Ultrasound neuromodulation has recently been used in clinical trials to treat conditions such as epilepsy. The underlying mechanism of action of ultrasound on neurons has not been very well understood. We present a mathematical model that describes the effects of ultrasound on neurons and experimentally verify the predictions using novel high-speed digital holographic imaging and electrophysiology.

doi: https://doi.org/10.1101/2021.06.11.447976

The COVID-19 pandemic has exposed the vulnerabilities of healthcare systems worldwide. Access to afforddable and on-demand ventilation systems emerged as a clinical need during this time. MADVent is a low-cost (<$500) ventilation system that can be assembled in < 15 minutes.

Vasan, Aditya, et al. “MADVent: A low‐cost ventilator for patients with COVID‐19.” Medical devices & sensors 3.4 (2020): e10106.

Transmitting acoustic fields in to enclosed cavities such as the skull for ultrasonic neuromodulation could result in the formation of standing waves, and thus, regions of extremely high or low intensity. We borrow from architectural acoustic principles to develop microscale diffusers that are integrated on the transducer face.

Microscale concert hall acoustics for uniform ultrasound stimulation

Although optogenetics has revolutionized our understanding of neural circuits and disease states, it is limited by the depth of penetration of light in tissue. We have developed sonogenetics, a non-invasive technique that uses a combination of ultrasound and proteins that we have discovered to be ultrasound-sensitive.

Duque, Marc, et al. “Targeted millisecond-scale activation of cells using non-invasive Sonogenetics.” bioRxiv (2020).

The development of diagnostics and medical devices has historically been concentrated in high-income countries, despite a significant need to expand healthcare services to lowand middle-income countries (LMIC). This paper reviews diseases and conditions that have not received much attention in the past despite imposing a significant burden on healthcare systems in these circumstances.

Vasan, Aditya, and James Friend. “Medical Devices for Low-and Middle-Income Countries: A Review and Directions for Development.” Journal of medical devices 14.1 (2020).

We present techniques to fabricate and characterize simple thickness mode piezoelectric devices using lithium niobate (LN). Such devices have been shown to atomize liquid more efficiently, in terms of flow rate per power input, than those that rely on Rayleigh waves and other modes of vibration in LN or lead zirconate titanate (PZT).

Vasan, Aditya, William Connacher, and James Friend. “Fabrication and Characterization of Thickness Mode Piezoelectric Devices for Atomization and Acoustofluidics.” JoVE (Journal of Visualized Experiments) 162 (2020): e61015.

Intra-ocular pressure (IOP) is one of the key determinants of glaucoma. The gold-standard technique to measure IOP is by contact tonometry. We developed a pressure sensor that can be implanted in the cornea for long-term, optical measurements of IOP based on interferometry.

Phan, Alex, et al. “Investigation of long term drift of an intraocular pressure sensor.” Microsystem Technologies (2021): 1-7.

Three-dimensional cell agglomerates, such as organoids, are broadly useful in tissue engineering and drug testing. We report a well-free method to form large (1-mm) multicellular organoids using 100-MHz surface acoustic waves (SAW) without direct contact with the media or cells. Calcium ion signaling through these clusters suggests a continuous tissue construct: an organoid. They may be formed at will, and the method is feasibly useful for formation of numerous organoids in a single petri dish.

In preparation

Confirm Rx is the worlds first smartphone compatible insertable cardiac mornitor. The device is implanted using a quick, minimally-invasive procedure and transmits data using low-energy Bluetooth technology.

Ip, John, et al. “Accuracy of arrhythmia detection in implantable cardiac monitors: A prospective randomized clinical trial comparing Reveal LINQ and Confirm Rx.” Pacing and Clinical Electrophysiology 43.11 (2020): 1344-1350.

Meta’s Reality Labs is developing the next generation of human computer interaction systems, with an emphasis on wrist-based EMG. A key step in making this a reality is understanding and deriving relationships between the biomechanics of the hand and EMG signals produced during movement. I spent a few months working as a research intern on this problem designing and fabricating instrumentation, analyzing physiologic and mechanical factors related to hand movement and assessing relationships with EMG signals.

Advanced in the field of ultrasound-based cellular stimulation and sonogenetics rely on transducers that are specifically made for cellular stimulation. We describe the development of devices that weigh less than a gram, capable of high pressure output, without significant temperature changes.

In preparation

I try to support students in underrepresented communities through initiatives both on and off campus: by representing UCSD at the AAAS advocacy workshop on capitol hill, for refugee youth through the international rescue committee, college students through the MAE graduate women’s group and the ENLACE program, and junior graduate students with DACA status in our lab.