Data worth digesting
A new development could allow patients with ulcers and digestive troubles to avoid very unpleasant procedures. Tom Shelley reports
A brother-and-sister team from Iran have come up with a pill that delivers continuous information about acidity in the gastrointestinal tract, yet should cost no more than £4 each.
Unlike the sophisticated Japanese Norika 3 pill sensor described in Eureka’s September 2003 edition – which included lights and a camera, and about which little has been heard since – the device devised by Amir Jalali Nejad and his sister Hoda Jalali Nejad sounds like something we might be swallowing quite soon.
The breakthrough idea is to make use of the fact that acrylic acid co iso octylacrylate swells in acid solutions and contracts in less acid solutions. Within it are what appear to be two, etched flat, ferromagnetic elements the developers describe as ‘coils’.
At the recent British Invention Show in London, Ms Jalali Nejad revealed that the device exists as a prototype and has so far been trialled in animals and also in a human patient who was brain-dead. The device, she added, was powered externally by acoustic waves and the changes in the dimensions of the sensor altered the resonant frequency of the two coils inside. This change could then be picked up and used to calculate the pH.
The idea was inspired by the problems encountered by their elderly grandfather when having to suffer the effects of undergoing conventional endoscopy.
The intention of the design is to provide useful information, while avoiding some of the problems that have prevented the deployment of other swallowed sensing devices. Battery powered devices are, in their opinion, to be avoided because of possible “disruption of the monitor integrity permitting toxic leaks from the electronic components or battery into the gastrointestinal tract”.
Some of the schemes being developed in Europe actually contain small motors, so they can move around under their own power, making them worryingly large. The Iranians, on the other hand, believe that the devices need to be very small.
“A large pill could encounter a structure or acute intestinal angulation during transmit of the small bowel,” says Ms Jalali Nejad – possibly resulting in it becoming lodged there. The other requirement is that the devices should be cheap to make, sterilisable, disposable and very reliable.
This means that the devices have to be passive, which they are, yet respond to an input signal in the form of a pulse train to excite the sensor coils, which then produce a decaying response at a resonant frequency decided by their spacing. The signal is produced and detected by a unit worn on the patient’s chest.
The technology is being developed as a private venture, although it has the support of the First Institute of Inventors and Innovators of the Islamic Republic of Iran.
* Devices are low-cost passive sensors that can be swallowed
* Made of polymer that changes in dimensions under different pH conditions, they are designed to oscillate at a resonant frequency that depends on pH
* The sensors are excited externally, and signals are received and analysed by the same device
More information: Email Hoda Jalali Nejad and British Invention Show
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