MED­I­CAL IM­PLANT TECH­NOL­OGY

From the hum­ble be­gin­nings of the car­diac pace­maker, med­i­cal im­plants have evolved into so­phis­ti­cated de­vices ca­pa­ble of re­cip­ro­cal in­ter­ac­tion with the sys­tems they ma­nip­u­late. For the re­la­tion­ship be­tween hu­man bod­ies and tech­nol­ogy, the pos­si­bil­i­ties a

Popular Mechanics (South Africa) - - Front Page - BY MEGAN BAN­NER

Cy­borg’ i s some­thing of an evoca­tive con­cept, con­jur­ing im­ages of fu­tur­is­tic space war­riors with me­chan­i­cal ex­oskele­tons, or cack­ling su­pervil­lains who shoot laser beams from their eyes. The word, in fact, is short for ‘cy­ber­netic or­gan­ism’ – any liv­ing crea­ture with mecha­tronic com­po­nents.

Even more broadly, it’s a re­la­tion­ship be­tween an or­gan­ism and tech­nol­ogy. So while, yes, space war­riors and su­pervil­lains may be cyborgs, by these def­i­ni­tions, there are also many more re­al­is­tic ex­am­ples of cy­borg tech­nol­ogy all around us. Medicine is an ob­vi­ous ap­pli­ca­tion, and cur­rent tech­nol­ogy has one of two func­tions: to re­store, or to en­hance.

Restora­tive cy­borg tech re­pairs bod­ily struc­tures or pro­cesses that are bro­ken or ab­sent to re­store an av­er­age level of func­tion.

En­hance­ment tech­nol­ogy, on the other hand, is the stuff of our fan­tasies: in­ter­ven­ing to op­ti­mise per­for­mance or gain brand new func­tion in what was, maybe, al­ready a per­fectly func­tional or­gan­ism.

While many in­no­va­tions al­ready ex­ist to en­hance hu­man per­for­mance, for the most part, main­stream medicine still fo­cuses on restora­tive tech­nolo­gies through the in­stal­la­tion of in­creas­ingly so­phis­ti­cated im­plants. Here we look at a few im­plant de­vices: the fas­ci­nat­ing, the com­mon, and the rev­o­lu­tion­ary.

While you may not self­i­den­tify as a cy­borg be­cause of your car­diac pace­maker (and that’s just fine), I’d ar­gue that any in­te­grated im­plant that re­sponds to feed­back from your body, does, tech­ni­cally, give you cy­borg brag­ging rights.

COCHLEAR OCHLEAR IM­PLANTS

The cochlea in the in­ner ear is the or­gan of hear­ing in hu­mans. Sound waves en­ter the ear, are am­pli­fied by the ear drum, and then hit sen­si­tive hairs in the cochlea that then send elec­tri­cal sig­nals to the brain.

For most deaf peo­ple, the hear­ing nerve that trans­mits the elec­tric sig­nal to the brain is in­tact, but the tiny hairs of the cochlea are dam­aged or miss­ing.

A cochlear im­plant is a sys­tem that pro­vides an en­tirely new mech­a­nism for hear­ing. A mi­cro­phone near the ear re­ceives sound sig­nals, and then a small ex­ter­nal pro­ces­sor con­verts the sounds to dig­i­tal in­for­ma­tion. This dig­i­tal in­for­ma­tion is trans­mit­ted by an an­tenna to the part of the sys­tem that is sur­gi­cally im­planted un­der the skull. skull When the im­plant re­ceives in­for­ma­tion from the pro­ces­sor, it sends elec­tric sig­nals down to an elec­tri­cal ar­ray in­serted in the cochlea. This stim­u­lates the au­di­tory nerve di­rectly, send­ing sound in­for­ma­tion to the brain. The cochlear im­plant re­stores hear­ing by us­ing sim­ple tech­nol­ogy to by­pass the dam­aged in­ner ear and in­ter­act di­rectly with the func­tional parts of the re­cip­i­ent’s hear­ing mech­a­nisms. These ‘ bionic ears’ have been avail­able since the 1980s, and more than 300 000 have been im­planted world­wide.

IM­PLANTABLE CAN­CER VAC­CINE

This one is not a me­chan­i­cal de­vice, and it’s not de­signed to re­store lost func­tion, but it is still an in­no­va­tive, po­ten­tially rev­o­lu­tion­ary med­i­cal im­plant. A bio­ma­te­rial-based can­cer vac­cine has been de­vel­oped at Har­vard Univer­sity, util­is­ing im­munother­apy tech­nol­ogy to stim­u­late the body’s own im­mune sys­tem to fight tu­mours. One rea­son tu­mours are so harm­ful is be­cause they are made from our body’s own cells, so they are typ­i­cally not recog­nised as danger­ous or for­eign by our im­mune sys­tem.

