Sunday 23 September 2012

Batteryless sensing medical computers in our clothes

Using our washing machine to clean and charge up our clothes 
Design by Lyndsay Williams 

The future of clothing and wearable computer  technology will include clothes with invisible  inbuilt medical, sports and wellbeing sensors embedded  into the fabric.

Computer rendering of future sensor - sensing shirt button

We may want  smart sensing to be embedded in our clothing including shoes,  that can measure biomedical parameters , e.g. motion, body temperature and  transmit this data  via radio to the mobile phone for healthcare applications.
Health applications also include fall detection for people living alone but nobody wants cumbersome pendants as used as present.

 The clothes must also be  washable (up to 90C) and preferably have no battery, as batteries do not cope with  the temperature range in a hot wash.

We also want our clothes to light up for decoration and for safety, we can also have them emit relaxing signals if it detects we are stressed. We might want them to talk to our smartphones for 24/7 medical care.

Here is an example of a sensing light up cycle jacket which uses sensors to indicate movement and cyclist turning left and right.

We want tiny sensors no larger than a shirt button so as to be unobtrusive. Where can we get these from?

There is a established  area of the consumer market in Tyre Pressure Monitoring Systems TPMS  which can  provide a solution to sensors for clothing. From Nov 2012 all new UK cars will require TPMS. This allows more  safety, re braking,  longer life tyres  and better fuel economy. There will be millions of these low costs sensors so we can re purpose  them.  These sensing semiconductors provide pressure measurement, acceleration in 2 dimensions, temperature, microcontroller,  complete with a 315MHz radio transmitter. Here are some examples,  from Texas Instruments 

Texas Sensor more here.

and Melexis below, radio transmitter not shown 

There are other manufacturers of  TPMS sensors and they cost less than  £5 for one off.

These TPMS sensors  can be re purposed for clothing sensors, and are washable up to 150C.

 However there is still the problem of batteries,  changing them and making them  waterproof.  It  is preferred  to use power harvesting rather than Lithium cells. All clothes need to be washed, we use a washing machine. The spin cycle provides a large amount of vibration (particularly if load unbalanced) and energy, some via centrifugal force  for power harvesting, here is some research on using the motion of a car wheel to charge up the TPMS. Piezo sensors are a possibility as here.  There is also the possibility of using the varying electromagnetic forces inside the drum from the washer motor. This system  needs further research to see how much power can be derived from a normal spin cycle e.g.  4 mins at 900 RPM. An Aerogel SuperCapacitor can be charged in this period of time. These capacitors operate up to 70C.

Image of Bosch Washer from John Lewis

The TPMS semiconductors can have a shock survival of up to 4000G.

This prototype design  will enable our clothes to have built in sensors, lights and just a normal wash cycle with spin to charge up the clothes every few days.

Rendering of Girton Labs HexSensor size 10 x 10 mm

There are other advantages to embedding sensors into our clothes, an ID tag, with radio transmitter so we don't loose them, and when clothes put in washing machine the care tag data is transmitted to washer for correct wash, at the correct temperature so no more mixing of whites and coloured. The clothes can transmit a signal when due for a wash or record in a database the last time clothes were one. Some people do not like to be seen in the same outfit twice so a date log of wearing the clothes sent to mobile phone with help the fashion conscious!

Additional areas to research, using the TPMS  pressure sensors to monitor pressure points on the body, power requirements etc.

We can maybe also use these tiny sensors to track our glasses which can get lost...


  Girton Labs in conjunction with Northumbria University had already built  proof of concept designs for early onset epilepsy detection using accelerometers, and work is in progress with Smart Sensing Bandages for healthcare.

Contact Lyndsay Williams, Girton Labs, Cambridge, UK +44 (0) 7970 101578

2012 Girton Labs designs, click to enlarge


  1. Thanks for info. I am glad to be a part of your post.
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  2. Your information on advance medical techs are thought-provoking, interesting and well-written Lyndsay. Thank you for sharing.
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