Alfred E. Mann, entrepreneur and philanthropist. (MannKind Corp. via AP)

Alfred E. Mann, a pioneering investor and philanthropist whose companies have developed breakthrough medical devices, including the first rechargeable pacemaker and an artificial retina that allows the blind to see, died Feb. 25 in Las Vegas. He was 90.

Matthew Pfeffer, chief executive of MannKind, confirmed the death. The cause was not immediately disclosed.

A prolific entrepreneur, Mr. Mann over the course of seven decades founded more than a dozen companies in fields including aerospace, pharmaceuticals and medical devices. He sold many of those companies over the years, amassing a fortune that topped $2.2 billion in 2007.

Over the past few weeks, Mr. Mann resigned from the boards of two of his companies: MannKind, a Valencia, Calif., firm that developed an inhalable form of insulin; and Second Sight Medical Products, a Sylmar, Calif., company that makes an electronic retina that gives rudimentary sight to patients blinded by certain eye diseases.

Those resignations came little more than a year after he stepped down as MannKind’s chief executive after a 12-year run.

In addition to his business interests, Mr. Mann was a polymath who designed his 17,000-square-foot mansion in Beverly Hills atop Mulholland Drive. The home featured a koi pond that stretched from the back yard into the home, separated by a Plexiglas wall that automatically rose up and down depending on the weather.

Mr. Mann was born Nov. 6, 1925, in Portland, Ore. His father was a grocer; his mother was a singer and pianist. Two of his siblings became musicians: violinist Robert Mann, a founder of the Juilliard String Quartet, and pianist Rosalind Koff.

Mr. Mann served in the Army Air Forces during World War II, then settled in California, earning a physics degree from the University of California at Los Angeles.

In the 1950s, he worked on military projects to improve guidance systems for missiles. He later won a contract to design solar cells for spacecraft. Those opportunities led him to found his first two companies, Spectrolab and Heliotek, both of which he sold in 1960.

In 1969, he turned his attention to medical devices, particularly to developing a more durable pacemaker with rechargeable batteries. The company Mr. Mann founded for that purpose, Pacesetter Systems, was sold to Siemens for $150 million in 1985.

Mr. Mann’s biggest deal came in 2001, when he sold MiniMed, a company that developed insulin pumps to treat diabetes, to medical device giant Medtronic for $3.3 billion.

Mr. Mann’s first three marriages ended in divorce. Survivors include his wife of 10 years, Claude Mann; seven children; his brother and sister; and 10 grandchildren.

One of Mr. Mann’s most recent ventures, MannKind, has been one of his least successful. The company’s only product, an inhalable insulin called Afrezza, was once seen as a potential blockbuster drug, but sales have been disappointing.

For years, Mr. Mann said he intended to leave most of his wealth to charities, including his foundation and engineering institutes he created at several universities, including the University of Southern California. His stakes in MannKind and Second Sight are valued at $233 million.

In a 1998 profile in the Los Angeles Times after Mr. Mann donated $100 million to USC, colleagues praised him for his wide-ranging contributions.

“He’s literally working on making the blind see, the deaf hear and the lame walk,” said Jeff Greiner, then president of Advanced Bionics, a Sylmar firm founded by Mr. Mann that makes cochlear implants. “That’s a pretty fantastic legacy if it comes to pass.”