The im­plant is roughly the size of a Panado tablet. It is made from a biodegrad­able scaf­fold­ing that is in­fused with anti­gens (par­ti­cles that in­duce an im­mune re­sponse) from the pa­tient’s own tu­mour cells, as well as spe­cial stim­u­la­tors that at­tract and ac­ti­vate im­mune- sys­tem cells called den­dritic cells. The den­dritic cells pick up pieces of the tu­mour anti­gens from the im­plant and carry them to the lymph nodes, the ‘com­mand cen­tres’ of the im­mune sys­tem. The im­plant es­sen­tially teaches the body that the tu­mour is a for­eign ob­ject that must be elim­i­nated. In on­go­ing clin­i­cal tri­als, sci­en­tists have demon­strated that the im­plant can shrink or erad­i­cate mul­ti­ple types of tu­mours, and it also shows prom­ise in long-term pro­tec­tion against tu­mour re­cur­rence. Just as with a dis­ease such as chicken pox, when the body comes into con­tact with an anti­gen it has seen be­fore, it springs into ac­tion to im­me­di­ately de­stroy the threat.

DEEP BRAIN STIM­U­LA­TION

Neu­ral im­plants in­clude any­thing that in­ter­acts with the elec­tri­cal path­ways of your own ner­vous sys­tem. Cochlear im­plants are one ex­am­ple, and an­other is a di­rect brain im­plant that pro­vides deep brain stim­u­la­tion to re­lieve the symp­toms of Parkin­son’s dis­ease.

While it sounds like a par­tic­u­larly sat­is­fy­ing mas­sage tech­nique, deep brain stim­u­la­tion is more akin to a ‘ brain pace­maker’ of sorts. Elec­trodes are sur­gi­cally im­planted in the brain through the top of the skull, and con­nected by wires run­ning un­der the skin down to a bat­tery-pow­ered stim­u­la­tor im­planted into the chest. The stim­u­la­tor sends elec­tri­cal pulses through the leads to block the faulty sig­nals which, in Parkin­son’s pa­tients, would oth­er­wise cause tre­mors, rigid­ity and slow­ness.

This tech­nol­ogy has been around for a cou­ple of decades, and it re­duces symp­toms in most re­cip­i­ents. How­ever, there are cer­tain lim­i­ta­tions that new tech­nol­ogy is just be­gin­ning to ad­dress. Ear­lier this year, re­searchers re­vealed an ‘adapt­able’ deep-brain- stim­u­la­tion im­plant. Rather than the de­vice be­ing pro­grammed ex­ter­nally by a doc­tor, this new im­plant can read and re­spond to sig­nals from the brain by it­self. This closed-loop sys­tem fine-tunes it­self to de­liver the ex­act level of stim­u­la­tion needed to block faulty sig­nals. This ex­tends the bat­tery life of the de­vice, be­cause it is no longer al­ways fir­ing at max­i­mum ca­pac­ity, de­lay­ing in­va­sive re­place­ment surgery down the line.

It also min­imises the in­vol­un­tary move­ments of­ten caused by over­stim­u­la­tion, and is as ef­fec­tive as tra­di­tional deep brain stim­u­la­tion at con­trol­ling tre­mors and stiff­ness. The tech­nol­ogy em­pow­ers pa­tients to re­gain phys­i­cal abil­ity and a bet­ter qual­ity of life.

Trans­mit­ter Speech pro­ces­sor Re­ceiver/ stim­u­la­tor Mi­cro­phone Elec­trode ar­ray EAR WITH COCHLEAR I MPLANTABOVE: The cochlear im­plant by­passes a dam­aged in­ner ear to re­store hear­ing through di­rect stim­u­la­tion of the au­di­tory nerve.

ABOVE: Bat­tery-pow­ered elec­trodes stim­u­late par­tic­u­lar parts of the brain to re­duce symp­toms in peo­ple with Parkin­son’s Dis­ease and other neu­ro­log­i­cal dis­or­ders.

ABOVE: Tablet-sized im­plants teach the im­mune sys­tem to recog­nise can­cer­ous tu­mours as a danger­ous for­eign ob­ject. DEEP BRAIN STIM­U­LA­TION Lead Skull Lead wire Brain Brain Ex­ten­sion Elec­trode Subtha­la­mic Nu­cleus Neu­rostim­u­la­tor

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