attacks due to shoveling snow to clear walkways and driveways. Shoveling snow and chiseling ice are strenuous activities that account for at least a 20% increase in heart attacks and the risk for seniors is about 4 times higher than for younger people. As bad as these heart attack statistics are, the risks of other injuries while shoveling snow and ice are 10 times higher than the risk of heart attack.

The Problems I Want to Address

In Canada, most dwellings have steps leading up to the front door and every place in Canada can experience ice and snow on these steps.

I want to design a system that can automatically clear ice and snow from steps, walkways and driveways, thus reducing the incidence of injuries and heart attacks from snow clearing efforts and from falling on icy steps and walkways.

The solution needs to be easy to use, have a low carbon footprint and not put people at risk of falling or heart attack.

Snowy Steps

Walkway sill has dangerous residual ice and snow after shoveling

The Solution

I want to make a solar powered machine that will use solar power to melt snow and ice on walkways and steps, even when the air temperature is well below the freezing point of water. The system will use a mirror to focus sunlight on icy areas until they are clear. Sunlight supplies about 1 KW/m2 or 93 W/ft2. If output from a mirror is added to the normal sunlight power on the target area we would almost double the power to an area from about 90 W/ft2 to about 180 W/ft2. If our mirror is 8 square feet, this would be 700 Watts from the mirror or a total of 1400 Watts to the target area when combined with direct sunlight on the target. This is enough power to raise the temperature of the surface by 20 to 30 degrees C depending on wind conditions and the reflectance of the snow and ice. A simple black mesh screen laid on the target surface could dramatically reduce reflectance and increase conversion from light to heat, but any dark object sticking up through the snow will get the process started and it will spread as local snow melts and more dark surface becomes exposed. To keep a mirror continuously focusing sunlight on a target area, the system will need to know where the sun is at all times and to know where the target area is as well as knowing its own position. It will also need to be able to rotate the mirror in 2 axes to accurately redirect sunlight to the target area.

To make the system easy and safe to use it needs to be operated remotely from inside the house. The user would simply aim the mirror at a patch of snow or ice via bluetooth using an android app. The system would then keep the mirror focusing sunlight on the target spot for a specified time. Alternatively, the system could be setup to incrementally and automatically “sweep” an entire walkway with pre-determined dwell times based on ambient temperature and depth of snow.

The electro-mechanical mirror system would be mounted to form a sunshade above a park bench in the front yard. At that height, it would provide a reasonable angle to the target area. This position would also disguise the apparatus somewhat as it could look like a sunshade, but it may mean the entire bench would rotate when tracking the sun. This rotation would be slow, but needs to be powerful enough to move through any snow in the way.

Clear Walkway

Clear walkway one day later without further shoveling, just mildly focussed sunlight (still -10 degrees ambient)


  • Melting and evaporating snow and ice is eventually far more effective than shoveling because shoveling inevitably leaves dangerous patches of ice and snow.
  • Automatically melting snow and ice will significantly reduce the requirement for strenuous snow clearing efforts and dramatically reduce the likelihood of slipping on ice and snow.
  • Reduced injuries and heart attacks will save health care costs and improve quality of life.
  • Clear walkways will reduce fears of falling and encourage seniors to go out and get walking exercise.
  • Making the system entirely solar powered, reduces greenhouse gas emissions and saves on energy costs.
  • When all ice and snow has been cleared, the system can be used to send sunlight into windows, providing light and heat that reduce energy requirements, and potentially even helps indoor plants grow.

If that isn't enough, here are 15 ways sunlight helps people:

