Rodrigo Aviles-Espinosa

• PhD in Photonics
• Senior Lecturer at University of Sussex

In this paper, the design and experimental evaluation of a parallel robotic system based on a linear delta geometry is presented. The design considers the requirements for high-precision applications including workspace, motion resolution, and payload. The entire design process includes robot kinematics, control, and optimization, resulting in the...

The development of future surgical therapies has driven the efforts to increase the precision of robot-guided manipulators beyond sub-millimetre accuracies. Medical applications such as reconstructive microsurgery, vitreoretinal eye surgery and cellular level neurosurgery still require achieving precision comparable to the size of human cells [1]....

In bio-signal denoising, current methods reported in the literature consider purely simulated environments, requiring high computational powers and signal processing algorithms that may introduce signal distortion. To achieve an efficient noise reduction, such methods require previous knowledge of the noise signals or to have certain periodicity an...

Background Reducing the global new-born mortality is a paramount challenge for humanity. There are approximately 786,323 live births in the UK each year according to the office for National Statistics; around 10% of these newborn infants require assistance during this transition after birth. Each year around, globally around 2.5 million newborns di...

A field-programmable gate array (FPGA) based system for digital filtering in a neonatal heart rate monitoring system is presented. The system employs electric potential sensors (EPS) and contains a single hardware filter stage for antialiasing. The remaining digital signal processing required to provide a clinical standard electrocardiogram (ECG) i...

Droplet transmission is the main route of spreading viruses such as COVID-19, wearing a mask serves as a crucial preventive measure to contain its spread [1]. Most of these masks are made of woven and non-woven fabrics [2], which are also meant to be re-used when properly sanitized [1]. The choice of materials varies from manufacturer to manufactur...

Magnetic miniature robots are controllable devices that can access complex and narrow regions of the human body in a minimal invasive manner in cavities such as the gastrointestinal tract or vasculature, with the potential to perform targeted delivery of therapeutic substances. These devices, are capable of being actuated near the target position f...

Heart rate monitoring is the predominant quantitative health indicator of a newborn in the delivery room. A rapid and accurate heart rate measurement is vital during the first minutes after birth. Clinical recommendations suggest that electrocardiogram (ECG) monitoring should be widely adopted in the neonatal intensive care unit to reduce infant mo...

This study aims to prepare, optimize, and characterize magnetic-field-sensitive sugar-templated polydimethylsiloxane (PDMS) sponges for localized delivery of an anticancer drug, 5-fluorouracil (FLU). For this purpose, different concentrations of carbonyl iron (CI) and magnetite Fe3O4 nanopowders were embedded as magnetosensitive materials in PDMS r...

Background Detecting neonatal heart rate rapidly and accurately at birth is essential if resuscitation is required. The Neo-Sense prototype provides a quick, non-invasive method to measure neonatal heart rate at birth based on electric potential sensing technology. The study aimed to inform the prototype design process by exploring the required fea...

With the growing demand for personalized medicine and medical devices, the impact of on-demand triggerable (e.g., via magnetic fields) drug delivery systems increased significantly in recent years. The three-dimensional (3D) printing technology has already been applied in the development of personalized dosage forms because of its high-precision an...

Background: Around 10% of newborn infants require assistance during transition after birth. Heart rate (HR) is the most important clinical indicator to evaluate the clinical status of a newborn. Aim: Our study aimed to review all established and novel methods to detect HR in babies giving special consideration to non-invasive techniques. Method...

ABSTRACT Balloon aortic valvuloplasty (BAV) has been employed as a simple and low-cost treatment method for patients with severe aortic stenosis, for symptom palliation in patients considered inoperable, for aortic valve replacement and to select the proper transcatheter heart valve (THV) size. During THV implantation choosing the correct balloon s...

In this letter, we report the early detection of fetal cardiac electrical activity recorded from the maternal abdomen non-invasively. We developed a portable and non-invasive, prototype based on electric potential sensing technology to monitor both: the mother and fetal heart activity during pregnancy. In this proof of principle demonstration, we s...

In this paper we report a novel biosensor based on electric field detection for recording cardiac electrical activity in zebrafish embryos. Using Sussex patented Electric Potential Sensing technology, a portable, non-invasive and cost-effective platform is developed to monitor in vivo electrocardiogram activity from the zebrafish heart. Cardiac act...

