Department of Neuroscience and Biomedical Engineering

Medical Ultrasonics Laboratory (MEDUSA)

The main research goal of MEDUSA is to create novel technologies exploiting non-linear ultrasonics for therapeutic or diagnostic purposes.

Ultrasound provides unconventional approaches to manipulate material from micro-scale, e.g. drug carriers or cells, to macro-scale, e.g. tissue or organs. Ultrasound can be used create force fields through the skin, in a non-destructive manner, to influence targets inside the body from a distance. This allows one to develop non-invasive applications and technologies for advanced medical diagnostics and interventions. Ultrasound can also add value to small minimally invasive medical instruments by activating them based on non-linear ultrasound approaches. Our research has recently contributed to establishing several medical technology companies.

Our current interests include e.g. ultrasound-enhanced fine-needle biopsy (USeFNB), ultrasound-enhanced medical needles, ultrasonic scalpels, ultrasonic drug delivery, and ultrasonic gene transfection. We also conduct basic research on acoustic phenomena that have the potential to be translated to medical applications in the future.
MEDUSA

We have multi-national multi-disciplinary team with expertise in physics, biomedical engineering, electrical engineering, acoustics, medicine and business. 

The laboratory is headed by Prof. Heikki Nieminen.

Recent news

The ultrasonic needle, which is a regular medical needle with a metal attachement connected to a large box on the side of the syringe

21st century medical needles for high-tech cancer diagnostics

Modern medicine needs better quality samples than traditional biopsy needles can provide, ultrasonically oscillating needles can improve treatment and reduce discomfort

News

Recent research

Ultrasound-enhanced fine-needle aspiration biopsy (USeFNAB)

Fine-needle biopsy is a common medical procedure for obtaining a tissue sample for diagnostic purpose. This procedure, broadly used in cancer detection, suffers from obtaining and inadequate sample up to 30% of cases.

We are developing a new method, USeFNB, in which ultrasound is used to actuate the very tip of the needle (Perra et al. Scientific Reports. 2021;11:8234; Le Bourlout et al. IEEE IUS 2020). The non-linear interactions of the needle tip and tissue lead to increase in the amount of tissue by 3-5x compared to fine-needle aspiration biopsy (FNAB) using the same needle. The improvement in tissue quantity is demonstrated in the Figure 1. Importantly, the obtained tissue mass increases, while no major effect on sample quality, as demonstrated by histological assessment. The feasibility of the USeFNAB method has been demonstrated recently (Perra et al. 2021) as summarized in the following:

 

USeFNAB

The comparison of the FNAB and USeFNAB procedures with typical tissue mass obtained are exemplified in the following video:

We have further developed the power efficiency of USeFNAB concept to potentially allow batterization of USeFNAB in the future (Le Bourlout et al. 2020). Following optimization, we have reached an electrical-to-acoustic power -efficiency of up to 69%. This result suggests that the developed waveguide structure allows to drive the system with low power electronics permitting miniaturization and portability of the USeFNAB device.

USeFNAB

Ultrasound-enhanced medical needle (USeMN)

USeMN could have several potential applications in the future, beyond USeFNAB. Inside liquid, an ultrasonically actuated medical needle can be made to vibrate rapidly producing cavitation bubbles. These bubbles grow and can collapse rapidly. We have recorded accelerations of bubble-water boundary of up to 20 000 G (Perra et al. 2021). With further advancements of the cavitation events localized near the tip of the medical needle could be used for fractionate tissue (histotripsy) such as tumors or even enhance drug delivery by improving tissue permeability. Importantly, the cavitation can be made to exhibit only at the tip of the needle providing predictability to the spatial location of cavitation and, therefore, allows the control safety aspects associated with cavitation. The following high-speed video exemplifies cavitation events at 33 kHz observed near the tip of a USeMN:

While the USeMD is embedded in air, liquid delivered to a tip of a USeMN can be atomized to small droplets using capillary waves delivered to the needle tip (Perra et al. 2021). This approach could be used to deliver and disperse drugs on tissue surfaces within gas-filled bodily cavities, e.g. in the respiratory system. Importantly, we demonstrated that the droplet size can be controlled by the selection of the ultrasound frequency (Perra et al. 2021). Atomization of water at 33 kHz is exemplified in the following high-speed video:

We have also demonstrated that the USeMN is capable of transporting microparticles (Perra et al. 2021). This could be advantageous in various drug and gene delivery applications, since the approach could contribute to the delivery beyond the reach of a traditional needle. The transport of microparticles by 33 kHz ultrasound inside water is demonstrated in the following:

Ultrasonically actuated scalpels

Ultrasonic scalpels are known for their capability of cutting tissue. Usually such technologies employ actuation along the longitudinal axis of the blade. However, transversely oscillating motion has received less attention. In this study, our objective is to broaden understanding of the behaviour of different wave modes emitted from a transversely oscillating scalpel blade, modelled as a wedge embedded in viscoelastic material representing soft tissue. Our simulations demonstrate the different wave modes emitted from the needle. The following 2D velocity surface map shows the vibrating wedge oscillating at 30 kHz on the surface of viscoelastic medium representing soft tissue, captured at a time step 0.66 ms. The x and y components of velocity (m/s) are shown respectively on the left and right:

Wave propagation in a media due to ultrasound

Ultrasonic levitation of particles

Ultrasound can be used to levitate and trap small particles. This approach allows one to manipulate and sort small objects, such as micro-spheres and cells, without touching them. The following example demonstrates how micro-spheres are trapped inside liquid along the axis of the ultrasound propagation as well as along the axis perpendicular to the ultrasound propagation:

Ultrasonic levitation of particles

Publications

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