  1. It cheers you up. Sunshine boosts levels of serotonin - the body's natural happy hormone. That's why we tend to feel happier and more energetic when the sun shines. Regular sun can stave off moderate depression, particularly if combined with exercise, such as a walk in the park. It's also been shown that exercising outdoors creates more endorphins in the body than exercising indoors.
  2. Reduces heart disease. A study in the British Medical Journal showed that people in the UK are more likely to die of heart disease in winter than in summer, which is believed to be because of low levels of vitamin D. Where you live in the UK also matters. Blackpool has 27 per cent more hours of sunshine a year than Burnley - and 9 per cent fewer deaths from coronary heart disease. Cholesterol levels also rise in winter, according to reports in medical magazine The Lancet, and this is because our vitamin D levels fall. And Dr Holick found that exposing people with high blood pressure to UVB rays in a tanning salon lowers blood pressure by similar amounts as prescribed drugs.
  3. Prevents diabetes.Vitamin D may help to prevent the onset of diabetes. "A study in Finland found children given a vitamin D supplement for several years had an 80 per cent reduced risk of developing Type I diabetes as young adults," says Dr Holick. A deficiency in vitamin D is also thought to contribute to Type II diabetes, according to a recent study by Dr Barbara Boucher at St Bartholomew's and the Royal London Hospitals.
  4. Beats SAD. Seasonal Affective Disorder (SAD) - or the winter blues - is a depression specifically caused by lack of sunlight. Lightboxes can be used to treat it, although increased exposure to natural sunlight is more beneficial. Get out for an hour's walk in the morning during autumn and winter months, and sit outside for 15 minutes a day in summer.
  5. Helps prevent MS. Multiple sclerosis (MS) is a disease of the central nervous system, leading to tremors and even paralysis. The cause is not known but scientists have noted that exposure to sunlight in childhood appears to dramatically reduce the risk of developing this disease in later life. Scientists have also noted that the incidence of MS is lower in sunnier countries.
  6. Prevents cavities. The sun could even help to keep your teeth strong. A dental study found the prevalence of cavities was greater in children from Scotland, the North-West, Wales and Merseyside - areas with less than average sunshine. The proportion of 12-year-olds with untreated cavities was three times greater in Scotland than in the South West Thames region.
  7. Relieves aches and pains. Being out in the sun helps to warm the body's muscles and eases stiffness, reducing the pain caused by inflammatory conditions such as arthritis.
  8. Reduces risk of cancers. Although over exposure to the sun increases your risk of skin cancer, vitamin D provided by sunlight can actually help to significantly reduce your risk of other types of cancer. A study carried out by the US National Cancer Institute found that people exposed to high levels of sunlight were significantly less likely to die from breast and colon cancer. A similar effect was seen in bladder, womb, oesophagus and stomach cancer.
  9. Boosts fertility. The sun reduces levels of the hormone melatonin which suppresses fertility, so it is more likely you'll conceive in summer. And sunlight not only makes you more fertile, it increases the length of your fertility. A study in Turkey discovered that women who get less than an hour of sunlight a week reach menopause seven to nine years earlier. Sunlight also boosts testosterone levels in men, which makes summer the perfect time for baby-making.
  10. Gives you more energy. Melatonin also regulates sleep, so having lower levels of this hormone in your body gives you more get up and go. This is why you need less sleep in summer but still feel livelier. Plus, being woken by natural light rather than an alarm clock helps you feel more positive.
  11. Eases IBD. People with Crohn's disease or other inflammatory bowel disorders (IBD) generally have low levels of vitamin D in their bodies, according to several studies. Sunlight is the best way to boost vitamin D in these cases. Although it is available in some foods (including meat, eggs, oily fish and some breakfast cereals), levels are low and poor absorption of fat - a common complication of inflammatory bowel disease - may make it difficult for sufferers to absorb vitamin D from their diet.
  12. Beats period problems. About one in five women of childbearing age suffer from polycystic ovary disease which causes abnormal periods, unwanted body hair and infertility. Half of 14 women treated with vitamin D and calcium by Dr Susan Thys-Jacobs at St Luke's-Roosevelt Hospital, Columbia University in New York, recovered normal periods and two became pregnant. Dr Thys-Jacobs also found that women with premenstrual syndrome are likely to be deficient in vitamin D.
  13. Helps skin conditions. Exposure to the sun can help to heal such skin conditions as psoriasis, acne and eczema. Regular controlled sun exposure is often prescribed for sufferers. For serious cases, contact your GP. For minor cases, try exposing affected areas of skin to the sun for up to 30 minutes before covering up or slapping on the sunscreen - but make sure you never burn.
  14. Boosts your immune system. Sunlight encourages the production of white blood cells, which help to boost your immune system and fight infection.
  15. Helps you lose weight. Higher levels of serotonin in our bodies not only makes you feel happy but it also suppresses the appetite, so you'll eat less in warmer weather.

System Description

A park bench will be modified to accommodate a sturdy sunshade mounted to the sides and back. The top of the sunshade “roof” will actually be an acrylic mirror, pivoted around a motorized horizontal hinge. The bench will also be pivoted, except it will pivot about a vertical rod, anchored to the ground at one end of the bench. The other end of the bench will roll in an arc around the pivot under motorized control. It may be more feasible to simply rotate the mirror support post. Either way the result will provide the mirror with 2 orthogonal axes of rotation. Smaller motors will control the angle of a solar-tracking solar cell which will charge a battery to run all the motors and the controller.

The Design Challenge controller(NXP  FRDM-KV31FFRDM-KV31F will be used as a system controller calculating positions controlling 4 motors and communicating via Bluetooth The Design Challenge motor and motor controller(NXP FRDM-MC-LVPMSM will be used to control one of the angular axes of the mirror probably using a lead screw The other mirror axis will also likely be driven with a lead screw This arrangement should allow the motors to be turned off when not needed without allowing back-drive rotation from the wind

The supplied motor requires 24 volts – this will be supplied either from a 24 volt battery or a 12 volt battery with a DC-DC boost power supply.

The battery will be charged by a solar-tracking solar cell, sized to supply enough power even under partly overcast conditions. In full overcast conditions, it may not be very useful to run the mirror. This solar cell will be mounted on a motorized 2-axis gimbal to allow it to independently track the sun. Alternatively it could be mounted perpendicular to the median input direction of the mirror to eliminate 2 motors. Unfortunately this method would not keep light exactly perpendicular to the solar cell, but it might be adequate. A complex gearing arrangement might help as the relationship between angle to the sun and mirror position could be “calculated” by a mechanical set of gears, or cams. This could be the real ingenious aspect of this project.

This project is physically large and requires significant resources to complete - if it works the result should be worth the time and expense.


This project aims to reduce the risks of slipping and falling on ice and snow on a dwelling walkway, as well as reduce the risks of injury from manually clearing snow. The plan is to harness the power of the sun to automatically melt and evaporate any snow and ice that accumulates on the walkway. This design challenge is a great additional motivation to contribute in some small way to improving the quality of life of seniors and reducing health care costs without increasing carbon footprint.


Next Steps

Hopefully the design challenge kit will arrive so I can do an unboxing video for my next blog, if not I will do show some more detail of the design.


Relevant Links

MLA Design Challenge


The full set of Clear Walk project blogs can be found here:

Make Life Accessible