IEEE Spectrum June, 2015 - 73

PaRt 3: Changing the Code

imPlants

The Ultimate
Cyborg Patient
M o d e r n M e d i c i n e offers a multitude of ways to go

bionic: Today's implanted electrical devices can stimulate
the nervous system, restore the senses, deliver drugs, and
may soon replace entire organs. Here's a sampling of cyborg
technologies that benefit from advances in processing power,
batteries, and sensors, which allow these devices to adapt
therapies on the fly. -Sarah Lewin

he says this approach, which minimizes the cost and maximizes the ease
of manufacturing, could be powerful.
"The typical idea has been that you
have one device that you guide precisely [to perform a] surgical procedure," Gracias says. His strategy
borrows a page from the imperfect
world of biology: "If you have a large
number of not-perfect devices, you
may be able to achieve the same functionality as one perfect one."
the gastroIntestInal tract Is

Brain

DoCtoRs already use deep brain stimulators
to quiet Parkinson's tremors and are
investigating their application for depression
and other disorders. A new implant from
Medtronic, the Activa PC+S, may yield
fresh insights. When not generating
impulses, this implant records brain signals,
providing information that may help doctors
understand how neurological diseases arise.
status: In testing, approved in Europe

eyes

st. JuDe MeDiCal's latest neurostimulator,

the Protégé, sends electric pulses to the
spinal cord to interrupt signals that cause
chronic pain. It's the first such device
built for upgrades, so new software
can be added as researchers develop
new therapies.
status: On the market

limBs

with Cuff eleCtRoDes around nerve

to RestoRe sight to the blind, the Argus II

from Second Sight captures images with
a video camera and stimulates the retina
with 60 tiny electrodes, allowing patients
to discern shapes and movement. It's
intended for people with diseases that
cause photoreceptor cells to degenerate.
status: On the market

spine

bundles in their arms, amputees gain
feeling from sensors in their prosthetic
hands. Researchers at Case Western
Reserve University and the Louis Stokes
Cleveland Veterans Affairs Medical Center
are developing a system that turns sensor
information into stimulation patterns, which
travel up the nerves to the brain.
status: Experimental

ears

the next-geneRation cochlear implant

may be the fully implantable device from
MIT's Microsystems Technology Laboratory,
which does away with external microphones
and power sources. It captures sound with
a piezoelectric sensor that detects the
middle ear's natural vibrations, then
stimulates the auditory nerve.
status: Experimental

heart

until now, virtually all artificial

hearts have been used to pump
blood only while patients with
heart failure wait in the hospital for
transplants. But soon, patients could go
home with the new heart from Carmat,
which is intended to last for years and
uses a microprocessor and sensors.
status: In testing
illustRation by

bryan christie Design

Bladder

on-the-MaRket implants treat

incontinence by stimulating the sacral
nerve to improve bladder control. At the U.S.
Department of Veterans Affairs' Advanced
Platform Technology Center, researchers
are developing an implanted pressure
sensor for the bladder that will trigger the
stimulator.
status: Experimental

o va r i e s

MiCRoChips bioteCh's drug-delivery chip
will release tiny amounts of a birth-control
hormone every day for up to 16 years when
implanted under a woman's skin-and
can be turned off via remote control if she
wants to get pregnant.
status: In testing

a fairly forgiving place to work
inside the human body. It's relatively
large and easy to access externally, and
it automatically funnels objects
through the body. Exploring trickier
locations, such as the eye, the brain,
and the bloodstream, will likely require
more sophisticated microrobot designs.
O ne sig n i f ic a nt hu rd le i s t he
machines' potential to trigger clots.
"When you talk to clinicians, one
thing that makes them go white and
never want to talk to you again is any
kind of notion of putting something
solid in the bloodstream," says John
Rogers, a pioneer of soft electronics for the body at the University of
Illinois at Urbana-Champaign. "There
are just really serious consequences
of any kind of structure that's freefloating and just traveling around."
[For more about Rogers and his
work, see "Giving Your Body a 'Check
Engine' Light," in this issue.]
Precise placement of microbots
is therefore crucial. Even the most
sophisticated microswimmers, ones
capable of following a change in pH
or temperature, might not be able to
combat the powerful currents in the
bloodstream. "The reality is, these
things are not going to swim for long
distances in your body," says ETH
Zurich's Nelson. An autonomous
swimmer might be able to muster only
north american

jun 2015

Table of Contents for the Digital Edition of IEEE Spectrum June, 2015