New model helps to develop foods with customizable digestive qualities

Digestion is the process that allows the body breaks down a cheeseburger into nutrients that the cells in your body can use. With the help of new technology at UC Davis, this process can now be examined outside of the body.

Gail Bornhorst, an assistant professor of food science and technology, was on the team that first built the human gastric simulator (HGS), a model that simulates human digestion.

“Our main goal was to be able to simulate both the the physical and the chemical aspects of food digestion in order to understand food breakdown processes to be able to model those processes, ultimately [designing] better food products that have the functional properties that we want,” Bornhorst said.

The HGS is unique because it models both chemical and physical digestion, two independently complicated processes.

“The physical aspect is that [the HGS] essentially has these rollers that move down a stomach reactor, and those mimic the contractions of your stomach,” Bornhorst said. “Your stomach has muscular contractions and that’s how it breaks down the food particles.”

While chewing starts the process of physical digestion, it still leaves food particles largely intact, so as the rollers are moving along the stomach reactor, the process of chemical digestion is also happening.

Yamile Mennah-Govela, a Ph.D. student of food science and technology, also works in Bornhorst’s lab. Components for chemical digestion are made in the lab using a unique blend of enzymes, salts and glycoproteins that simulate saliva, gastric juice and internal fluids, according to Mennah-Govela.

“We make it as solution, and we make a bottle of it,” Mennah-Govela said. “We store it in the refrigerator and we can use it within one week for different trials.”

Although the process of modelling digestion may sound simple, the enzymes that your body produces, as well as other factors, can vary drastically.

“We do sequential digestion, where we would mimic the stomach and then mimic the small intestines,” Bornhorst said. “The challenging part about that is that there are a lot of control systems: how fast [food] empties from your stomach, the secretion of acids and enzymes, and a lot of those are dependent on the food product and they’re also dependent on the individual […] There’s some data that exists from human studies, but if you’re using a different food product, then the values may be very different.”

If digestion is so hard to recreate, it might seem counterintuitive to try to mimic the process outside of the human body. Karen Rios-Villa, a graduate student in the Food Science Department, also works in Bornhorst’s lab. According to Rios-Villa, there are a couple of reasons why the development of the HGS was necessary.

“Most of the research regarding nutrient release is related to the after-absorption process, but the transformation that the food suffers during digestion is still not clear,” Rios-Villa said in an e-mail interview. “A possible way to understand this process would be using animals (“in vivo”), but there are numerous ethical, economical and methodological limitations. Therefore, the development of tools that can help us in the simulation of digestion have been built in Prof. Gail Bornhorst Food Engineering Lab.”

One of the ways the HGS is being used is to study how different ways of preparing food can change the breakdown of proteins and overall bioavailability, or the percentage of each nutrient that your body is able to absorb, of the nutrients that food contains.

For example, Bornhorst’s group did some work with sweet potatoes, preparing them in various ways, feeding them through the machine and then analyzing the broken down food. In the future, Bornhorst sees a place for models like the HGS in trying to engineer foods with specific desired properties, like a food that will make people feel fuller, or have a slower or faster release of glucose.

“All those things are related to the properties of food products and what actually happens to them when you eat the food,” Bornhorst said. “Because the models that we’ve had in the past did not incorporate both the physical aspects and the chemical aspects, we were trying to optimize a system where we didn’t really understand what was going on. By creating these types of models, like our mechanical stomach model, what we’re really trying to do is to be able to understand, at a much more detailed level, what’s happening both to the structure as well as to the properties after you consume the food”.

Written by: Meral Basit — science@theaggie.org

New ultrasonic technology to change personal information security

Smartphones, tablets and laptops have become so personalized that just the touch of a finger can unlock a device. Although this idea may seem foolproof to identity theft and fraud, new ultrasonic technology developed at UC Berkeley and UC Davis was created as a more secure way to protect personal information than modern finger recognition.