In this paper we report the development of a Micro-electroscope, a multimodal approach that allows recording the morphological evolution occurring within the developing heart of zebrafish embryos while simultaneously recording its functional counterpart: in vivo non-invasive heart electrical activity.

Currently, there is no effective sensing technology available to monitor the electrocardiogram activity of the living zebrafish heart during early developmental stages. Most of the methods are based either on the use of simple visual inspections which are limited to quantifying the heart rate or invasive methodologies which require the insertion of...

The characterization of the electrocardiographic activity of the living zebrafish heart during early developmental stages is a challenging task. Most of the available techniques are limited to heartbeat rate quantification being this inaccurate. Other invasive methodologies require the insertion of electrodes noise isolated environments and advance...

In this letter, we report the continuous detection of the cardiac electrical activity in embryonic zebrafish using a non-invasive approach. We present a portable and cost-effective platform based on the electric potential sensing technology, to monitor in vivo electrocardiogram activity from the zebrafish heart. This proof of principle demonstratio...

We developed a low-cost, low-noise, tunable, high-peak-power, ultrafast laser system based on a SESAM-modelocked, solid-state Yb tungstate laser plus spectral broadening via a microstructured fiber followed by pulse compression. The spectral selection, tuning, and pulse compression are performed with a simple prism compressor. The output pulses are...

We developed a low-cost, low-noise, tunable, high-peak-power, ultrafast laser system based on a SESAM-modelocked, solid-state Yb tungstate laser plus spectral broadening via a microstructured fiber followed by pulse compression. The spectral selection, tuning, and pulse compression are performed with a simple prism compressor. The output pulses are...

Acquisition of images deep inside large samples is one of the most demanded improvements that current biology applications ask for. Absorption, scattering and optical aberrations are the main difficulties encountered in these types of samples. Adaptive optics has been imported form astronomy to deal with the optical aberrations induced by the sampl...

We have developed adaptive optics devices for laser scanning microscopy using liquid crystals. This device correct aberration occurs due to deep observation. In our system, a point light source is generated inside specimen. A detected wavefront error is fed back to the liquid crystal adaptive optics device simply placed to a bottom of objective len...

Yb-doped lasers [1] offer ultrashort pulses with high power and direct diode pumping. Their limited tunability can be addressed with nonlinear fiber broadening [2] and pulse compression. Laser wavelengths around 1 μm produce less absorption and scattering in biomedical tissue and it is near the two-photon excited fluorescent peak of GFP [3].

In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chir...

The requirement of less-expensive laser system for nonlinear bio-imaging applications can be addressed employing chip-sized devices. Preliminary studies using an amplified quantum-dot laser system show its potential to be used for such applications.

In the study of biological systems – cell biology being the premier example – nonlinear microscopy techniques are highly regarded for their ability to focus tightly on minute parts of a structure. Two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) microscopy, in particular, have overtaken even such stalwart techniques as co...

KEY WORDS: Nonlinear microscopy, Biological imaging, Adaptive optics 1. ABSTRACT Adaptive optics (AO) was developed to restore the performance of optical systems (i.e. astronomical telescopes) affected by distortions produced to light as it travels through inhomogeneous media. This is carried out by measuring the distorted wavefront (WF) and then c...

KEY WORDS: Nonlinear microscopy, semiconductor lasers and optical amplifiers. 1. ABSTRACT Two-photon excited fluorescence (TPEF) microscopy requires the use of high peak power laser systems to enable the generation of nonlinear optical effects as the light interacts with the specimen. At present, most ultra-short pulsed laser systems used for this...

KEY WORDS: Nonlinear microscopy, Biological imaging, Adaptive optics 1. ABSTRACT Adaptive optics (AO) was developed to restore the performance of optical systems (i.e. astronomical telescopes) affected by distortions produced to light as it travels through inhomogeneous media. This is carried out by measuring the distorted wavefront (WF) and then c...

The performance of imaging devices such as linear and nonlinear microscopes (NLM) can be limited by the optical properties of the imaged sample. Such an important aspect has already been described using theoretical models due to the difficulties of implementing a direct wavefront sensing scheme. However, these only stand for simple interfaces and c...

