FLEXIBLE & STRETCHABLE ELECTRONICS FOR BIOINTEGRATED DEVICES

Presented by :Nitin Kumar choukikerScholar no.-152126104

Introduction• Bio-integrated electronic devices act like an

interface between doctors and suffering patients.

• Develop high performance flexible and stretchableelectronic and optoelectronic devices using highquality single crystal inorganic materials.

• Apply these technologies for the health monitorand therapy systems.

Bendability & stretchability of inorganic electronic materials

• Inorganic materials such as silicon and metals are stiff and readily break when their intrinsic strain exceeds even very small values, such as 1 percent.

• Basic beam theory predicts that the bending-induced maximum strain of a membrane is proportional to the product of film thickness and bending curvature.

• If the maximum strain is limited to a critical strain to rupture of the material (1%), the maximum allowable bending curvature will be inversely proportional to the thickness of the membrane.

Ultrathin Flexible Silicons

300nm thick silicon ribbon

Stretchable Silicon:

Transfer Printing:•Form semiconductor nanomembranes ,

anchored at end points.

•Transfer them to a target substrate by printing.

•Interconnect to form integrated devices.

Transfer Printing:

Extreme bendability and flodability in Ultrathin circuit:

Strain= thickness bending radius

<1.7micro meter

plasticSi (p)

Si(n)Etch hole

sio2 metal

Bio-integrated devices in skin(epidermal):

• Electroencephalograph (EEG) measurements, based on epidermal electronic systems laminated on a human forehead in a manner much like a temporary transfer tattoo, mechanically invisible to the wearer.

• Attachment is enabled by van der Waals force without any conductive gels, these systems can function for more than two weeks at the exact same position without decomposition of the adhesives.

• Depending on where the electronic tattoo is placed, EEG, ECG measurements are possible with very high signal-to-noise ratio.

• In addition to electrophysiological sensing, studies have successfully demonstrated the monitoring of skin temperature, mechanical deformation (strain), mapping of brain activities.

Electroencephalography(Alpha rythms)• When large ensembles of neurons fire synchronously,

a large electricfield is generated and can be measured on the scalp, called electroencephalography(EEG).

• Alpha range neural activity(8-12hz) reflect the attention to visual environment.

• When subject gain visual attention focus, amplitude of alpha oscillation decreases(eye open), while amplitude of alpha oscillation increases by losing visual attention focus(eye close).

Epidermal Electronic System

Electronic chip on forehead:

Bio-integrated devices in brain:• Flexible brain-computer interfaces (fBCIs)

are microelectrode array fabricated on layers of polymers (e.g.polyimide).

• to record and process neuronal signaling pattern

• to use this data to control an external device. The increased bendability of these devices make them less harmful to brain tissues after immediate implantation .

Electronics devices integrated with brain:

Advantages:-•High resolution (50~150 micrometer

size, 2~10 mm length, ~500 micrometer spacing)

•Good SNR.

•Real time mapping.

•Pin point location.

Disadvantages:-•Deep penetration causes mechanical

tissue damage .

• Activate immune functions of brain causes deposition of inflammatory tissues on electrodes. (after 3~6 months)

•Difficult long time mapping.

Thank you