“Today [smartphone technology has] flaws. [It is] not extremely secure,” said Bernhard Boser, a professor in the UC Berkeley Department of Electrical Engineering and Computer Sciences.

While modern technology allows access to a device granted by an individual’s unique fingerprint, the 2D image of a print can be copied and used as a fake print that can fool a sensor.

An ultrasonic sensor developed to capture images inside of human tissue is responsible for the new fingerprint recognition sensor that has the potential to be installed in all types of mobile devices.

“We have two different technologies: one is the ultrasonic sensor in air, and the other is the ultrasonic sensor in tissue,” said David Horsley of the UC Davis Department of Mechanical and Aerospace Engineering and collaborator of the ultrasonic technology project.

The compact ultrasonic technology captures a fingerprint in 3D to uniquely identify a person, imaging both the ridges and valleys of a fingerprint surface as well as the tissue right beneath the skin.

“We have made a new system using ultrasound technology, and it is much better. This imaging process can look at the surface of fingerprints and inside the finger,” Boser said. “There are more patterns inside the finger that can’t be put onto glass screen of a phone.”

The ultrasonic technology can sense the subsurface structure of the skin, distinguishing between layers of tissue by analyzing the densities of live and dead skin cells.

The additional third dimension of the fingerprint image will make it more difficult for someone trying to steal a fingerprint to unlock a phone or to commit identity theft.

On human hands, natural oils and sweat create the thin, barely noticeable fingerprints left behind on surfaces we touch. It is relatively easy for those fingerprints to be collected. A fake fingerprint can be made by taking a picture of a left-behind print on a phone screen and then copying it using a Xerox machine or 3D printer.

“The smartphone essentially contains all the info it needs to unlock it. This is quite a big security hole,” Boser said.

Individual electronic devices are so convenient that information stored on them might not only be personal, but include medical and financial information through apps like Wallet and Health on the iPhone.

“Imagine features such as Apple Pay and others that depend on fingerprint recognition. You don’t want people stealing your personal or financial information, because it is possible,” Horsley said. “This is something to be concerned about, so having a better system that is more secure is necessary.”

The hackable 2D fingerprint recognition scanner can be replaced with the ultrasonic 3D fingerprint touch sensor in all devices that utilize fingerprints as a way to secure information.

The research behind the ultrasonic technology started in 2007 with a collaboration between UC Berkeley and UC Davis, with the development of piezoelectric-micromachined ultrasonic transducers (PMUTs).

These transducers, devices that convert one type of energy to another, were the basis of the 3D fingerprint sensor technology.

The ultrasonic technology used in fingerprint recognition was inspired by the ultrasonic scanners commonly used in medical settings, such as viewing images of a fetus via a sonogram. However, the fingerprint scanner technology is much more compact and able to be installed in portable electronic devices like phones, laptops and tablets.

“The fingerprint sensor works kind of like the medical sensor. […] We made a pulse that emits ultrasound, and the transducers receive returning information about the composition of patterns on and just beneath the surface of the skin,” Horsley said.

Although many devoted Apple customers were excited about the release of an iPhone with a fingerprint recognition unlock feature, there were customers who were hesitant about how secure it really was.

“When the iPhone first came out with a fingerprint recognition unlock feature, the next day people proved that you could unlock the phone using a re-created fingerprint via Xerox or 3D printer,” Horsley said.

Despite the proof of how unsecure a 2D fingerprint recognition system may be, Apple, Android and other major-brand products have continued to flourish among consumers.

Installing a 3D ultrasonic fingerprint sensor, rather than the current 2D print recognition in mobile devices, offers a new design to smartphones.

“By putting the fingerprint sensor beneath glass of the screen, that smartphone could be redesigned, essentially eliminating the home-button feature,” Horsley said. “This is definitely a possibility for the iPhone 8.”

A commercial smartphone already exists with a fingerprint sensor under the glass screen: the Xiaomi Mi 5s. Xiaomi is a Chinese electronics manufacturer and the company is not planning to release these phones in the United States.