We present the performance of a compact, non expensive, easy to use ultrafast semiconductor disk laser (1W average power, 1.5 ps, 500MHz) for multiphoton imaging. The laser's operating wavelengths of 970 nm makes it ideal for nonlinear excitation of GFP as it has a two-photon action cross section peak at this wavelength. This property relaxes the r...

We demonstrate that sample induced aberrations can be measured in a nonlinear microscope. This uses the fact that two-photon excited fluorescence naturally produces a localized point source inside the sample: the nonlinear guide-star (NL-GS). The wavefront emitted from the NL-GS can then be recorded using a Shack-Hartmann sensor. Compensation of th...

Long term in vivo observations at large penetration depths and minimum sample disturbance are some of the key factors that have enabled the study of different cellular and tissue mechanisms. The continuous optimization of these aspects is the main driving force for the development of advanced microscopy techniques such as those based on nonlinear e...

The recent linkage between adaptive optics, a technique borrowed from astronomy and various imaging devices, has enabled to push forward their imaging capabilities by improving its contrast and resolution. A specific case is nonlinear microscopy (NLM) that, although it brings several inherent advantages (compared to linear fluorescence techniques)...

The use of the nonlinear guide-star concept is proposed. This principle is used to directly measure sample aberrations employing a wave front sensor and correcting them in a single step by shaping a deformable mirror.

We present a portable ultrafast Semiconductor Disk Laser (SDL) (or vertical extended cavity surface emitting laser—VECSELs), to be used for nonlinear microscopy. The SDL is modelocked using a quantum-dot semiconductor saturable absorber mirror (SESAM), delivering an average output power of 287 mW, with 1.5 ps pulses at 500 MHz and a central wavelen...

Ultrashort pulsed laser systems (such as Ti:sapphire) have been used in nonlinear microscopy during the last years. However, its implementation is not straight forward as they are maintenance-intensive, bulky and expensive. These limitations have prevented their wide-spread use for nonlinear imaging, especially in "real-life" biomedical application...

Implementation of AO in high performance microscopes is very dependent on the type of microscopy and the nature of the studied specimen. In this communication, we present the comparison between different implementations of AO sectioning microscopes. The analysis of the benefits and drawbacks of the correction strategies is also presented. Finally,...

In-vivo microscopic long term time-lapse studies require controlled imaging conditions to preserve sample viability. Therefore it is crucial to meet specific exposure conditions as these may limit the applicability of established techniques. In this work we demonstrate the use of third harmonic generation (THG) microscopy for long term time-lapse t...

To fully exploit the potential of nonlinear (NL) microscopy and enable its integration in clinical studies, inexpensive, simple, compact, efficient and sample-compatible ultrafast laser systems must be designed. Based on this, sample damage and NL signal enhancement criteria [1]; we propose the use of a compact (140x240x70 mm) semiconductor disk la...

Live microscopy techniques (i.e., differential interference contrast, confocal microscopy, etc.) have enabled the understanding of the mechanisms involved in cells and tissue formation. In long-term studies, special care must be taken in order to avoid sample damage, restricting the applicability of the different microscopy techniques. We demonstra...

C. elegans embryogenesis, at the cell division stage, was imaged using third harmonic generation microscopy employing ultrashort pulsed lasers at 1028nm and 1550nm. This technique could be used for cell tracking studies without fluorescent markers.

Nonlinear microscopy (NLM) has covered the requirement for higher contrast and resolution compared with other microscopy techniques, however, the optical quality of this imaging apparatus and the sample structure can compromise its capabilities. Here, we show that the imaging capabilities of a NLM can be affected by the aberrations produced by the...

Third-harmonic generation (THG) microscopy is attractive for long-term imaging on living organisms because it provides high resolution and requires no staining. Use of a femtosecond pulsed fibre laser at 1550 nm yields a signal in the visible range that is compatible with standard optics, and efficiently detectable with conventional photomultiplier...

1. ABSTRACT We investigate the optical quality of a custom made non-linear microscope and the associated sample aberrations through a systematic analysis based on wavefront sensing. Measurements are performed at each segment of the optical setup: before, inside, and after the non-linear microscope. Importantly, aberrations are also measured for the...