Another company involved in ultrasonic fingerprint sensors is Invensense, headquartered in San Jose, which announced in 2015 that they are manufacturing a sensor for mobile devices to be released in 2017.

The fingerprint touch sensor product is called the UltraPrint Mass, and it is able to be placed within a device without cutting a hole in display glass.

With the new development of ultrasonic technology for fingerprint sensors comes a new generation of electronic devices.

“There are two advantages [to our product]: one is the sensing over glass or metal, not plastic. Second, the technology can sense the live finger instead of the sensing just the fingerprint,” said Zaryab Hamavand, director of sales at Invensense. “Basically, the extra security is [that] it makes sure it is a live person’s finger, and not a copy of a print.”

Written by: Shivani Kamal — science@theaggie.org

Woodland tech startup works on developing world’s most sensitive pressure sensor

TacSense, Inc., a Woodland technology startup, is currently in the works of perfecting its latest and most advanced product yet — the world’s most sensitive and flexible pressure sensor. With the help of UC Davis alumni and engineering students, the company aims to develop medical devices that will benefit future biomedical advancements.

The company was founded in 2013 by Tingrui Pan, a UC Davis biomedical engineering professor. TacSense operates under two divisions: microfluidics, which is the science of controlling liquids on the micro and nanoliter scale, and sensors. Many of the company’s ideas and products were brainstormed in Pan’s UC Davis Micro-Nano Innovations (MiNI) Laboratory, including the plans for the world’s most sensitive pressure sensor.

“We’re trying to take some of the really brilliant ideas we came up with in [Pan’s] lab and turn them into commercial products,” said Aaron Cohen, TacSense’s chief technology officer and a UC Davis alumnus.

Pressure sensors are typically found in car passenger seats and control when to set off the airbags of a vehicle. They are also commonly used in the medical industry for compression therapy that helps increase blood circulation in legs.

The product developed in Pan’s MiNI Lab, called a super capacitive pressure sensor, is 1,000 times more sensitive than typical pressure sensors.

“This is a really revolutionary product,” Cohen said. “There aren’t any products like it on the market.”

TacSense employees are continuing to perfect the super-capacitive pressure sensor so that it may soon be available for future public use.

The microfluidics division has also been working on developing an advanced technology to help glaucoma patients.

Glaucoma is caused by a buildup of pressure in the eye that leads to blindness and is currently the leading cause of irreversible blindness in the world. The Brown Glaucoma Implant is the microfluidic device intended to ease pressure buildup by draining and expelling any excess pressure from the eye.

“What makes this implant special is that we use advanced technology to prevent the eye from being clogged by excess proteins and to allow the implant to be accepted by the body,” said Ben Bazor, TacSense’s Microfluidics division manager and a UC Davis alumnus.

According to Cohen, the device takes only a minute to install and is expected to prevent the development of glaucoma.

Since opening its doors in the summer of 2015, TacSense has hired multiple UC Davis alumni and students passionate about developing technology for biomedical advancements.

Bazor attributes his success at the company to his experience as a UC Davis undergraduate engineering student.

“I feel that taking engineering classes at UC Davis really helped me understand the framework of understanding things quickly in order to keep our projects on a timeline,” Bazor said. “It’s been a lot of work, but it’s also been a lot of fun.”

Undergraduate students have also found ways to get involved with the company and pursue their interests in biomedical engineering.

“My experience at TacSense has made me a lot more interested in pursuing biomedical technology and creating devices,” said Amber Chou, a third-year bioengineering major and the production technician at TacSense. “As a biomedical engineer, I can help people do things directly [with the new technology], and that’s really important to me.”

TacSense hopes to expand its company into China and other eastern markets in the future, while also diversifying their products to include fabric pressure sensors embedded in clothing.

Written by: Emma Sadlowski — science@theaggie.org